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WOODS
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A Guide for Producing the Best Lumber
By Gene Wengert
Presented by Wood-Mizer
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PART 1 Sawing the Best Lumber
LOG QUALITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
SAWMILLING QUALITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
HARDWOOD SAWING TECHNIQUES
Hardwood Lumber Grades and Prices . . . . . . . . . . . . . . . . . . . 7-8
Hardwood Sawing Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Opening Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Specific Sawing Suggestions
General Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Log Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Opening Face Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Sweepy Logs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Quartersawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
SOFTWOOD SAWING TECHNIQUE
Sawing Softwood Logs Into Construction Lumber . . . . . . . . . . 14
Sawing Softwood Logs into Boards and Lumber for
Remanufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
PART 2 Drying the Best Lumber
WHY DRY LUMBER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
MEASURING MOISTURE CONTENT . . . . . . . . . . . . . . . . . . . . 17
WATER IN THE WOOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
AS SOON AS THE LUMBER IS SAWN...
Drying Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Stacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
LUMBER DRYING
Initial Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Air-Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Kiln-Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
WOODS
WOODSHOP
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A Guide for Producing the Best Lumber
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TABLEOFCONTENTS
Wood is a valuable material. Although wood is plentiful in the U.S., with annual
growth of hardwoods exceeding harvest by 25% for the past 75 years, we need to
assure that we will not waste this valuable natural resource as we convert it into lum-
ber, and as we convert the lumber into furniture, cabinets, buildings, and other useful
products.
A nice size tree has just been felled in the woods. Your plans are to saw as much
of the tree as possible into high quality lumber. You want to do this with a minimal
amount of waste and, at the same time, you want to maximize the value and useful-
ness of the lumber you produce. How do you proceed?
This text was written to provide both the hobbyist and the professional with basic,
practical information on how to saw and dry lumber efficiently with minimal loss and
downfall. The best operating procedures begin in the woods just after the tree is
felled. In Part 1 of this booklet, practical, efficient sawmilling procedures that are dis-
cussed and illustrated. Suggested drying procedures are then presented. As a con-
clusion to this text, the final section lists sources of additional information on sawing
and drying.
All the information presented is based on decades of experience. Therefore, unless
there is a good reason not to follow the suggestions presented here, these guidelines
will be the most profitable and will waste as little of our resource as possible.
We hope that you find all the information you need to convert our valuable, renewable
resource into useful and durable wood products that will last for centuries.
HOW DRY IS DRY ENOUGH?
Achieving Proper Final Moisture Content . . . . . . . . . . . . . . . . . 20
ADDITIONAL QUALITY CHARACTERISTICS
OF THE DRYING PROCESS
Freedom from Checks and Splits . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Freedom from Warp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Freedom from Casehardening (Drying Stresses) . . . . . . . . . . . . . 21
Good Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
High Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Good Machinability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Good Gluability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
MEASURING MC
Oven-drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Electric Meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
PART 3 Additional Resources
SAWING AND GRADING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
DRYING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Gene Wengert
is Professor and
Extension Specialist
Emeritus, Department
of Forest Ecology and
Management, University
of Wisconsin-Madison,
and President of The
Wood Doctor’s Rx, LLC.
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SAWINGTHEBESTLUMBER
1
Log value is based on the amount and value of lum-
ber that will be produced. Based on the results from
sawing thousands of hardwood logs, the volume of
lumber produced, total and by grade, and the value
of the lumber produced from any size and grade log
can be estimated. Several examples for red oak logs
are given below (Table 1).
Logs that are crooked or short will produce much
less high-value lumber than long, straight logs.
Further, logs eight feet and shorter will seldom pro-
duce much high-quality lumber. Therefore, when
bucking a tree into logs, always try to maximize log
length, but at the same time, minimize crookedness.
These log length bucking decisions are critical for
large diameter logs. On the other hand, logs under
16 inches in diameter (small end, inside bark) will
seldom produce much high-quality lumber, so length
decisions for these smaller logs are not very critical.
Incidentally, it is typical that the length of logs is usu-
ally about 2 inches over the last full foot; that is, an
8-foot log is really 8' 2", an 11-foot log is 11' 2", and
so on.
Once the logs have been manufactured, they need to
be handled correctly and sawn promptly. Appreciate
that the way the logs are handled influences lumber
PART 1 Sawing the Best Lumber
Table 1 Lumber volume and value from various sized red oak logs
Log Log Log Lumber
Diameter Length Grade Selects & Btr No.1C No.2C No.3C Value
(inch) (feet) (Bd Ft) (Bd Ft) (Bd Ft) (Bd Ft) ($)
12 10 3 2 11 20 25 32
12 12 2 12 20 23 17 51
14 10 3 4 18 27 30 47
14 12 2 20 33 28 20 76
15 12 2 25 40 31 20 90
16 16 1 90 45 34 13 173
16 16 2 40 64 44 29 140
16 16 3 12 44 53 56 103
20 12 1 124 54 31 18 223
24 12 1 197 81 33 22 338
L U M B E R P R O D U C E D
quality. Logs stored for more than several weeks
in warm weather may have already begun to stain,
especially at the log ends and wherever the bark
has scuffed off. Therefore, prompt sawing of logs in
warm weather is essential.
Exposed log ends also are likely to begin drying
immediately, resulting in development of stain, end
cracks, splits, and checks. It is quite easy for the
stain and cracks to penetrate over six inches in just a
few months. Further, the dry ends are difficult to saw
accurately. The saw wanders excessively in this dry
wood, giving erratic lumber thicknesses. Therefore,
all logs should be end-coated promptly with a vapor
resistant coating (commercial wax coatings, such as
Anchor Seal, are very popular) to prevent end checks
and reduce the risk of end stain.
In addition to the damage that can be seen, such as
end stain and end cracks, stored logs have certain
undesirable chemical changes occurring within the
wood. Lumber from logs stored several months dur-
ing warm weather is at least 10 times more likely
to develop cracks and checks in drying. Lumber
from stored logs is perhaps 20 times more likely to
develop objectionable drying stains, including sticker
stain.
LOG QUALITY
It is difficult to produce high-quality lumber from logs that are knotty and crooked. Effective sawing decisions
require knowledge of the logs’ quality. So, the first step before sawmilling begins is always to evaluate or grade
the logs to estimate their quality. Logs are graded based on their faces. A log has four faces, each face repre-
senting 1/4 of the circumference and being the full length of the log (Figure 1). The four faces do not overlap
each other. A clear face is free of knots, knot scars on the bark, seams, splits, rot, insect damage, and so on.
The clearer the face, the higher the value and the better the lumber that will be produced from the log. Detailed
instructions for log grading are available from many state forestry offices, or request Forest Facts #74 (send
$2 and a SASE) to the Forestry Department of the University of Wisconsin, 1630 Linden Drive, Madison,
WI 53706.
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SAWMILLING QUALITY
Sawing procedures will influence lumber quality.
The following criteria are the technical basis used to
develop the suggested sawing procedures discussed
in the next section:
• The clearest, knot-free, strongest, most valuable
lumber is on the outside of a log. Quality goes
down as the lumber is sawn closer to the center
(called the pith) of the log.
• Wide, long, clear pieces of lumber are the most
valuable. The best hardwood lumber grade
guarantees that the lumber is at least 83% clear.
Attending a three-day hardwood lumber grad-
ing class is well worth the time and expense.
Contact the National Hardwood Lumber
Association for the dates of a class in your area:
(901) 377-1818. Hardwood lumber graders do
not need to be certified or licensed.
• Softwood lumber grading is much more complex
than hardwood lumber grading, and due to
safety concerns, must be done by a certified,
licensed grader. Most wood framed buildings
are required by the building codes to be built
with graded, certified lumber. Check with local
building officials for specific requirements and
rules in your area.
• Quartersawn lumber (with the rings going from
face to face, rather than edge to edge) requires
up to 30% longer drying time. Quartersawn
lumber has a different grain pattern than flat-
sawn, especially in oak, ash, sycamore, beech,
and hackberry. This grain may be unwanted
by some customers. When sawing quarter-
sawn lumber, yields of lumber from the log are
reduced, compared to more typical sawing pat-
terns. Quartersawn lumber may also shrink up
Face 2
Face 4
Face 3
Face 1
Knot
SeamFIGURE 1
to 1/16-inch more (per inch of thickness) than
flatsawn lumber during drying, meaning that the
green size may have to be increased, further
reducing yield.
• Thick lumber requires substantially longer drying
time and milder drying conditions. For example:
8/4 requires 2.5 times longer for drying than 4/4
lumber. Therefore, in most cases, saw lumber no
thicker than required. Do not saw thick lumber
that will be resawn into thinner pieces after dry-
ing. If thicker pieces are required, consider saw-
ing thinner pieces to glue together later. After
sawing, keep them in order, so that after drying
you can glue them back together in the same
order that they came from the log. In this way,
the grain of the small pieces matches very well;
it will be difficult to see that the large, thick piece
is actually made of several glued-up pieces of
wood!
• Lumber that has the rings off center (when look-
ing at the end grain of the lumber) will bend to
the side more often than not. Therefore, always
try to keep the rings centered so that the two
edges of the lumber are mirror images.
• Lumber including the pith will warp badly at
times and will almost always develop a large
split.
• Lumber from crooked logs has high slope of
grain (SOG). High SOG also results when the
lumber is not sawn parallel to the bark. Lumber
with such grain pattern will often warp badly
during drying. Lumber with a high SOG has
greatly reduced strength as well. Often, the
strength is critical when sawing softwood con-
struction lumber, so SOG is an important factor
to consider when evaluating and sawing logs.
Lumber with high SOG also machines poorly,
with grain tear-out and raised grain common.
• Softwood lumber intended for construction
purposes, with large knots near the edge is not
as strong as if the knots were in the center face.
Knots on the edges running toward the center of
the piece, called spike knots, make the piece of
lumber especially weak. Lumber with large knots
is weaker than lumber with smaller knots.
• Lumber intended for remanufacturing, especially
lumber that will be cut up into smaller pieces for
furniture, cabinets, and so on, is most valuable if
the knots are near an edge or end, maximizing
the size (length and width) of the clear, knot-free
areas in the lumber.
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SAWINGTHEBESTLUMBER
1
Hardwood Lumber Grades and Prices
There are five basic grades of hardwood lumber
(Figure 2)—FAS, Selects (sometimes sold as FAS
1-Face), No.1 Common, No.2 Common, and No.3
Common. Here is a brief summary of the grades:
FAS is a piece of lumber that is at least 83% clear
on the worst side of the piece. (Clear means free
from rot, pith, shake, wane, knots, stain, and other
defects.) The clear area or areas are wide and long;
the lumber itself must be at least 6” x 8’.
No.1 Common is at least 67% clear on the worst
side of the lumber. The clear areas can be smaller
HARDWOOD SAWING TECHNIQUES
The initial sawing operation is THE KEY to obtaining the highest dollar return and the most useful lumber
from every log processed. The operator of the saw, the “sawyer,” must recognize the potential product grade
mix that will maximize the value of the log, and then manipulate the log to achieve this maximum value. This
requires a “sixth sense” with x-ray vision to visualize what is inside the log before it is sawn.
In order to do an effective job, the sawyer must receive logs that have been properly felled and handled. Logs
should not have large protuberances, pronounced crook, kink, or sweep, or jagged ends. Log ends should
not be dried out. In short, the sawyer is no magician—the way that logs are harvested, bucked to length, and
stored before sawing affects their potential value when sawn into lumber.
To optimize log and product value, the sawyer must also consider how the lumber will be edged and trimmed.
If the edging and trimming are not done by the sawyer, then the edgerman, trimmerman and sawyer must
develop good communication along with a high degree of skill and judgment. They must act together as a
team. They also must operate their equipment safely and efficiently. As a minimum, these people must have a
thorough understanding of lumber grades and current lumber values.
FIGURE 2
FAS
$9.50
No.1C
$6.50
No. 2AC
$3.00
No. 3AC
$2.25
No. 3BC
$1.75
wane
knots
split
worm holes
stain
than with FAS. Common lumber can be as short as
4’ and as narrow as 3”.
Selects and FAS 1-Face are No.1 Common pieces
that have the better face equivalent to FAS.
No.2 Common is 50% clear on the worst side and
stain is a defect, but with No.2B Common, stain is
not a defect and is ignored.
No.3A Common is 33% clear on the worst side. The
lowest grade, No.3B Common, requires only 25% of
the piece to be sound, not clear.
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There are many special cases and situa-
tions when grading lumber; this is just a
general summary. The NHLA publishes an
illustrated Inspection School Manual (refer-
enced in Part 3 of this report) to help learn
the grading rules.
Lumber prices on the retail market vary tre-
mendously, even within an individual state.
Upper grades of kiln-dried No.1 Common
and Better will sell quickly and at very prof-
itable prices. The wholesale market prices
for lumber vary month to month. Several
publications tabulate and publish current
prices, including the Hardwood Market
Report (Memphis, TN) and the Weekly
Hardwood Review (Charlotte, NC). Some
typical 2005 prices for kiln-dried lumber
(wholesale, FOB mill, gross tally) are given
in Table 2. State forestry officials may also
publish a newsletter that has ads for lum-
ber.
Usually, the green lumber or air-dried lumber prices
are lower by $250 or more per MBF. Note that the
prices quoted are based on measurement of footage
and grade after drying.
For most species, there are poor markets and poor
profits for lower grades of lumber, No.2 Common and
Table 2 Typical Prices of Kiln-Dried,
4/4 Hardwood Lumber (12/05)
Species FAS No. 1C No. 2C
- - - - - - $ / MBF - - - - - -
Ash 1110 780 570
Birch, yellow 1800 1215 805
Cherry 3000 1745 1000
Cottonwood 755 500 250
Maple, hard 2510 1820 1110
Maple, soft 1725 1000 550
Oak, red 1525 875 645
Oak, white 1550 820 570
Walnut 2520 1405 1165
Yellow poplar 885 560 400
Below, especially if sold green. Yet, some lower-grade
logs may produce 50% of this low-grade lumber.
The most profitable option for lower-grade lumber is
to kiln-dry the lumber and then cut the lumber into
smaller, clear (or nearly clear) pieces before selling.
Although small pieces cannot be graded with stan-
dard rules, such pieces are very attractive for hobbyist
and small businesses. Typically, these pieces would
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SAWINGTHEBESTLUMBER
1
3 - Cant Sawing
The log is sawn much like grade sawing, but the
center of the log, which may be a piece with
dimensions of 7” x 9”, 10” x 10”, or so, is either sent
to another machine for further processing or is sold as
a large (and heavy) timber (Figure 5). Cant sawing
maximizes sawmill production (board feet per day)
and is commonly used throughout the hardwood
industry in medium and large size mills. It is used
primarily on medium- and low-quality logs where the
lumber from the center of the log will not be very
high in value. With cant sawing, valuable time and
effort is not wasted manufacturing low-grade,
low-value lumber.
Face 4
Face 2
Face 3
Face 1
FIGURE 3
Face 2 Face 3
FIGURE 4
Face 3
Face 3
Face 3
Face 3CANT
FIGURE 5
Hardwood Sawing Patterns
The actual sawing pattern used (sawing pattern includes lumber thickness, log rotation, and taper offset)
depends on many factors, including species, log quality, log size, mill design, sawing equipment, and lumber
grade values. There are three basic sawing options for standard lumber; however, for quartersawn lumber, see
Figure 5 and the accompanying discussion.
1 - Grade Sawing (or Around Sawing)
The log is sawn and turned to a new face, sawn and
turned again, perhaps turned as many as five times
(Figure 3). This is the best (financially) for medium-
and high-quality logs, even though it may be difficult
to turn a log on some mills and daily production vol-
ume may be lower. Hydraulic log turning is much bet-
ter than “arm-strong” power!
2 - Live Sawing
(or Through-and-Through Sawing)
The log is sawn about halfway through on the opening
face and then turned once to the opposite face and
sawn on that face until finished (Figure 4). Although
this can be the easiest and quickest sawing method,
live sawing means that every piece of lumber must be
edged—for highest value, many pieces will be ripped
into two or three pieces as well. Further, live-sawn
lumber is quite wide and heavy, is lower in grade, and
has a lot of quartersawn grain. Live-sawn lumber often
has excessive warp in the drying process. In short,
live-sawing is usually best only for lower quality logs
where the above disadvantages are not important.
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Opening Face
Of all the decisions facing the sawyer, the decision as to which face to open first (that is, where to begin
sawing) is the most important. (A log is divided into four faces, each face being of the log’s circumference, full
length, and not overlapping another face. Once the slab is removed from a face, the flat surface is the face.)
The choice of the opening face determines the location of all the other faces. Initially, a log could be sawn in
several million different ways; only a hundred of these ways are most profitable! Once the opening face is cho-
sen, there are now only several thousand decisions for the sawyer to make.
In grade or cant sawing methods, there are two basic opening face options—
Option #1: The poorest face of the four faces is opened first without any taper set. (Taper set refers to
the process of raising or skewing the log so that the saw cuts parallel to the bark on the face being sawn.)
Because this is the poorest face, this means that short lumber and potentially large slabs will come from the
very low-value part of the log. With no taper setting, it means that the opposite face, which is a better face, will
be sawn parallel to the bark when the log is turned without having to use taper sets on that face. As a result,
higher-grade lumber which comes from this better face will be full length.
Option #2: The best face on the log is opened first with full taper. Full taper means that the log is raised or
skewed as much as needed so that the first cut runs parallel to the bark. This means, as in Option #1, that the
higher grade face will be sawn parallel to the bark and will produce full-length lumber.
The end results of either method will be nearly the same, but there is one advantage to Option #2. It is
easier to position the log (i.e., rotate it slightly) so that the opening face is as clear (free of defects) as possible.
With Option #1, the back side (or opposite side) of the log is the better face, but fine-tuning the rotation is diffi-
cult as the back side cannot be seen easily in a production situation. When sawing a high-grade log with many
clear areas and faces, the difference between Option #1 and #2 is small. However, in a lower-grade log with
limited clearness, Option #2 will often prove to be better.
Face 2
Face 4
Face 3
Face 1
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SAWINGTHEBESTLUMBER
1General Recommendations
HIGH-QUALITY BUTT LOGS (a butt log is the
bottom log of the tree) will yield the most valuable
lumber. Therefore, when sawing such logs, the saw-
yer must determine which mix of thicknesses will
maximize the volume and value recovery for each
log face. As the price of lumber increases with thick-
ness—for example, 4/4, FAS, green hard maple
sells at $1060 per MBF wholesale, while 8/4 sells at
$1210—and because thicker lumber has less saw-
dust and higher lumber yields per log (as
much as 10% more lumber for a log sawn
into 8/4 versus 4/4), this decision can have
a large impact on profits. However, if, when
producing thicker lumber, the grade of the
lumber drops to No. 2 Common or lower,
even though the better side is clear or nearly
clear, there would be substantial loss, as
the market for thick, low-grade lumber is
poor. The sawyer must try to switch to 4/4
or 5/4 thickness before the grade drops.
(Remember—you do not make any money
sawing lumber until the lumber is sold. For
this reason, the grades, value, and useful-
ness of the lumber produced is critical for
profitable operations.)
From these high-quality logs, production of
large timber and railway ties from the center
would often be ill-advised, as these large cants will
often have substantial middle- and high-grade lum-
ber. In other words, cant value would be less than
lumber value.
For these high-grade logs, grade sawing is recom-
mended. In fact, taper-sawing (skewing the log on
the carriage so that lumber is sawn parallel to the
bark) is recommended for all “good” faces. This will
result in putting clear wood into full-length, more
valuable pieces of lumber and will avoid cutting clear
wood into short pieces. When the lower-grade por-
tion of the log is reached, then any taper would be
taken out of the log; that is, a wedge-shaped piece
would be cut to square the remaining cant and mini-
mize edging of the
remaining pieces.
MEDIUM-QUALITY LOGS offer considerable
challenge to the sawyer because they contain large
volumes of No. 1 Common and Better lumber. It
takes skill to recover this valuable lumber. Grade
sawing, which means rotating the log from one face
to the next, will provide the highest value; these rota-
tion decisions are critical decisions.
Specific Sawing Suggestions
(NOTE: All suggestion here must factor in safety requirements first!)
To begin, the sawyer (using Option #1) selects the
worst face and opens it without taper. Do not saw
the opening, low-grade face very long before rota-
tion. With a small log, the worst face could have just
a slab removed (that is, just one cut full-length), or
a slab and a short board before the log is rotated to
the opposite face. With a larger log, several short
pieces of lumber could be removed, and at times
even a full-length piece could be sawn.
Alternately, the sawyer (using Option #2) selects the
best face and opens it with full taper. This face is
then sawn heavily before the log is rotated to another
face.
POOR QUALITY, SOUND LOGS which will produce
no higher than No. 2 Common lumber should be
sawn as quickly as possible. In other words, there
is little or no profit in these logs, so they should be
removed from the sawmill as quickly as possible.
Any sawing method is acceptable, so long as the
log can be sawn quickly and safely. Most often the
log would be cant-sawn (often financially the best)
or live-sawn. Every minute of sawing time carries a
price ticket, so it is important to achieve the compro-
mise between sawing cost (perhaps $100 per MBF)
and lumber value. Log-turning should be kept to an
absolute minimum for low-value logs.
UNSOUND LOGS should never be purchased in the
first place as profit is nonexistent and safety risk can
be high. It is a better investment to spend money for
higher-quality logs which have good profit potential
than to purchase low-grade, unsound, non-profit
logs.
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Log Rotation
Lumber is sawn off of one face until the sawyer
expects that the next piece of lumber to be sawn
will be lower in grade than if lumber were sawn off of
the adjacent faces. (Exception: A “worst face” must
be sawn deep enough to achieve a satisfactory flat
surface before turning the log to another face.) When
the grade estimate for the present face is lower than
either of the adjacent faces, the log is rotated to a
new face. (In other words, a good face is sawn deep-
ly; a poor face may only be slabbed or have a slab
and one board removed.) This rule for rotation applies
to all faces and throughout the sawing process.
It is preferred that the log is rotated 180 degrees
from the opening face to the second face. As many
mills do not use this rotation pattern, even though it
has been standard since 1956, it is necessary to dis-
cuss the advantages in more detail.
Consider a 24-inch log (it works for any size log,
however). The 180-degree rotation results in 8 pieces
needing edging, while the poor method (always
rotating to an adjacent face) results in 13 pieces that
need to be edged. This alone is quite significant
in terms of work load for a small sawmiller. The
180- degree rotation method produces more wide
pieces, which are usually more valuable (Table
3). In addition, there are 8 pieces in the adjacent
method that have rings that are not centered,
edge to edge, which means that these pieces are
likely to develop side-bend in drying. Further, if
this is a species like walnut or red oak with a nar-
row band of sapwood, in the 180-degree method,
10 pieces will have sapwood in them; in the adja-
cent method, 13 pieces. Sapwood causes drying
problems (checks easier for oak) and also color
problems for some customers. The effect of log
stress or “spring” is minimized with 180 rotation,
as well.
We are aware that rotating to an adjacent face may
be easier, but the economic and safety benefits
strongly encourage 180-degree rotation. After the
first two opposite faces are sawn, the third and
fourth face are sawn. When beginning on the third
and fourth faces (which are opposite each other), the
poorer face of the two is opened first with no taper,
if this third face is not very high quality. However, a
high-quality face should probably always be opened
parallel to the bark, which means that taper-setting is
required.
Opening Face Sizes
The width of the opening face, or width of the slab-
bing cut, on all of the four faces is critical.
Good Grade Face
If the sawyer believes that the grade of the first piece
of lumber that will be sawn is high grade (Select, FAS
1-Face, or FAS), then the minimum width of the open-
ing face (that is, the minimum width of wood measured
on the log) should be 6-1/2 inches. This width is con-
sidered along the entire length of the log. (Why do we
use 6-1/2 inch opening size? Because FAS 1-Face and
FAS lumber must be at least 6 inches wide. To allow
for shrinkage and perhaps a little light edging at times,
plus because a little extra width can help the lumber
achieve the desired grade, 6-1/2-inch width is recom-
mended rather than 6.0 inches. Although Selects can
be 4- or 5-inches wide, the wane restrictions on these
pieces are so severe that they are not worth manufac-
turing intentionally.)
Lower Grade Face
If the sawyer believes that the best grade of lumber
that can be produced is No. 1 Common or lower, then
the minimum opening face width should be 4-1/2
inches. This opening width is only considered along
a 4-foot length of the log, assuming that the short-
est piece of lumber that can be sold is four feet long.
(Adjust this length for the shortest piece that is sold at
your mill.)
Sweepy Logs
Better quality logs with pronounced sweep should
be sawn initially with the “belly” to the saw or with
the “ears” to the saw, rather than by looking for clear
faces. The ears are typically removed in one or two
passes, providing a flat surface along the entire log
length. The belly can be sawn in several passes, often
producing some short, clear pieces of lumber. Once
the log is squared, then the remaining two faces are
sawn, most often turning the log only once, but using
standard log turning rules and procedures mentioned
previously. (Hint: When edging lumber from the belly,
long and narrow is better than fat and short.)
Poor-quality logs with pronounced sweep should never
reach the sawmill if the purpose of the lumber is for
profit.
Table 3 The size of pieces of lumber sawn with
180 degree rotation and with adjacent from a
24-inch diameter log.
Width of Lumber Number of Pieces
180 Degree Adjacent
20" 2 1
17" 2 1
15" 0 1
14" 2 3
13" 0 2
11" 10 8
10" 2 1
12

13
SAWINGTHEBESTLUMBER
1
Quartersawing
Quartersawn lumber offers several advantages compared to flatsawn lumber. Quartersawn lumber typically has
heavy ray fleck, which some people find appealing. Quartersawn has about half of the shrinkage in width as
flatsawn (3% instead of 6% when drying). Quartersawn lumber dries flatter and has less risk of checking dur-
ing drying. Quartersawn lumber is more stable in an environment with varying humidity. Quartersawn lumber
wears more evenly when used as flooring.
On the other hand, producing quartersawn lumber often results in 20% lower yields from the log. Lumber
production rates are much lower as well. Quartersawn lumber requires 15% or so longer drying times.
Quartersawn lumber shrinks twice as much in thickness as flatsawn. Quartersawn lumber will have spike
knots, compared to the circular knots in flatsawn lumber; spike knots greatly reduce the strength of lumber.
Sawing procedures are illustrated in Figure 6 for large logs and Figure 7 for smaller logs. As always, sawing
must be done with safety in mind.
6 1/2"
for a Good Log and Full Length
Opening Face
4 1/2"
for a Lower Quality Log
and 4' Long
4 '
Opening Face
FIGURE 6
FIGURE 7
13

14
Step 1. Position the log so that the smaller defects
will show up in the center of the lumber, where such
defects are less serious with respect to strength.
When possible, consider putting all the knots or
other defects into one face leaving the other faces
clear. However, for construction lumber, usually a
clear piece is no more valuable than a piece with a
few small knots. On the other hand, large knots or
defects will always be strength-reducing.
Step 2. Choose the worst face of the log and begin
sawing on this worst face, producing short pieces of
lumber. Do not taper saw (or offset) the log. Rather,
take any and all taper out of the log on this worst face.
The first piece will be low-grade and should be the
shortest piece that you can market. Long and narrow
is better than short and wide in most cases.
Step 3. After the worst side has a flat surface from end
to end (and maybe one or two pieces of lumber have
been cut if the log is quite large), then go to the
opposite face, sawing parallel to the bark, producing
a full-length piece of lumber. Turning to the opposite
face reduces the workload when edging the pieces,
meaning less warp in drying and wider pieces will be
produced, compared to going to an adjacent face for
the second face.
On a good face, the opening width should typically be
6 inches, which means that the first piece of lumber
will be 6 inches wide and full-length. On a smaller log
(under 13 inches in diameter), the production of 4-inch
width for the first piece is probably better.
A butt log will have less defect in the center and so
should probably not be converted into a large timber,
but should be sawn entirely into lumber.
Step 4. Always turn the log from the present face to
another face if the grade of lumber on the adjacent
faces would be higher than the piece produced on the
existing face.
Step 5. Sweepy logs. (Figure 8) Saw the ears off in
one cut, unless there is useable lumber in the ears.
Then rotate to the belly, perhaps producing some short
pieces of lumber. Sweepy, low-grade logs are a waste
of time.
SOFTWOOD SAWING TECHNIQUES
Many of the techniques used for hardwood log sawing apply to softwoods as well. A few differences are
highlighted in the following two sections.
Sweepy Log
FIGURE 8
Sawing Softwood Logs Into Construction Lumber
The following outline indicates the best way (most economical way) to saw softwood logs most of the time.
Certainly, safety concerns must override volume or value concerns.
Sawing Softwood Logs into Boards and Lumber for Remanufacturing
The log-sawing procedures are similar to the construction lumber sawing, except for the opening face size. On
a good face, the opening width should typically be 6-1/2 inches, which means that the first piece of lumber will
be 6-1/2 inches wide and full-length. On a smaller log (under 13 inches in diameter), the production of 4-1/2 inch
width for the first piece is probably better. The opening piece should probably be 4/4 thick, rather than 8/4, if there
is a market for 4/4. A butt log will have less defect in the center and so should probably not be converted into a
large timber, but should be sawn entirely into lumber.
14

15
SAWINGTHEBESTLUMBER
1
SUMMARY
• Converting logs into lumber can be quite profitable and
rewarding if done properly and safely.
• Log storage should be as short as possible.
• Logs should be end-coated.
• Logs should be opened on the worst face without
taper, or the best face with taper.
• Opening face widths should be 4-1/2 or 6-1/2 inches
for hardwoods, and 6 inches for softwoods, typically.
• Logs should be turned whenever an adjacent face
promises to have higher grade lumber.
1
15

17
DRYINGTHEBESTLUMBER
2
DRYINGTHEBESTLUMBER
2
WHY DRY LUMBER?
With only a few exceptions, dry lumber is more valuable than undried; kiln-dried is more valuable than
air-dried. The advantages of dry lumber include:
• Lumber under 22% moisture content (MC) has no risk of developing fungal stain, decay, rot, or mold.
• Dry lumber weighs over 50% less than wet lumber.
• Dry lumber is over twice as strong and twice as stiff as wet lumber.
• Nails and screws in dry lumber have higher holding power.
• Dry lumber is easier to glue.
• Dry lumber machines better than wet lumber (unless dried under 5% MC).
• Dry wood finishes easier.
• Dry lumber will shrink and swell in-use less than wet lumber that dries in-use.
PART 2 Drying the Best Lumber
You have just finished sawing a log into lumber. Several pieces of lumber look fairly clear with a very good
grain pattern—these pieces may be potentially quite valuable and useful after they are dried. What needs to
be done in order to avoid any quality loss before the lumber is sold green-from-the-saw? Or, what are the next
steps in order to produce high-quality kiln-dried lumber ready for manufacturing into cabinets, furniture,
millwork, or other items? The following sections review the best procedures for drying lumber.
MOISTURE CONTENT
The amount of water in lumber is measured as a
percentage of the lumber’s oven-dry weight. For
example, in a piece of lumber weighing 10 pounds,
if there are 4 pounds of water and 6 pounds of dry
wood, the moisture content is 67%. This value is
calculated as the weight of water divided by the
oven-dry weight, times 100 to convert to percentage.
So, in this example: 4 ÷ 6 x 100 = 67%.
WATER IN WOOD
The living tree contains a great deal of moisture—
this moisture is the “life blood” of the tree, conduct-
ing nutrients from the roots to the leaves, where the
process of photosynthesis takes place. The water
content, incidentally, remains the same year-round—
the sap is not up in the summer and down in the
winter.
In the living tree, wood typically has a moisture
content of 75% or higher. (One-thousand board
feet of oak can weigh 4900 pounds. At 75% MC,
there are 2100 pounds of water and 2800 pounds
of wood.) In order to use lumber for furniture, cabi-
nets, millwork, and similar indoor uses, almost all of
the water must be removed—the removal process
is called “drying.” For interior uses, the moisture
content should be 7%, which is equivalent to the
MC that wood will achieve in a relative humidity of
38% RH—the typical interior average RH for most
homes and offices. (This means, using the previous
example, that all but 196 pounds of water must be
removed before the oak can be used.)
17

18
Sorting
Once lumber is sawn, it is usually sorted into differ-
ent size and value groups in order to facilitate han-
dling and to obtain the highest quality.
Lumber is always sorted by species, although
sometimes red and white oak will be mixed together.
Lumber is always sorted by thicknesses, as well. It is
not advisable to mix thicknesses in the same pile or
stack of lumber. If thick and thin lumber is a problem,
then run the lumber through a single-headed
planer to achieve more uniform thickness.
Lumber is usually sorted by grade or quality clas-
sification; often only two sorts are used--valuable
lumber (intended for furniture, cabinets, etc.) and
the less valuable, industrial grade lumber. This grade
sorting is done so that the higher-valued lumber can
be treated more carefully than the low-quality lumber.
Further, lower-quality lumber is often sold green; it is
rarely kiln-dried.
Stacking
Once sorted, the green lumber is stacked for drying
in order to maintain the highest quality (Figure 9).
Lumber is stacked in layers, with all the lumber in
each layer being the same thickness. A layer is typi-
cally 4 to 6 feet wide. Narrow layers result in faster
drying, but also result in piles that can tip over more
easily. The length of the layer is the length of the
lumber, with the longer pieces being used on the
outside edges.
5 '
3/4"
1
1/2' to
2'
stickers
Each layer of lumber is separated from the one
above by wooden spacers called stickers. The stick-
ers, made of any DRY species of wood, are placed
perpendicular to the lumber’s length. The width of
the layer is the length of the sticker. The stickers are
spaced, starting at one end of the lumber, every 24
inches (although many operations use 12-, 16-, or
18-inch spacings in order to keep the lumber even
flatter). The stickers keep the lumber flat and provide
space for air flow in the drying process. The stick-
ers in one layer must be perfectly vertically aligned
(no greater than 1/2 inch variation) with the stickers
in layers below and above. A pile or stack is several
layers of stickered lumber.
It would be best if the lumber within one stack is all
the same length. However, if a few shorter pieces
are included (but never more than a 2-foot difference
between the shortest and longest), then place the
longer pieces on the outside edges of the layer and
keep the shorter ones on the inside. The ends of the
shorter pieces should always be supported with a
sticker; therefore, an extra sticker may have to be
used in some layers.
Once stacked, the lumber is placed in a good drying
location (even if it will be sold in a few days) where
the air can move through the package.
AS SOON AS THE LUMBER IS SAWN . . .
Drying Risks
There are three major risks for lumber that has been freshly sawn:
• The lumber is subject to attack from insects.
• The lumber is likely to stain, including mold and mildew stains.
• The lumber is likely to crack, if exposed to sun or dry air for a few hours before stacking.
To keep lumber valuable and to avoid wasting this precious natural resource, lumber must be handled
correctly from the moment it leaves the saw. If handled improperly at the mill, especially the white woods like
maple and pine, can develop stain within 24 hours during warm weather (although often the stain itself doesn’t
show up until later). All species can develop value-reducing end splits within several days. Oak and beech are
especially susceptible to surface cracks (or checks).
FIGURE 9
18

19
DRYINGTHEBESTLUMBER
2Initial Drying
The best results are obtained if the lumber is put into
a kiln or into controlled drying as quickly as possible.
The second best approach is using a shed (a pole
shed without walls is ideal) where the lumber is pro-
tected from direct rain and sun. Drying sheds require
good air flow, so a barn or closed shed is usually too
slow. On some species, adding fans to the shed will
help develop the lightest, brightest color. By shed-
drying before kiln-drying, the annual volume of lum-
ber dried in the kiln can be quadrupled, compared to
kiln-drying green-from-the-saw.
Air-Drying
Remember: Slow drying, such as from slow airflow
or high humidity, may result in stain. Fast drying,
such as from excessive airflow or low humidities,
can result in excessive cracking and splitting. The
air-drying process needs to be controlled as closely
as possible to avoid extreme conditions that may
result in quality loss.
The pile is usually stacked at least 12 inches above
the ground to avoid trapping moist air under the
pack. The pile should be covered on the top to
prevent direct exposure of the lumber to rain and
sunshine. More complete instructions on options
for quality air-drying are included in Air Drying of
Lumber, U.S. Department of Agriculture Handbook
No. 402. Although out of print, this handbook is
available in most large libraries and can be obtained
on inter-library loan from most smaller libraries.
Although air-drying is simple and easy, it is not
unusual to have in excess of 10% loss in quality
due to the variability and extremes of the weather.
Can you afford this? If not, consider shed-drying. (If
someone stole 10% of your lumber, wouldn’t you do
something about it?) As mentioned, in shed-drying,
lumber is placed in an open shed, thereby avoid-
ing direct sunlight and rainfall. Drying rates can be
regulated by using plastic mesh curtains--pull them
closed during hot, dry weather; open them during
cool or damp weather. Final moisture is typically over
20% MC.
With either air-drying or shed-drying, the lumber piles
need to be placed on a flat foundation with at least
8 inches of clear area underneath. If the air under-
neath the piles cannot flow out easily, high humidities
will develop under the piles leading to poor drying
and a risk of stain. If the foundation is crooked, then
warped lumber is likely.
Kiln-Drying
The process referred to as “kiln-drying” involves
putting the lumber in a chamber in which the tem-
perature, humidity, and air velocity through the lum-
ber are controlled. By controlling these three environ-
mental variables, the drying rate and the quality of
the lumber are controlled. Final moistures are as low
as 6% MC.
The smaller producer of kiln-dried lumber has several
major choices of equipment. As a broad generaliza-
tion, solar-heated dry kilns are best for producing
under 25,000 board feet (25 MBF) of lumber annually.
Under 2 million board feet (2 MMBF), most
operations will find that an electrically operated
dehumidification (DH) kiln is best.
Plans for building a solar kiln are available on the
Internet (www.woodweb.com). Solar kiln kits are
available from Wood-Mizer. Often, a solar kiln will
pay for itself after drying just three or four loads of
lumber.
Dehumidifier kilns are more expensive than solar,
but can provide top quality kiln-dried lumber year-
round, regardless of whether the sun is shining or
not. Economic aspects of a dehumidifier kiln are dis-
cussed in Opportunities for Dehumidification Drying
of Hardwood Lumber which is available from the
Virginia Forest Products Association (P.O. Box 160,
Sandston, VA 23150). The cost of operating a DH kiln
can be as high as $75 per MBF. However, the value
added by drying is often $300 per MBF. The return
on investment with a dehumidifier can be over 20%
after taxes.
Dryer operation is discussed in many texts. Three-
to five-day short courses are conducted annually
throughout the U.S. and Canada. Look for
advertisements in trade magazines or contact state
forest products specialists.
LUMBER DRYING
19

20
HOW DRY IS DRY ENOUGH?
Lumber should be dried to a final MC that is as close to the expected MC that the wood will achieve in use.
This guideline is established so as to avoid warping and size change problems in the final product. The MC
of wood in-use is related to the relative humidity (RH) that the wood is exposed to; temperature is irrelevant.
Different species have the same in-use MC if exposed to the same RH. A special term is used to relate RH to
MC in wood; the EMC (equilibrium moisture content) of air is numerically equal to the MC that wood will have
when exposed to a given RH. The following tabulation (Table 4) summarizes this relationship.
RULE: The basic rule for drying lumber is that the final MC in the kiln should be within 2% MC of the expected
EMC in-use to avoid moisture-related problems. Failure to observe this rule can easily result in manufacturing
losses exceeding $1000 per MBF, as well as loss of future sales and customers, and may even result in a law-
suit.
As a general rule of thumb, wood shrinks in width or thickness about 1% for every 4% MC change. (This is a
general rule, with some variation from species to species. Teak shrinks much less, 1% for 8% MC; oak shrinks
much more, 1% for 3% MC.) This means that if a 2-1/2-inch-wide piece of oak loses 3% MC, it will shrink
1% or 0.025 inches! This seems like a small amount of shrinkage, but when gluing, the maximum gap allowed
between two pieces of wood is only 0.006 inches. Further, if this oak piece is actually a piece of flooring in a
30-foot wide floor and the entire floor is losing 3% MC, the total shrinkage is 4 inches, which probably is dis-
tributed across the floor with objectionable cracks every foot or so.
Table 4 The relationship between humidity, EMC and wood use in North America.

RH MC EMC Condition
% % %
0 0 0 Oven-dry
30 6 6 Lower limit in most homes and offices
Lower limit for hardwood furniture and cabinet lumber
36 7 7 Average for hardwood furniture and cabinet lumber
44 8 8 Lower limit for softwood remanufacturing lumber
50 9 9 Upper limit in most homes and offices
Upper limit for softwood remanufacturing lumber
65 12 12 Average outside condition, winter and summer
Average for softwood construction lumber
80 16 16 Outside condition for coastal areas
Achieving Proper Final Moisture Content
Lumber needs to be properly stacked, with sticker openings being uniform in size. Narrow piles (6 feet or
under) have more uniform drying than wider piles. In dry kilns, uniformity of temperature, relative humidity, and
velocity is required. This uniformity is most critical when the lumber is above 40% MC and also when the lum-
ber is under 10% MC. In the kiln, uniform airflow and frequent airflow reversal (two hours) improve uniformity.
Equalization should be used for as long as required to achieve the desired uniformity of final MC—it may take
longer than 24 hours with some loads. The lumber should be as uniform in thickness and initial MC as possible.
Moisture samples need to be accurate and properly prepared. With as many as 5000 pieces of lumber in a
kiln, will just 8 or 10 samples give an adequate picture of the final MC? I suggest 30 samples be taken using a
hand-held moisture meter when the kiln is being unloaded to ascertain the correct final MC. When such sam-
pling is done, also look for areas in the kiln that are consistently wetter or drier than other areas. Make sure
that your moisture measuring technique can detect pieces under 6.0% MC—over-dried lumber is a serious
quality problem when machining or gluing.
20

21
DRYINGTHEBESTLUMBER
2
DRYINGTHEBESTLUMBER
2
Freedom from Checks and Splits
All lumber should be end-coated as soon as possible
after it is sawn. Good stacking and good control of
lumber lengths will help prevent the ends from drying
too quickly. High relative humidity at MCs above
40% are critical. Moderate air flows and lower tem-
peratures are also important. Above all, the drying
rate must be controlled to within narrow limits—the
precise rate depends on the species and thickness
of the lumber.
Freedom from Warp
Except for cupping, and warp caused by bad stack-
ing (such as non-uniform sticker thickness, poor
sticker alignment, or non-flat foundations), all warp
results because of wood factors and sawmilling pro-
cedures. Cup is a result of rewetting partially-dried
lumber or over-dried lumber.
Freedom from Casehardening
(Drying Stresses)
The procedures for proper stress relief (also called
conditioning) require the rapid addition of moisture
to the lumber surface when the lumber is warm.
Often the heat in the steam used for stress relief will
increase the kiln temperature above the required
level, leading to poor relief. Use of water to cool the
steam or cooling the lumber prior to steaming should
be considered. Using 180 F air temperature (often
called the dry-bulb temperature) is suggested. Note
that stress relief will be erratic if the lumber’s MC is
not uniform when stress relief begins. Water spray
systems can be used in lieu of steam spray. Solar
kilns do not require stress relief, as the nighttime
high humidities provide freedom from casehardening.
Good Color
By far, the most critical factor determining lumber’s
color (or discoloration) is log freshness. Old logs
have 20 times or more risk of developing stain–fun-
gal stains, sticker stains, browning, pinking, graying,
and so on. Freshly sawn lumber requires low humidi-
ties, low temperatures and brisk velocities imme-
diately after stacking and until the lumber is under
30% moisture content to control stain. Narrow loads
and partially-filled dryers will help. Poor stacking and
exposure to rain increase the risk of stain.
High Strength
Low humidities and low dryer temperatures will
maximize the strength. Other strength-lowering
factors, including bacterial and fungal effects and
species effects, are beyond our control.
Good Machinability
Wood that is too wet will fuzz. Wood that is too dry
(under 6% MC) will chip, split, and develop other
machining defects. Make sure that you monitor the
driest pieces of wood in the dryer as well as the wet
ones–don’t underestimate the effect of over-drying
on machining. Avoid temperatures over 160 F and
avoid very low humidities in the drying schedule.
(Conditioning or setting the resin at 180 F is accept-
able, however.)
Good Gluability
Good gluing requires accurate final MCs. Check for
pieces that are too wet (typically over 8.0% MC is
too wet), and too dry (under 5.5% MC is too dry).
Avoid temperatures over 160 F in the main drying
schedule. (Conditioning or setting the resin at 180 F
is acceptable, however.)
ADDITIONAL QUALITY CHARACTERISTICS
OF THE DRYING PROCESS
21

22
Oven-drying
In the oven-dry test, a small piece of wood (called a
moisture section) representing a large piece of lum-
ber is first weighed. The weighing is typically to the
closest 0.01 ounces, so a postal scale is not accu-
rate enough. Then the moisture section is put in an
oven heated to 215 F. (A kitchen-type microwave
can also be used if the oven has a carousel tray, and
is set to medium low for 20 to 40 minutes. Do not
leave the oven unattended, however, as the section
sometimes may begin to smoke.) After approximately
24 hours, the section is weighed again, dried for one
more hour, and then weighed again. If these two
final weights are the same, then all the moisture has
been evaporated; the section weight is the oven-dry
weight. The MC is calculated using this formula:
An alternate formula is:
Electric Meters
The oven-drying test is a destructive test and
requires 24 hours to get the reading. The MC can
be measured rapidly and non-destructively by using
electrical methods. It was discovered years ago
that the electrical resistance is fairly well-related to
MC. With the meter, pins are driven into the lumber
and the resistance between the pins is measured.
A second relationship was discovered between the
dielectric coefficient and the MC. Meters based on
this principle use a flat plate that is intimate contact
with the wood.
Both types of meters are fairly accurate estimators of
the MC. Each also has certain advantages and
certain disadvantages. For example, the resistant
meter can measure a gradient, depending on how
far the pins are driven into the lumber. The resis-
tance meter also is not strongly affected by different
species. The dielectric meter is not affected by the
temperature of the wood. The dielectric meter can
also quickly scan the lumber’s surface looking for
wet spots or wet pieces. Anyone kiln drying wood
needs to have both types of meters—the best meter
is always the same one that your customer is using!
The disadvantage of both meters is that they can-
not be accurately used above 30% MC. That means
that they cannot be used to run a kiln drying lumber
“green from the saw.” The oven-drying procedure is
the only reliable MC measuring system for kiln oper-
ation in most cases.
% MC = ------------------------------------------ x 100
(wet weight — oven-dry weight)
(oven-dry weight)
% MC =
[----------------------- — 1]x 100
(wet weight)
(oven-dry weight)
SUMMARY
• Lumber drying is an easy, profitable manufacturing technique.
• Air-dried lumber must be stacked correctly, protected from the
elements, dried at the correct rate, and dried to the correct MC.
• If proper procedures are used, the lumber will be flat, bright, and
free from cracks, checks, and splits.
MEASURING MC
Moisture content is a key parameter in wood processing. The MC values are measured daily when operating
a dry kiln. Depending on the MC, the temperature may be raised or the relative humidity lowered. In the dried
product, any change in MC is accompanied by warping, shrinkage (moisture loss), and swelling (moisture
gain). As a result, it is important to measure the MC accurately.
Moisture is measured in two ways: oven-drying and electrically.
2
22

23
ADDITIONALRESOURCES
3Drying
Drying Source Book: 40 Years of Drying
Experience
Edited by E. M. Wengert and R. Toennisson.
Available from Forest Products Society, 2801
Marshall Ct., Madison, WI 53705.
Drying Hardwood Lumber,
By J.Denig, G. Wengert and W. Simpson.
Available (free) from Publications Department, Wood
Eduction & Resource Center, 301 Hardwood Lane,
Princeton, WV 24740.
Drying Oak Lumber,
By E.M. Wengert.
Available from University of Wisconsin--Forestry
Dept., 1630 Linden Dr., Madison, WI 53706.
Opportunities for Dehumidification Drying of
Hardwood Lumber
By E.M. Wengert & Others
Available from Virginia Forest Products Association,
P.O. Box 160, Sandston, VA 23150.
Applied Drying Technology, 1988 to 1993; and
Applied Drying Technology, 1978-1988,
By M. R. Milota and E.M. Wengert.
Dry Kiln Operator's Manual
Edited by W. T. Simpson and Others.
Dry Kiln Schedules for Commercial Woods
By R.S. Boone and Others. Available from Forest
Products Society, 2801 Marshall Ct., Madison, WI
53705.
Design and Operation of a Solar-Heated Dry Kiln
By Brian Bond.
Publication 420-030, Dept. of Wood Science and
Forest Products, Virginia Tech, Blackburg, VA 24061.
Web Site: www.woodweb.com
(Sawing and Drying Message Board)
Sawing and Grading
Rules for the Measurement & Inspection of
Hardwood and Cypress
Written by and available from NHLA,
P.O. Box 34518, Memphis, TN 38184.
NHLA Inspection School Manual
Written by and available from NHLA,
What is hardwood? How is it graded?
(14-minute video)
Produced by and available from NHLA,
Basics of hardwood lumber grades
(10-minute video)
Produced by and available from NHLA, P.O. Box
34518, Memphis, TN 38184.
Small Sawmill Handbook: Doing It Right and
Making Money
Written by Joe Denig
Available from the Forest products Society,
2801 Marshall Ct. Madison, WI 53705.
Sawing, Edging and Trimming Hardwood Lumber
By Joe Denig and Gene Wengert.
Available from the Forest products Society,
2801 Marshall Ct. Madison, WI 53705.
Lumber yard insects (22-minute video)
Produced by and available from NC State University,
Campus Box 7603, Raleigh, NC 27695-7603.
Wood Using Industries
Directories are usually issued by most state every
few years. Contact the state Department of Natural
Resources, Forest Products Utilization Specialist.
Web Site: www.woodweb.com
(Sawing and Drying Discussion /Message Board).
Sawmill & Woodlot Management magazine
(targeting small producers).
Subscription information available at
www.sawmillmag.com
PART 3 Additional Resources
Contact the sources listed to determine availability and cost.
Most of the items listed will require prepayment.
23

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Copyright 2005 Wood-Mizer Products, Inc.
8180 West 10th Street
Indianapolis, IN 46214
800.553.0182
woodmizer.com

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