Wood preservation techniques and prospects

1
Forest Research Institute ,
Indian Council of Forestry Research and Education
Dehradun , tripathis@icfre.org
Wood Preservation: Issues and
prospects
6/4/2020
By
Sadhna Tripathi,
Scientist

6/4/2020 2
FOREST PRODUCTDS RESEARCH
AIMED AT
•Efficient utilization of forest resources to meet
the needs of mankind through wood based
industries
•Guiding forestry research and forest
programmes to ensure sustainable supply of
raw material for forest based industries, while
protecting the environment and maintaining
the ecological balances

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WOOD PRESERVATION PROTECTION
AGAINST SEVERAL TYPES OF WOOD
DESTROYING AGENTS –
Natural durability of about 200 species and treatability
of about 150 species have been studied
Classification of species based on their durability and
treatability
Development of world class wood preservatives ASCU,
[COPPER CHROME, ARSENIC], CCB
Development of non leachable type fire retardant cum
preservatives

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Wood anatomy
Timber mechanics &Timber engineering
Wood seasoning
 Wood preservation
 Wood working and finishing
Chemistry of wood & other forest
products
DISCIPLINES OF WOOD SCIENCE

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Surface coating, smoking, bitumen
coating for interior use
Impregnation by hot and cold
method
Impregnation by chemicals under
high vacuum and pressure
Development of environ -friendly
wood preservative
INNOVATIONS IN METHOD OF TREATMENT

Wood protection with special
reference to preservation
Types of wood Service life months No. of species
Durable : Class 1 120 and over 120
Moderately durable
Class :2
60 and over but less than 120 55
Non durable
Class:3
less than 60 153
Natural durability of timber
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Use Life Untreated
(Years)
Life Treated (Years)
Mines 2 10
Ground contact in the
open
5 25
Out of ground contact open 10 40
Marine waters 2 10
Cooling towers 3 15
Inside location
(ground contact )
8 40
Inside location
(out of ground contact )
15 50
Life expectancy after treatment for different end uses
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Natural Durability and heart wood
Heartwood only
Varies with age and height
Varies from tree to tree
Second growth can have reduced
decay resistance
Extractives in heartwood
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Wood preservation –An efficient tool
to prevent biological attack on wood
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A preservative may be defined as a substance
which when suitably applied to the wood makes it
resistant to attack by fungi, termite and insect

What is the Need of preserving wooden material ?
Because of Bio-deterioration , mainly due to
1. Biological
degradation
Microbes
1.White rot
2.Brown rot
3. Sap stain
4. Soft rot
Insects
Termites
Borers
Powder post
beetles
Marine borers
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Fungal Degradation :
Certain lower forms of fungi develop as molds and stains
 The most important stain is blue stain,.
Such attack is confined basically to sapwood of certain wood
species, rich in starch content.
freshly cut wood which contains a high moisture content.
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Wood Rot or Decay Fungi :
These are the fungi, which thrive on wood substance.
Wood decay can occur both during storage or use
Wood is food source
Favourable conditions for decay are :
(I) optimum temperature 16 to 320 C,
(ii) moisture 35-45 per cent
(iii) supply of air and (iv) food.
*Some fungi are active even at 450 C.
*Although high temperature for prolonged periods may
kill the fungus, at lower temperature, they become
dormant, ready to attack whenever favourable conditions
occur.

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Wood rotting fungi are sub-divided into three main types.
White rot : cellulose, hemicellulose and lignin.

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Brown rot :
 consume carbohydrates, i.e. cellulose and
hemicellulose.
 Lignin is not much affected.
 Many of the brown-rot fungi produce bracket-shaped
fruitbodies on the trunks of dead trees,
 the decaying wood is brown and shows brick-like
cracking

Soft rot :
Wood is attacked on surfaces exposed to high humidity or in
contact with moist soil.
Such fungi have optimum growth in acidic (pH 6-7) conditions,
some can grow in alkaline conditions (pH 7-8) at which growth
of most decay fungi is inhibited.
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Prevention Methods
Keep wood dry
Coat wood
Alter wood/moisture relationships
Poison wood (natural or artificial)
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We ARE HERE

Protection of felled timbers: Non chemical
methods:
safest felling period : winter season when
most of the borer's beetles are in dormant
or in immature
debarking of logs
logs submerging in log ponds
prophylactic chemical treatment
Timber Can Be Protected At Various Stages
Since Harvesting
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Protection against end cracking :
As wood dries, the surface fibers give up their moisture
first and tend to shrink but are restrained from so doing by
the interior fibers, which have not begun to shrink; thus
drying stresses develop that tend to cause checks
It can therefore be avoided by employing suitable
moisture barriers commonly known as end-coatings in the
trade . A uniform coat on transverse surface near the ends .
Coal-tar, F.R.I. anti splitting cum preservative coating,
wax coating (paraffin and wax emulsion) , aluminium
paint, linseed oil mixed paint latex based .
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PROTECTION OF WOOD :
Two different types of protection methods
have been developed
(i) Short term protection during
transportation/storage
(ii) Long term protection during the service
life of the wood product
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Short term protection:
The logs or planks should be given a brush , spray or
dip treatment with insecticide plus anti sap stain chemical
Stored under shade on a clean place on the piles of
treated wood or cement concrete
 Remedial treatment : against sap stain and termites.
Prophylactic treatment are given either by spraying
of 3% borax boric acid ( 1:1) for sap stain
 for all microbes and insects : Sodium
pentachlorophenol, chlorinated hydrocarbon like
gamma BHC (Lindane) 1%, aldrin 0.5% etc.
206/4/2020

Type of preservative Chemicals tested
Oil type Creosote coal tar creosote fuel oil
(50:50),creosote fuel oil (25:75),LTC fuel oil
(50:50),Arsenical creosote etc.
Organic solvent type Copperresinate, Copperised
CNSL,Copperised BNSL, Borated CNSL etc.A
new formulation based on copperresinate and
CNSL. Copper nephthenate, zinc napthenate,
PCP , TCP etc.
Water borne type Fixed Type : Ascu (CCA) ,CCB,ACC ,BCCA
Ammonical copper arsenate ACA
Water soluble non fixing type : Zncl2,boric
acid, boric acid and borax,sodium fluoride,
sodium penta-chlorophenate. BHC Water
dispersible powder Spray for prophylactic
Treatment
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Oil type:Coal tar creosote
oil type preservative.
brownish black liquid by product coal tar..
It is recommended for exterior use as it is highly
non-corrosive to metals and protects timber against
splitting
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Water Soluble Type:
Leaching type : For interior locations
Chemicals such as Zinc chloride, Boric acid and
Borax, copper sulphate, Sodium pentachlorophenate
(NaPCP)
Fixed Type: For exterior uses These preservatives
are mixtures of various salts , react and form
insoluble complex salts and thus get permanently
fixed in wood .
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ENVIRON - SAFE WOOD PRESERVATIVE
ZiBOC
PatentNo. :257393 Granted on28.9.2013,
BIS accepted to includein BIS: 401
Results revealed it’s efficacy comparable with CCA.
Treatment of plantation species with ZiBOC will justify
the necessity of treatment of nondurable species for long
lifespan products and will also suggest an alternative to
toxic preservative.
No specific requirement for the treatment is required. All
procedures opted for CCA are same in ZiBOC also.
All routine methods were followed in bamboo and wood
treatment with ZiBOC

ZiBOC treated chir pine planks and battents and eucalyptus poles
20082010
2019 2006

CCA( By weight)
CuSo4 37.5
Na2Cr2O7 .2H2O 50
As2O5 . 2H2O 12.5
CCB: Copper Chrome Boric composition
Copper Sulphate 3 parts
Boric acid 1.5 parts
Sodium dichromate
or
Potassium dichromate 4parts
276/4/2020

Long term protection:-
1.Impregnating inorganic/organic toxic compounds in
the timber to make the wood material poisonous to
fungus and insects.
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Hot and cold process:
The process is suitable for easy-to-treat species ( a & b class
treatability).
The timber to be treated, is heated in preservative solution to
about 90oC for 2 to 3 hours.
Pressure treatment processes :
Impregnation of wood under pressure is the most desirable and
best method to get uniform and proper treatment under controlled
conditions.
This is usually done in a pressure cylinder equipped with vacuum-
pressure system, storage tanks and mixing tanks for preservative
solutions.
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Full Cell Process:
 For high absorptions of the preservative
vacuum of at least 56 cm of mercury is created
and maintained for half an hour.
cylinder is filled with the preservative,
cylinder is subjected to an antiseptic pressure of
3.5 to 12.5 kg/cm2
The pressure is held until the desired absorption is
obtained,
preservative is withdrawn finally a vacuum of 38
to 56 cm of mercury for about 15 min. is applied

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Current state of the art for impregnation systems

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3 TYPES OF PRESERVATIVES
7 METHODS OF TREATMENT
8 CHOICE OF TREATMENT
ANNEX B( Clause 8.3) DURABILITY AND DEGREE OF
TREATABILITY OF DIFFERENT SPECIES OF TIMBER
ANNEX D( Clause 9.5)MEHTOD FOR THE
DETERMINATION OF PENETRATION OF PRESERVATIVE
IS : 401 PRESERVATION OF TIMBER

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Method for the determination of penetration and identification of
preservative by spot test : CCA/CCB/ZiBOC composition
0.5 g chrome Azurol-S, 5.0 g of sodium acetate in 80 ml water and
dilute to 100 ml. A deep blue colour shows the presence of copper.

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3.0%
4.5%
6.0%
TESTING OF PRESERVATIVE /CHEMICAL EFFICAY /
TRETED WOOD IN FIELD AGAINST TERMITES IN
MOUNDS

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Condition Commodity Process Preservative Retn.kg.
m3
Building internal
use but in contact
with ground soil
or under humid
conditions
Doors, windows
Frames, ceilings,
trusses, columns,
pole support
Hot and cold
process
treatment of
green timber
& pressure
processes
CTC/LTC
CCA/BCCA
ACC
CCB
PCP
Boric acid:Borax
(1:1)
80
6.5
6.5
6.5
5
6.5
Building timber or
timbers in interior
use not in
contact with
ground
or soil and used in
dry condition
Doors, windows,
frames,false-
ceiling,
purlins, pelmet, etc
CTC/LTC
CCA/BCCA
CCB
PCP
Boric acid
:boric (1:1)
80
4
4
5
5
Furniture, cupboard.
chicks, etc
Two liberal
brush coats
or momentary
dipping
PCP 5%
PCP 5%
Boric acid : Borax
(1:1)
RECOMMENDED PARCTICE FOR PRESERVATION OF
TIMBER

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CODE OF PRACTICE FOR ANTI-TERMITE MEASURES IN
BUILDINGS: IS 6313 (Part 3) :2001
3.4 Wood Treatment : The application of chemical termiticides to
woodwork and wood-based materials to eliminate existing termite
infestation and to make it resistant to termite attack.
4.1 Any one of the following chemicals conforming to relevant Indian
Standard in water emulsion maybe used for the soil treatment in order to
protect a building from termite attack. Chemical Relevant Indian
Concentration by Standard Weight, Percent (Active Ingredient)
Chemical Relevant Indian Concentration by Standard
Weight, Percent
(Active Ingredient)
Chlorpyrifos 20 EC : IS 8944 1.0
Lindane 20 EC : IS 632 1.0
4.1.1 Oil or kerosene based solution of chlorpyrifos 20 EC or Lindane
20 EC 1.0 percent (by weight) concentration is useful for treatment of
wood.

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5.3.1.6 : Treatment at points of contact of woodwork .
woodwork in contact with the floor or walls ,infested by
termites, shall be treated by spraying at the points of
contacts with the adjoining masonry
The treated holes shall than be sealed.
5.3.2.1 The woodwork which has already been damaged
beyond repairs by termites shall be replaced.
5.3.2.2 Infested woodwork in CHAUKATS, shelves,
joints, purlins, etc, in contact with the floor or the walls
shall be provided with protective treatment

6/4/2020 45
Field testing of preservatives using stakes
305 mm in length
and 38.1 mm cross
section
Treatment 3 different
levels of absorption
The specimens are
buried half below and
half exposed above the
ground

6/4/2020 48
SEASONING AND MOISTURE CONTENT :IS 12896 : 1990
Classes depending upon their behavior with respect to
cracking and splitting and drying rate:
a) Class A : Highly refractory : slow and difficult
to season free from surface and end cracking.
b) Class B : Moderately refractory : seasoned
within reasonably short periods
c) Class C: Non-refractory : rapidly seasoned free,
If not rapidly dried, they develop blue stain and
mould on the surface

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MOISTURE CONTENT OF TIMBER ANDTIMBER
PRODUCTS - METHODS FOR DETERMINATION
DETERMINATION OF MOISTURE CONTENT BY OVEN-DRYING
METHOD
Test specimens consisting of a crosssection,15 mm to 20 mm long in
the direction of the grain, free from all defects,
The weighed test specimens shall be oven dried at 103 * 2°C for a
sufficient period, usually 12-18 hours and two or three control pieces
shall then be weighed and returned to the oven for further drying.
Successive mass of these control pieces shall then be taken after every 2-
3 hours. When changes in successive mass cease to be less than 0.02 g
for

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Calculation:
The moisture content of each sample shall be determined by the
following formula:
Wi -W0
M = -------------x 100
W0
Where M = moisture content ( percent ),Wi = initial mass of test
specimen ( in g ), and w0= oven-dry mass of test specimen( in g )

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Name of Durabi- Treat- Refrac- Name of Durabl- Treat- Refrac-
Species lity ability t oriness Species lily ability toriness
10 to
Seasoning Seasoning
Super Group Dysoxylum mala- I B
Albtzt« lebbeck I e B
baricum ( white cedar)
( kokko ) Glut a travencorica I
Albizia odoratissima I e B
( gluta )
Michelia sp. II A( kala siris )
Chukrasia
velutina II c B
( champ)
Phoebe haincsianu I! c B
( chickrassy )
( bonsam )
Dalber gta latifolia 1 B Pterocarpus .lalberg- c B
( rosewood) ioides ( padauk )
S. Dalbergia
sissoo I e B Tectona grandis I e B
( sissoo ) ( teak)
INDIAN TIMBERS FOR DOOR AND WINDOW SHUTTERS
AND FRAMES IS 12896 : 1990 SUPER GROUP TIMBERS FOR
SHUTTERS

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GROUP I TIMBERS FOR FRAMES
Name of Durability Treat-
ability
Refrac-
torinessto
Seasoning
Species
Albtzta lebbeck I e B
( kokko )
Albiz'a odoratissima I e B
( kala siris )
Albizla procera I c B
( safed siris )
Aphanamixls polys- I B
tachya ( pitraj )
Artocarpus hetero- I B
phy/!us ( kathal )
Name 0/
Species
Durability Treat-ability Refractoriness
to
Seasoning
Artocarpus hirsutus
( aini )
I B
Artocarpus lakoocha I
B
Cedrus deodara I c C
( deodar)
Dalbergia lattfolta I B
( rosewood)
Dalbergia sissoo I e B
( sissoo ) 1/7/2019

6/4/2020 53
GROUP II TIMBER FOR FRAMES
SI Name of Dur abi- Treat- Refr~c- S/ Name of Durabi- Treat- Refrac-
No. Species lily ability toriness No. Species lity ability toriness
10 10
Seasoning
Seasonin
g
I. Acacia nilotica II b B 13. Mangifera indica III a B
(babul ) (mango)
2. Adina cordifolia III a B 14. Mitragyna parviflora III b B
( haldu )
(kaim)
3. Anihocephalus
chin-
III a C
15. Phoebe hainesiana II c B
ensis ( kadam )
4. Castanopsts sp. II b B ( bonsum)
16. Pinus roxburghii III b(Indian chestnut) C
S. Chukrasia velutina II c B ( chir )
( chickrassy ) 17. Termina/ia arjuna II b B
6. Cullema rosayroana III b C ( arjun )
( karani ) I e C 18. Termtnalia bellirica III b B
7. Cupressus torulosa (bahera)
( cypress) 19.Terminalia chebula
( myrobalan )
II c A
'8. Dipterocarpus macro- III a B
carpus ( hollong ) 20.Terminal'a manii
( black chuglam )
II a B
9. Dipt,rocdrpus sp. II b B
( gurjan)
10. Gmt/ina arborea I e B 21.Terminalta myrio-
carpa ( hollock )
III a B
(gamari)
11. Hevea brasiliensis III b B 22.Termlnalla procera
( white bombwe )
III b B
( rubberwood )
12. Holoptelea tntezrt.. III b B
23. Toona ciliata ( tOOD) ]1 c B

6/4/2020 54
TIMBER DOOR, WINDOW AND VENTILATOR FRAMES — SPECIFICATIONIS
4021 : 1995TIMBER BEING IMPORTED FOR FRAMES OF DOORS AND WINDOWS CONSIDERED
SUITABLE FROM THE FOREIGN LITERATURE AVAILABLE
Sl No. Trade Name Botanical Name Country from
Where Imported
(1) (2) (3) (4)
i) Abura Mitragyna stipulosa Africa (A)
ii) Afrormosia* Afrormosia angolensis (A)
iii) Alan Batu† Shorea albida Malaysia (M)
iv Amoora† Ammore cucullata Papua New Guinea
(PNG)
v) Bitangor Calophyllum spp. (M)
vi) Dark Red Meranti† Shorea spp. (M)
vii) Durian Coelostegia spp. (M)
Duria spp. and
Neesia spp.
viii) Iroko* Chlorophora excelsa (A)
ix) Keuring Diapterocarpus spp. (M)
x) Kwila† Instia bijuga (PNG)
xi) Light Red Meranti† Shorea spp. (M)
xii) Merawan† Hopea spp. (M)
xiii) Merbau† Intsia palembanica (M)
xiv) Nyatoh† Ganua spp., Palaquium spp. and (M)
Payuena spp.
xv) Nyatoh kuring† Planchonella spp. and (M)
Pouteria spp.

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INDIAN TIMBERS FOR FURNITURES AND CABINETS -
CLASSIFICATION :13622;1993

6/4/2020 58
Fumigation….?
•Pant H. and Tripathi S. (2011) Fumigation of wood with aluminium phosphide
for protection against fungi. Journal of Tropical Forest Science, 23(4): 363-370.
•H. Pant. and Sadhna Tripathi (2012): Effect of copperised (II) neem leaves
extractive complexes on wood destroying termites. Journal of Entomological
Research. 36 (2) :147-150.
•H. Pant and Sadhna Tripathi (2011): Potentials of neem seed oil in wood
protection through fumigation. J.of Eco-friendly Agriculture. 6(1): 84-89.
•H. Pant and Sadhna Tripathi (2011): Effect of neem seed oil as fumigant on wood
destroying insect. International Wood Products Journal (UK) .2(2): 95-100.
•H. Pant and Sadhna Tripathi (2010): Fungal decay resistance of wood fumigated
with chlorpyrifos. International Biodeterioration & Biodegradation (USA). 64:
665- 669.
•Pant H. and Tripathi S. 2010. Fungal decay resistance of wood fumigated with
chlorpyrifos. International Biodeterioration and Biodegradation, 64 (7) 665-669.
•Evaluation of Aluminum Phosphide Against Wood-Destroying Insects J. Econ.
Entomol. 105(1): 135Ð139 (2012)
Laboratory study

6/4/2020 59
No field trials or pilot scale testing
Need to develop new chemicals of
environ-safe nature
Discussions
are required
for future
strategies

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