1. This document provides a method for determining the consistency of dry weight in plasterboard production by measuring the weight of consecutive boards and analyzing the data. 2. The method involves numbering over 100 consecutive boards directly after cutting, weighing each board, and calculating the mean dry weight and standard deviation to determine consistency levels ranging from excellent to unacceptable. 3. Fourier analysis of dry weight data can also help identify normal production cycles or reasons for inconsistent cycles like process changes or non-uniform drying. Safety precautions and required equipment are also outlined.

1. Lafarge Process Kit
Methods
Version 1
Direction Industrielle
Direction Assistance des
Procédés
Dry Weight Consistency
Test
Page : 1/7
Date : February 13
th
,
2007
© Copyright 2006, Lafarge Plâtres
All rights reserved. No part of this document may be reproduced, stored in a retrieval system, translated, or transmitted in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without prior written permission of Lafarge Plâtres. CONFIDENTIAL The information contained herein is confidential and proprietary to
Lafarge Plâtres. It may not be disclosed or transferred, directly or indirectly, to any third party without the explicit written permission of Lafarge Plâtres
SUMMARY
1 PURPOSE............................................................................................................................. 1
2 FIELD OF APPLICATION...................................................................................................... 1
3 PRINCIPLE ........................................................................................................................... 2
4 PURPOSE............................................................................................................................. 4
4.1 Dry weight consistency and Benchmarking indicator ...................................................... 4
4.2 Determination of normal or abnormal cycles................................................................... 4
5 SAFETY................................................................................................................................. 4
6 EQUIPMENT ......................................................................................................................... 5
7 WORKING INSTRUCTIONS ................................................................................................. 6
7.1 Boards numbering .......................................................................................................... 6
7.2 Boards weighing ............................................................................................................. 6
7.3 Data analysis .................................................................................................................. 7
1 PURPOSE
• Determinate the consistency of the Dry Weight,
• Have an indicator for the benchmarking.
2 FIELD OF APPLICATION
All LAFARGE Gypsum Division plasterboards production sites.

2. Lafarge Process Kit
Methods
Version 1
Direction Industrielle
Direction Assistance des
Procédés
Dry Weight Consistency
Test
Page : 2/7
Date : February 13
th
,
2007
© Copyright 2006, Lafarge Plâtres
All rights reserved. No part of this document may be reproduced, stored in a retrieval system, translated, or transmitted in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without prior written permission of Lafarge Plâtres. CONFIDENTIAL The information contained herein is confidential and proprietary to
Lafarge Plâtres. It may not be disclosed or transferred, directly or indirectly, to any third party without the explicit written permission of Lafarge Plâtres
3 PRINCIPLE
Measure the dry weight of consecutive boards and analyze the data (standard deviation,
Fourier analysis…). The minimum number of consecutive boards to collect depends on the
speed of the line and the length of the boards. The sampling duration is at least 250 seconds
and the minimum number of consecutives boards to collect is at least 100. The test has to be
performed with the STD board of the country. For line speed up to 60m/mn, the number of
boards to collect is determined as follow :
L
V
N
×
×
=
60
250
With :
- N : Number of boards to collect,
- V : Line speed (m/mn),
- L : Length of standard board (m).
• Number of consecutive boards to collect with STD boards length of 2,5m.
STD Speed line
(m/mn)
STD board length
(m)
Sampling duration
(s)
Minimum number of consecutive
boards to collect
15 2,5 1000 100
20 2,5 750 100
25 2,5 600 100
30 2,5 500 100
35 2,5 429 100
40 2,5 375 100
45 2,5 333 100
50 2,5 300 100
55 2,5 273 100
60 2,5 250 100
65 2,5 250 108
70 2,5 250 117
75 2,5 250 125
80 2,5 250 133
85 2,5 250 142
90 2,5 250 150
95 2,5 250 158
100 2,5 250 167
105 2,5 250 175
110 2,5 250 183
115 2,5 250 192
120 2,5 250 200
125 2,5 250 208
130 2,5 250 217

3. Lafarge Process Kit
Methods
Version 1
Direction Industrielle
Direction Assistance des
Procédés
Dry Weight Consistency
Test
Page : 3/7
Date : February 13
th
,
2007
© Copyright 2006, Lafarge Plâtres
All rights reserved. No part of this document may be reproduced, stored in a retrieval system, translated, or transmitted in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without prior written permission of Lafarge Plâtres. CONFIDENTIAL The information contained herein is confidential and proprietary to
Lafarge Plâtres. It may not be disclosed or transferred, directly or indirectly, to any third party without the explicit written permission of Lafarge Plâtres
Number of consecutive boards to collect with STD boards length of 8 feet.
STD Speed line
(ft/mn)
STD board length
(ft)
Sampling duration
(s)
Minimum number of consecutive
boards to collect
49 8 975 100
66 8 732 100
82 8 585 100
98 8 488 100
115 8 418 100
131 8 366 100
148 8 325 100
164 8 293 100
180 8 250 100
197 8 250 103
213 8 250 111
230 8 250 120
246 8 250 128
262 8 250 137
279 8 250 145
295 8 250 154
312 8 250 162
328 8 250 171
344 8 250 179
361 8 250 188
377 8 250 197
394 8 250 205
410 8 250 214
427 8 250 222

4. Lafarge Process Kit
Methods
Version 1
Direction Industrielle
Direction Assistance des
Procédés
Dry Weight Consistency
Test
Page : 4/7
Date : February 13
th
,
2007
© Copyright 2006, Lafarge Plâtres
All rights reserved. No part of this document may be reproduced, stored in a retrieval system, translated, or transmitted in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without prior written permission of Lafarge Plâtres. CONFIDENTIAL The information contained herein is confidential and proprietary to
Lafarge Plâtres. It may not be disclosed or transferred, directly or indirectly, to any third party without the explicit written permission of Lafarge Plâtres
4 PURPOSE
4.1 Dry weight consistency and Benchmarking indicator
The dry weight consistency is given by ratio between Standard deviation and Mean Dry weight
(see following table).
Std deviation / dry weight
(%)
Comment
Under 0,75 Excellent
Between 0,75 and 1 Good
Between 1 and 1,5 Usual
Between 1,5 and 2 Poor
Greater than 2 Unacceptable
4.2 Determination of normal or abnormal cycles
In case of dry weight inconsistency, the Fourier analysis can help to determine the reasons for
that (see Method “Dry weigh consistency analysis”). But, even if the indicator is excellent,
good or usual, it is important to analyse the dry weight consistency in order to determine the
normal cycles.
5 SAFETY
The identification of the consecutives boards have to be performed just after the board cutter.
To identify the plasterboards, the technician in charge of the test must be supported by one
production operator who will be closed to the emergency stop button. Furthermore, besides the
usual personal safety equipment, the technician must wear safety gloves.

5. Lafarge Process Kit
Methods
Version 1
Direction Industrielle
Direction Assistance des
Procédés
Dry Weight Consistency
Test
Page : 5/7
Date : February 13
th
,
2007
© Copyright 2006, Lafarge Plâtres
All rights reserved. No part of this document may be reproduced, stored in a retrieval system, translated, or transmitted in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without prior written permission of Lafarge Plâtres. CONFIDENTIAL The information contained herein is confidential and proprietary to
Lafarge Plâtres. It may not be disclosed or transferred, directly or indirectly, to any third party without the explicit written permission of Lafarge Plâtres
6 EQUIPMENT
For the measurements, it is necessary to have :
- One scale + 2 long steel bars to
support boards (vertical scale is
also possible) :
- Manual method :
Manual report + Excel calculation
Sheet
- Automatic method (optional) :
One PC + acquisition system
connected to the balance in order
to record automatically weight :
Remarks :
Before each test, the scale has to be checked.

6. Lafarge Process Kit
Methods
Version 1
Direction Industrielle
Direction Assistance des
Procédés
Dry Weight Consistency
Test
Page : 6/7
Date : February 13
th
,
2007
© Copyright 2006, Lafarge Plâtres
All rights reserved. No part of this document may be reproduced, stored in a retrieval system, translated, or transmitted in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without prior written permission of Lafarge Plâtres. CONFIDENTIAL The information contained herein is confidential and proprietary to
Lafarge Plâtres. It may not be disclosed or transferred, directly or indirectly, to any third party without the explicit written permission of Lafarge Plâtres
7 WORKING INSTRUCTIONS
7.1 Boards numbering
The boards numbering has to be done just after the board cutter and before the entrance into the
dryer. Then, these plasterboards are getting back at the outlet of the bundler.
Remarks :
- During the measurement, it is necessary to have no process changes (constant line speed,
mixer speed, receipt…) and to have an homogenous drying (see “moisture grid” method),
- For high line speed plants (up to 70m/mn), if the manual numbering is too difficult to do, it
is possible to use the electronic printing (grey side) on condition that the seconds are
printed
7.2 Boards weighing
The plasterboards are weighing and the weights are recorded in an Excel® compatible file.

7. Lafarge Process Kit
Methods
Version 1
Direction Industrielle
Direction Assistance des
Procédés
Dry Weight Consistency
Test
Page : 7/7
Date : February 13
th
,
2007
© Copyright 2006, Lafarge Plâtres
All rights reserved. No part of this document may be reproduced, stored in a retrieval system, translated, or transmitted in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without prior written permission of Lafarge Plâtres. CONFIDENTIAL The information contained herein is confidential and proprietary to
Lafarge Plâtres. It may not be disclosed or transferred, directly or indirectly, to any third party without the explicit written permission of Lafarge Plâtres
7.3 Data analysis
Calculate with Excel :
- Mean dry weight,
- Standard deviation,
- Standard deviation/Mean dry weight ratio (%).
Determinate the level :
Std deviation / dry weight
(%)
Comment
Under 0,75 Excellent
Between 0,75 and 1 Good
Between 1 and 1,5 Usual
Between 1,5 and 2 Poor
Greater than 2 Unacceptable
To find the normal cycles for Excellent, good and usual levels or to determinate the reasons of the
poor and unacceptable levels, see “Dry weight consistency analysis” method.