LY
MLLS
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Forcst
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IDIhcIoy Spcíól
Is12 No.
J
UNITED STATES DEPARTMENT OF AGRICULTURE
AGRICULTURAL RESEARCH ADMINISTRATION
BUREAU OF PLANT INDUSTRY,
SOIL3. AND AGRICULTURAL ENGINEERING
DIVISION OF FOREST PATHOLOGY
MADiSON 5, WISCONSIN
IN COOPERATION WITH THE
FOREST PRODUCTS LABORATORY
FOREST SERVICE
OREGON FOREST PRODUCTS LABORATORY
LIBRARY
(DETERIORATION OF
FIRBOARD BY
MOLDS')
By
GEORGE H
ENGLERTH, Pathologist1
Division
Bureau of Plant Industry,
Agricultural
United States
of Forest Pathology
Soils, and Agri,iltural Engineering
Research Administration
Department of Agriculture
The mold. resistance of fiberboard. has been studied to provide a
basis for recommendations on the relative merits of various types of corn-.
inercia], and of experimental ±'iberboards,
The experimental fiberboards
were prepared. by the Division of Pulp and, Paper of the Forest Products
Laboratory.
The scope of these iivestigatìons includes:
(i)
inercia].
The relative amount of deterioration of various types of corn-
fiberboard.s.
The resistance to molding of various types of laminating
(2)
adhesives used in commercial fiberboard samples.
only,
The protective value of adding a preservative to the adhesive
(3)
to the furnish only, or to both,
(4)
The ability of molds to penetrate the unbroken surfaces of
fiberboard,s,
(5)
The effect of molding
bursting strength of the boards.
and.
delamination on the tensile and
lThe writer wishes to acknowledge the assistance of R. L. Krause, formerly
pathologist In the Division of Forest Pathology, who started the study,
and, T
L, Fletcher, chemist in the Forest Products Laboratory,
In cooperation with the Forest Products Laboratory, maintained by the
Forest Service, United States Department of Agriculture, at Madison 5,
Wisconsin, in cooperation with the University of Wisconsin,
For.Path.Spec, Release No. 29
-1--
MÂTBRLALS
Forty samples of commercial fiberboard were tested.
These included
samples of Vis, V2s, V3s, V3c, W5c,W5s, and W6c, the designations as" and.
1Ct referring to solid. and. corru,atea types, respectively.
"IT" fiberboard,
rad.es l
2, and. 3,was developed primarily for exterior containers for
IFTTII
overseas shipment, often requiring high weather resistance,
board,
grades 5 and 6, also designed to withstand. moist conditions, is of lower
strength and was developed. primarily for use as interior boxes that are
overpacked. in wood or tt1ttt board for overseas shipment.
Table 1 shows the
requirements for these different rad.es as given by joint Army-Navy
Specification JAN-P-108 dated. June 1944. In most cases the fillers of
these boards were laminated with a urea-formaldehyde-starch or a ureaformaldehyde-starch-emulsified asphalt adhesive. The liners were bonded
either with these adhesives or with asphalt. Pive sales were laminated
with a proprietary polyvinyl resin adhesive and one was asphalt impregnated.
To of the boards were laminated, with ura-formaldehyde starch containing
0.08 percent sodium pentachiorophenate.
Where known, the rosin content of
the urea-formaldehyde-starch adhesive was about 6 to 8 percent based. on
the dry weight of the starch.
In addition to the commercial boards, the Division of Pulp and.
Paper of the Forest Products Laboratory provided experimental solid fiberboards with and without preservative, and with the furnish composed. entirely of reclaimed fiber.
Sodium pentachiorophenate was added to the
furnish in half of the boards prior to the addition of 3 percent rosin
and. 3 percent alum as sizing.
Two concentrations of the preservative
were tried, 1.7 and 2,0 percent.
Chemical analysis of the board treated
with 1.? percent sodium pentachlorophenate showed that 0.6 percent of the
preservative was retained.
The liners of these boards were laminated with asphalt and the
filler with a urea-formaldehyde-starch adhesive contning 20 percent
resin based on the weight of the dry starch,
Twelve and. one-half percent
ammonium chloride based on the weight of the resin was athed as a catalyzer.
TH OD S
All of the test sampleswere soaked in distilled water at room
temperature in order to raise the moisture of the boards to a content
favorable for mold deielopment.
The soaking period was varied. for the
different tìpes of ±'iberb.oards, depending on preliminary trials and. the
type of board,
The corrugated. boards were immersed. for 1/4 hour, the
solid commercia]. tensile-tested boards for 1/2 hour, the commercial and
experimental Mullen-tested, fiberboards for 4 hours, and the experimental
tensile-tested, boards for 16 hours,
The Mullen test is a common bursting
test.
Half of the samples were inoculated, by dipping then in a water
suspension of mold. sflores and. bacteria which had. previously been isolated
?orPath
Release 29
from moldy fiberboard and other cellulose material.
No attempt was made
to work with pure cultures or specific organisms, but similar inoculum was
used. throughout the tests.
The inoculated samples were incubated for
periods up to 12 weeks in a closed container stored in a room maintained
at 9? percent relative humidity and. 800 F.
Water was put in the bottom
of the container, but it did. not come in direct contact with the specimens,
The uninoculated. samples or controls were incubated in separate containers
under the same conditions except that volatile fungicides were placed in
the containers to prevent mold growth.
The fungicides used were pyridine,
paradichlorobenzene, and Insl-X Volatile
ingicide.
Some of the V-boards were edge-coated with beeswax containing 5
percent pentachiorophenol and 5 percent rosin after the initial soaking
and prior to inoculation,
The treatment was designed to prevent molding
through the edges of the board, and. thereby determine the ability of the
molds to penetrate the unbroken surface of the board,
Both the wet and dry tensile and bursting strengths of the original
boards were determined.
At regular intervals, samples of the inoculated
and uninoculated boards were removed, data on their condition recorded.,
and eïther the bursting strength or the tensile strength dstermined. One
specimen of each treatment was tested as removed from the incubation
chamber, and one after being conditioned to equilibrium at 50 percent
relative humidity and 80° P.
The moisture content of the conditioned
boards was between L and 8 percent,
Boards tested for bursting strength
by the Mullen test were punctured in 5 different places and the average
for the 5 punctures considered as the bursting strength of the sample.
Boards tested. for tensile strength were cut into four 1-by 6-inch strips
after approximately 1/2 to 1 inch was removed from each side of the board
in order to avoid excessive effect from edge molding or delamination.
The
long dimension of the strips was cut parallel with the machine direction
of the board for solid boards or parallel with the corrugations for the
corrugated boards.
SULTS ON
C0MRCIAL V-BOARD
All the commercial V-boards molded,
The amount of molding, tensile
and bursting strength values, and moisture contents are shown in table 2.
In general, the deterioration and delamination as a result of action by
organisms was not reflected in significant decreases in bursting strength.
In some cases the sample was heavily molded. and. completely delaminated
after 12 weeks exposure, but its bursting strength was still as high or
higher than the original strength, or the corresponding uninoculated
control,
Apparently little actual injury to the fibers took place during
the period. of the tests.
Tensile strength tests reflected. loss due to
molding and resultant delamination somewhat better than did the Mullen
tests.
For.Path, Release 29
-3-
possible to Beparate the possible action of bacteria from
that of molds in the deterioration and. delamination of the fiberboards. ..s
a consequence, when referring to strength loss and. delamination by molds in
this report the possible effects by bacteria are inclu.ed with those by
molds. It bas been shown that a moisture content of at least 55 percent
required. for bacteria acting alone to weaken casein-glued plywood. joints.-
It
was not
of the inconsistencies In results my lie in the lack of
uniformity in the fiberboard. Also, differences in moisture content of
those specimens testea wet may account for some of the variations in
strength values, However, moisture content is not a cause of variation in
those samples tested after being conditioned. at 50 percent relative
humidity and 800
Some
bring out more clearly the relationship of molding to strength
values, table 3 ehows the decrease in strength for each test period as coinpared. with the original strength values. For those boards in which tensile
tests were made, the decrease in strength is presented. in graphic form in
figure 1.
The amount of mold.ing ozi all V-board specimens is summarized in
table 2, and the amount of delamination in table 4. Mold development on
representative samples after 12 weeks' exposure is shown in figure 2.
To
Boards laminated. with the proprietary polyvinyl resin adhesive were
only lightly molded even after 12 weekst exposure, and. showed no delaminatian. The asphalt-irirpregnated. boards were moderately molded but not
delaininated..
All of the solid V-board samples laminated with urea-formaldehydestarch or with urea-forirldehyde-starch-asphalt emulsion molded readily
and began to delaminate after 5 weekst exposure. Some had completely
d.elaminated. after 12 weeks. The addition of 0.08 percent sodium
pentachiorophenate in the urea-formaldehyde-starch adhesive did. not
inhibit mold. growth and. the boards so treated. molded and. d.elaminated.
almost as readily as untreated ones.
The
corrugated V3 boards molded and. ä.elaminated quite readily.
rapid delamination may be explained by the presence of the corrugations,
which allowed the inoculation spore suspension to r-un into the inside of
the board..
The
of the uninoculated control samples showed any delamination
except for the corrugated. samples, which wore partially delaminated. after
12 weeks. The presence of the volatile fungicides in the containers in
which those specimens were incubated, held. molding to a minirmzn. Sinee the
None
'Duncan, Catherine G. The effect of moisture on bacterial delamination of
casein-bonded. plywood. Office Report, 10 pp. April 1946.
Por.Path. Release
29
-4-
control specimens were incubated under the same conditions with moisture
contents approxiniately the same as the molded specimens, there is little
question that the delamination of the solid boards and mast o' it in the
corrugated boards was due to mold attack on the inoculated specimens.
Penetration of Molds
One of the purposes of the study was to determine whether molds
are able to penetrate the unbroken surfaces of the fiberboard. or hethr
penetration is dependent upon breaks in the board.
In order to obtain
information on this question the edges of one set of the boards wére
sealed with a fungicidal wax before inoculation. In that way the attack
by molds was restricted to the surface plies.
Detailed notes on the
delamination after 7. and 12 weCkst exposure of the inoculated specimens
with edges exposed and with the edges sealed are given in table 4. The
samples with sealed edges generally we'e somewhat less delaminated. after
7 weeks' exposure than the unsealed samples.
After 12 weeks, however,
delamination in the sealed specimens was practically as great as in the
specimens having their edges exposed.
Delamination of the samples with
exposed edges generally progressed from the outside toward the center.
In
many casos these samples had begun to separate along the edges after 5
weeks.' exposure.
These observations indicate that the delamination of fiberboard
having no other means of eitrance for micro-organisms than penetration
through the surface pliesmay be almost as rapid as in fiberboard having
open edges.
It seems unlikely that organisms may have penetrated the wax
seal since no delamination was noted around the waxed. edges when the
plies
were separated for observation.
Small-scale penetration tests with decay fungi on fiberboard with
wax-sealed edges showed that two fungi causing brown rots grew through 72s
boards in 7 days' time. Certain molds came through V3s board in 15 days.
Prom these tests .t is readily seen that some of the adhesives
regularly used in laminating fiberboard are not resistant to attack by
micro-organisms when such fiberboard is exposed for extended periods of
time to conditions that favor mold growth.
RESULTS ON COMMERCIAL W-EOARD
The results of tensile tests and notos on
molding and delamtnatin
of W-board. are given itable 5.
After about 1 week, molding was observed
on all of the corrugate. boards, and after 3 weeks
they were heavily
molded.
Mold was about., as heavy within the corrugations as on the faces.
The solid W5 board laminated with a
proprietary polyvinyl resin adhesivé
Por. rath,
fleioaMe
9
was only lightly molded with no delamination at the end. of 12 weeks,
while the same type of board laminated. with urea-formaldehyde-starch was
heavily molded and 90 percent delaminated. after 3 weeks.
To illustrate more clearly the decrease in tensile strength of
these boards due to molding, the data in table 5 are presented. graphically
in figure 1,
Since
The tensile strength of all inoculated '1-boards was reduced.
some further loss in the inoculated boards occurred. after delamination, it
appears that the organisms present decreased the fiber strength. However,
a greater part of the decrease in tensile value was apparently due to
delamination, No delamination was noted in the uninoculated samples
incubated under similar conditions.
In evaluating the results, however,
differences in moisture content as well as differences in the strength
values of individual boards should be recognized.
RESULTS ON
EXPERINTAL FIBEBB0AR
Three sets of experimental fiberboard.s were prepared and tested
One set had 1,7 percent sodium pentachloróphenate added
against molding.
to the fiber furnish with varying amounts of this preservative added to
Chemical analysis showed, however,
the urea-formaldehyde-starch adhesive,
that only 0.6 percent of the preservative was retained in the fiber.
Another set had 2.0 percent sodium pentachiorophenate added. to the furnish
and. varying amounts of the chemical added to the adhesive, while still
another was made of untreated furnish.
The results of the Mullen tests made on the boards treated. with 1.7
percent sodium pentachiorophenate are recorded in table 6, and those of
tensile tests on boards treated with 2.0 percent preservativo are recorded
Notes on molding and. delamination and the moisture contents
in table 7,
of those specimens that were tested wet are includod in the same tables in
order to facilitate correlation of the strengths with amount of molding
and moisture content.
All the boards without sodium pentachiorophenate added to the
furnish moidd heavily, and likewise showed a greater reduction in both
bursting ath tensile strength than did boards with the furnish treated.
The loss in ensi1e strength of the experimental boards tested. is
illustrated. grap:ra1ìy tn figure 3.
The addition of 2 percent or less
t.ah1iroi1xenate in the adhesive gave little or no evidence
of sodium
The
of preventrv detero:.at.Lon and. consequent lcss in tensile strength.
incorporation oi th 2reorvat.ve in the adhesive as well as in the
furnish aids Httl to the cost and should. aid in preventing molding;
additional tests with 2 percent and. higher concentrations in the
adhesive are needed before concluding against it.
For.Path, Ro.Qabo 29
The asphalt liners tended to loosen after preliminary soaking and.
subsequent incubation. The asphalt supported. surface mold growth, which
indicates that treatment of the asphalt might also be advantageous.
Pigure 4 shows the amount of molding of the reclaimed treated and.
untreated. fiberboards after 12 weeks' incubation at 97
percent relative
humidity and. 80°
SUMMARY AN
CONCLUSIONS
Mold. tests made on various V- and W-fiberboards and
experimental
fiberboard.s gave the following results
(i) Urea-formaldehyde-starch and.
ureaforma1dehyd.e-starch-asphaltemulsion resins in solid IT- and W-board.s were not mold resistant.
(2) V-. and. W-boards laminated with a proprietary polyvinyl resin
adhesive were more mold resistant than those boards laminated with
other
adhesives, Only light molding with no delamination was noted. on
these
boards after 12 weeks.
(3) Both V and. W corrugated. boards laminated with ureaformaldehyde-starch molded. heavily and were badly delaminated. after 3
weeks,
(4) Uninoculated corrugated and solid
boards did not delaminate as
readily as inoculated. boards.
and.
(5) Molds penetrated through the
surface of the solid. fiberboard
caused delamination.
(6) The addition of 1.7 and 2.0
percent sodium pentach1orop}enate
to the furnish reduced molding
and strength loss appreciably with the
higher concentration giving the best results,
(7) The addition of 2 percent sodium
pentachiorophenate to the
adhesive gave no evidence of value when the
furnish was untreated, or of
isroving the protection when the furnish was treated.
However, until
additional evidence is available it would be safest to
treat the adhesive,
probably using a higher concentration than the 2
percent used in these
experiments,
(B) Asphalt is not mold-inhibiting and.
should. probably be treated
along with the other constituents in making
a mold-resistant board.
For.
Path, Release 29
-7-
Table l.--Requirements for V-board and W-board exterior and interior grades
Maximum
Miniimim
Solid
Corrugated fiber:permissiblo
average
fiberboard; nominal
ply
bursting
board
caliper
:
:separation
strength
:nominal
of paperboard(wet)
:
: --------------------- :oaliper: -------------After
Dry
:Outer
Inner :Corru
:24- hours:
:liners:liners;gated
immer:
:inatez
;
pe:Grado:Compliance:
symbol
:
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Exterior grades
SF
Vis....
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SF..:
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peroent minus and unlimited plus toleranoo is permitted.
Corrugations shall be "B or "0" flute having approximately 50 or +2 flutes
per foot, respectively.
For.Path.Speo.Reiease No. 29
Table 2.--Tenaile strength, bursting strength, molding, and moisture Content of commercial
V-boards subjected to molding at 97 peroént
Tensile strengtb!/
Type of
:
board:
:
Test
period
Weeks
:
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lad Control
td C'ont5Ol atd Control
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Tested wet
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Moisture content of wet boards
:
Tensile tests
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Bursting teste
of
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Vls
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relative humidity
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795
775
750
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V2e
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:
:
:
:
:
-----
z
------
:
:
s
:
:
527
360
293
370
339
:
--
:
626
637
540
568
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
-----
:
:
:
:
------
:
:
:
:
762
734
636
613
:
s
:
:
:
604
666
:
600
--
:
61$
611
604
:
597
623
:
426
:
:
$11
:
642
754
715
:
:
:
726
:
--
toll
:
329
418
:
:
11.26
:
:
:
:
:
:
:
:
:
--
:
:
578
575
561
:
66
:
--
:
:
:
364-:
:
22$
303
326
:
:
:
:
:
:
:
460
420
433
468
:
:
:
:
76k
$27
834
$03
798
601
521
6S
557
550
42$
454
45$
944
;
t
:
--
:
:Light
:I4sdiunr:
:Heavy
:Eoav'
:
:
:
;
:
---
:
:
---
:
:
--
:
:
---
:
:--.
:Light
--
:
:Medium:
:Heavy
454:Heavy
:
:
----------
:
s
:
:
:
:
30
:
:
1$
--
:
29
:
:
:
32
:
22
30
:
31
:
34
31
27
21
24
26
27
:
s
12
35
37
:
3$
3$
:
32
:
--
:
:
:
25
2$
27
:
26
:
36
32
31
:
:
:
3
:
22
26
27
:
26:
35::45
:
29
3
:
Asphalt impregnated
V2s
:
Original
b
:
----
9
:
--
:
--
:
:
:
:
12
:
L.
------
--:
:
:220
400:
:
12
D.
-----
:
:
:
:
:
------
------
:
:
:
:
:
:
:
:
:
:
-
:
-----
:
:
:
:
--
:
419
42$
:
326
:418
32$
:
40$
421
420
:
:
:
:
:
41$
:
--
o4
530
520
422
:
:
:
:
:
530
506
530
47$
432
:
--
:
:Ligbt
:?4edtum:
:
:Me&tum:
:Medium
:
------
:
:
:
:
:
------
:
:
:
Original:
:
:
:
:
23e
3
6
9
12
:
:
:
:Original:
:
3
:
:
h
:
9
:
:
12
!"An average of
"An
-:
average of
:
315
254
116
270
-----_
t tests for
5
41
265
175
196
179
:
:
:
:
:
:
:
:
:
:
-1182
:
:
532
s
:
------
:
:
194:
520
:
:
:
------
:
:
:
:
:
:
:
:.
33
:
--
529
501
513
567
503
:
:
s
:
:
-----
:
:
--
:
654
:
565
:
544
:
506
:
--
:
299
276
26$
:
:--:265;
:
34
34
:
Laminated with a proprietary polyvinyl resin adhesive
112e
23
36
:
:
:
:
:
602
626
:
:
51$
478
479
:
:
:
237
234
23$
:
:
:
258
276
:
:
--
624
606
602
592
--
476
44$
440
452
62$
594
614
60$
618
:
:
:
:
:
:
:
:
:
:
51$
507
492
475
444
:
:
:
--
Light
Light
Light
Light
--
:Light
Light
Light
:
:
:
:
:
:
:
Light:
:
--
25
2$
29
2$
-----_
17
:
2$
33
29
35
:
:
:
:
:
:
:
:
:
------
:
:
:
-1$
27
:
:
:
:
24
:
:
25
:
:
--
:
:
44
:
:
57
40
45
:
:
:
each board.
punctures for each of
1
or
2
boards.
-
! She
uninoculated control samples were incubated under similar condittone as the inoculated ones except for the addition of volatile fungicides.
2h. original strength figures apply to both.
-
-
Z
M 593], F
23
27
2$
24
33
52
69
68
71
49
.
Z M
L
D.
C
B.
A.
:
:
Test
:
:
I;
i.oee in tensile strength
Tested dry
Tested wet
:
:
I;
Loss in
Tested wet
;
!!!!
Percent
I
:
:
:
9
12
-3
12
:
k
I
!
:
72
1
5
:
:
:
39
;
:
:
3
29
:
:
:
:
:
:
:
;
:
:
1
3k
--
--
:
:
:
---
k
77
5
63
3
65
65
62
29
36
39
i6
-----
69
l2
59
73
I
:
:
:
:
:
;
:
:
:
:
:
:
:
:
2
d
58
67
3
20
23
15
7
-----
19
10
:
:
:
:
;
11
10
:
:
:
:
:
6
11
11
:
:
:
:
:
+3
3k
:
:
:
:
:
:
:
:
:
-----
:
5
:
:
:
;
b
5d
5
:
26
id3
10
+2
31
3d
13
20
27
+
3
9
23
2
Percent
:
:
:
:
:
:
:
;
:
:
:
:
:
:
;
:
7
50
13
32
21
10
:
:
:
:
:
:
:
:
:
:
'13
39
50
12
:
:
:
16
+5
12
:
:
:
:
:
li.
5
Percent
Control
--
1].
12
2
53
113
31
17
17
25
7
1].
lO
13
17
Percent
111
:
:
:
:
10
1k
:
:
:
I
12
:
:
I
9;
b
----:
:
:
:
----I
:
¡
I
----I
:
I
I
----:
:
I
:
16
8
5
+9
:
:
:
I
:
:
:
:
:
:
I
:
:
:
:
:
1
:
:
:
1
:
I
:
:
1
:
1
:
:
:
:
3
6
9
12
tregnate4
9
12
6
3
9
12
I
12
9
3
-----
211
11.7
113
32
-----
-----
:
I
:
:
:
:
:
:
:
I
I
:
:
I
I
I
1
I
I
-----
30
36
i4.
32
---
-
I
:
:
;
:
:
s
I
I
:
--1
-----
----
--
30
15
21
33
-----
---
---
:
s
I
:
:
;
1
:
I
:
:
I
:
:
I
:
----
--
10
6932
V3a
F
:
:
:
:
:
:
9
:
:12:
6
12
;
I
9
3
I
:
V2s:
-----
2k
39
72
35
I
:
:
1
:
:
-----
36
58
53
57
I
I
:
:
:
;
--
--
---
2
62
I
:
s
:
:
10:
18
--
----
15
15
13
k
:
:
:
:
:
:
:
:
:
:
:
;
12
7
Z
:
:
:
:
;
I
:
I
21
-----
-----
Leminated with a proprietary polyvinyl resin adhesive
V2a
Asphalt
V3e
V2i
Vis
k
111
1
:
:
1
:
s
1
:
1
:
1
:
:
:
:
g
:
:
:
:
:
:
:
+121+16:
+3.3
+9
0
20
21
111
+111.
.
33
1k
20
15
32
29
23
+3
1
1
+10
1
i
+1
16
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
+26
+16
10
6
+9
2
ill
15
16
41k
5
9
2
6
O
+1
+2
29
32
18
15
211
:
:
:
;
211
:
i
19
1
:
Laminated with urea-tormaldehyde-etarch-emule tried-asphalt adhesive
V3s
2
:
:
:
:
:
:
:
:
:
;
:
:
:
:
:
:
:
:
3.5
13
:
111.1
8
6
14
11
1
O
2
9
5
+9
+1.
+7
6
7
k
k
5
7
+11
;
:
11
+7
:
:
1
12
9
10
7
i
2
:
:
:
:
:
I
:
:
:
:
:
:
:
:
:
:
1
1
:
:
1
:
:
:
:
:
;
:
:
:
1k:
2
5
9
2
2
3
5
10
18
O
5
+k
+6
+7
+6
8
7
3
5
+k
+9
+5
+16
8
7
11
6
:
1
:
:
:
:
s
19:
3k
+5
1.
5
1
:
:
l4
:
12
:
:
li.
d
Percent
:
:
:
:
:
:
:
:
:
:
:
;
Control
;
---
---
--
25
28
29
28
---
--
--
29
32
35
30
-----
-----
-----
116
11.7
56
k9
35
33
32
32
--
----
2.7
21
25
62
Percent
I;
:
:
;
:
:
:
:
;
:
:
:
:
:
:
:
:
:
:
:
:
;
:
:
:
:
:
:
:
:
;
;
:
:
:
:
:
:
33
:
-----
28
33
29
35
-----
28
31
115
26
-----
-----
----
--
110
11
58
&l
311
32
29
2
-----
2
2d
2
Percent
:
:
:
:
Control
:
:
:
:
:
1
:
:
;
:
I
:
:
I
:
:
I
:
:
:
3k.
:
:
;
:
:
:
:
e
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
;
:
Gd
71
69
27
28
2k
33
36
3k
3k
33
35
37
38
38
2k
26
27
21
36
36
32
31
37
38
37
38
39
66
60
50
39
117
113
57
32
32
26
:
:
:
ko
kO
32
Percent
Control
:
:
:
;
:
¿45:
¿46
57
114
2k
25
18
27
26
25
28
27
31
32
311.
29
22
26
27
30
36
32
33
3k
32
33
:
311
:
:
2d
72
60
52
k
ill
111
ko
3d
33
32
26
33
3
31.
31.
23
Percent
:
:
:
:
:
:
:
:
:
:
;
:
:
:
:
:
:
:
:
:
Moisture oentent of wet boards
Tensile tests
:
Tested dry
.:
Bursting tests
--------------------------------------- -------------------
Laminated with urea-tormaldehyde-etarch treated with 0.Od percent eodiuim pentachiorophenate
V3o
I
6
9
3
6
V3e::
I
:
:
:
:
:
9-:
3
b
9
12
3
12
:
:
:
:
¡
:
:
:
V2e
Vie
55
Percent
Percent
:
Percent
Laminated with urea-formaldehyde-starch
;
Control
Control
:
bursting strength
board:period: -----------------------------------------------------------
Type of
Table 3.--Decreaee in teneile and bureting etrength of V-boarde eubjected to molding at 97 percent relative humidity
and go P. Baced upon strength lose in comparison to original boards.
Z M
E.
'b.
C.
B.
A.
:
:
:
:
;
:
Completely delaminated
5% delamination
Delaminated except for small
area at center
Delaminated to depth of
1/2 to l-1/2 inches from edges
:
:
:
:
:
:
¿l-5%
and 12 weeks'
:
:
:
edges
Cuter plies 50% delaminated
Inner plies delaminated along
delamination
:
:
:
60% delamination
No delamination
No delamination
15% delamination
No delamination
30% delamInation of
outer plies only
No delamination
67267 P
No delamination
No delamination
V3s
:
No delamination
V2s
Laminated with a proprietary polyvinyl resin adhesive
V2s
Asphalt impregnated
:
9O
Delaminated except for small
area at center
V2s
:
60% delamination of outer plies
only
Vls
V3s
exposure to molding at 97 percent relative humidity and
Completely delaminated
Completely delaminated
Completely delaminated
All plies delaminated except for
small area at center of each ply
:
:
:
Outer plies completely delaminated
Inner plies 7O delaminated
sodium pentachlorophenate
:
:
:
;
:
:
:
:
No delamination
No delamination
No delamination
Outer plies completely delaminated
Inner plies delaminated around edges
Completely delsainated
Outer plies completely delaminated
No delamination of inner plies
Laminated with urea-formaldehyde-starch-emulsified-asphalt adhesive
V3s
O.o%
delaminátion
50% delamination
90% delamInation
10% delamination
Laminated with urea-formaldehyde-starch treated with
V30
V3s
V2e
Vis
7
F.
:
:
:
:
:
:
:
:
:
:
No delamination
No delamination
No delamination
Outer plies completely delaminated
Inner plies 50% delaminated
Completely delaminated
50% delamination of outer plies
delamination
O% delamination
Completely delaminated
Completely delaminated
90% delamination
Delamination after 7 weeks
Delamination after 12 weeks
of---------------------------------------------------------- --------------------------------------------------------------------------Edges exposed
Edges sealed
Edges exposed
Edges sealed
Laminated with urea-formaldehyde-starch
board
Type
Table U-.--The delaminationì of commercial fiberboard samples after
Table 5.--Tensile strength, molding, delamination, and. moisture content of cornmerciai W-boards subjected to molding at 97 percent relative humidity
and 800
Type
Test
of
period
board:
:
;
:
:
:
Tensile strengthi
:Amount Delamination
Moisture
---------------------------of
content of
Tested wet
Tested dry
wet boards
mold-:
-------------- -------------Ing
-------------Inocu-: Con-2: Inocu-:Control: Iriocu-: Control:
Inocu-: Control
:
:
:
:
:
:
:
:
:
:
:
lated:
Weeks
trol-: lated:
:
:Lb.per:Lb.per:Lber:Lb.per
in.
:
in.
:
in.
:
in.
:
:
lated.:
:
:
Per- :Percent:
cent
:
:
Per- :Percent
cent
Laminated with urea-forrnaldehyd.e-starch
A.
W5c :Original:
:
3
:
:
G
:
:
9
:
:
12
:
:
W5s
-28
:
:
:
:
:
21
:
:
;
37
:
--
:
184
--
:
:49
:
:
;
:
:
96
83
:
207
41
;
:
:
180
176
168
:
__
;
210
:
:
:
43
45
373
:
393
:
:
:
:
33
:
:
:
96
:
17
:
:
:137
:
113
:
:
139
:
;
:Original:
3
6
9
:
:
:
:
-23
17
15
;
:
:
:
40
29
31
33
:
12
t
:
:
:
:
-93
73
58
:
13
:
16
t
t
;
:
:
:
135
126
141
jQ
:
42
t
t
56
79
t
W5s :Original:
3
t
6
:
9
12
.iAverage of
:
:
:
t
--
:
208
t
192
193
186
t
:
:
291
191
135
158
196
:
:
t
t
t
-331
326
305
354
t
t
t
t
348
344
345
314
351
39
:
41
:i-ay:
!rT :100
48
:
:
41
:
49
:
:
33
62
5?
49
t
Z?
:
25
..
:
-:
O
O
:
10
:ery
:
100
:
10
-21
24
25
-
:
--
:
Heavy:
:}Iea\y
:
-75
95
:Very
loo
heavy:
100
Very
heavy:
:
:
:
-O
:
5
:
10
:
92
20
t
t
:
t
resin
t
:
5
10
:evr:
:
:
:
:nvy:
;
:
O
46cVev;-:90:
:
52
:
-90
:H'avy
39
--
:kieavy:
68
--
:
:
iOO
100
29
:
Laminated with a proprietary polyvinyl
Very
:
:
95:
;
:
t
:Heay
-9O
;
:
12?
:
55:Heavy:
:
W6c
--
59
:
400
:
60:Heavy:
..-
:
:
31
:
:
452
:
:29: 8:177: 339:48:
:
12
39
32
:
:
9
54
36:l27: 170: 55:
23
:
3
G
:
22: 40:103;
;Original;
:
L
lated:
adhesive
t
16
27
32
t
27
-:Light
:Light
:Light
:
30
t
:
:
:
Light
:
t
:
:
:
-O
O
O
O
:
t
t
:
-O
O
O
O
4 tests for each board.
uninoculated. control samples were incubated under similar conditions as the
inoculated ones except for the addition of volatile fungicides. The original
strength figires apply to both,
For.Path.Spec.Pe1ease No. 29
Z
1.7
0.5
1.7
1.0
1.7
2.0
Furnish
Adhesive
Furnish
Adhesive
Furnish
Adhesive
:
:
:
:
:
:
12
3
7
5
:
:
:
:
:
:
:
:
:
l6
kl
-560
14.33
1495
1441
--
513
2437
515
--
526
Ll2
371
--
563
379
393
--
ll
-600
32
313
577
--
545
314
206
gin.
36
Lb. per
:
:
:
:
:
:
:
:
:
:
:
:
e
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
72
14.93
14.95
562
'i-SO
1496
502
142
14614
2452
1163
k2
92
72
27
2O
5l
507
5311
516
524
513
5O
5O
536
520
507
Il.9
-----
Lb. per
sg. in.
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
.
:
Bursting strengthi/
:
in.
per
O
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
530
531
246
502
516
14.62
14514
512
1495
2
--
535
502
72
51
562
515
550
--
532
1-6l
O
530
511
536
530
-----
Lb. per
sg. in.
--:1496
5314
527
--
146
1472
525
--
--
5124
553
--
I5
Ii-65
--
5X6
32
392
--
--
'402
511
--
O
550
560
--
432
1412
511
5o1
Lb.
sg.
:
Tested wet
Testad dry
----------------------------------------InocuInocu2/
ControlControl
lated
lated
:.
:
:
:
:
:
:
:
:
:
:
:
¡
:
:
:
:
:
:
:
:
:
:
:
:
:
punctures.
Original
12
3
7
Original
12
3
7
Original
l2
3
7
Original
12
3
7
Original
12
3
7
Original
12
3
7
Original
12
7
3
Original
!!!.!
period
Test
Light
--
molding
Of
Amount
:
:
:
:
.
.
.
:
-O
delam
inatton
moun
--
Light
Heavy
--
Very light
Very light
--
Medium
None
Light
--
Heavy
Heavy
Light
--
Heavy
Very heavy
Light
None
Very light
--
Medium
None
Light
--
:Light
:
:
:
:
:
:
:
:Light
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:Heavy
:
:
:
O
-O
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
-O
O
O
O
O
O
--
0
O
O
--
Slight
:
:
:
:
:
:
:
:
:
:
:
:
:
O
O
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
.
--
Medium
O
O
--
Slight
Heavy
O
--
:Slight
:
:
:
:Veryheavy:Slight
:Veryheavy;Heavy
:
:
:
:
.
:
:
:
6933
F
O° F.
:
:
:
:
:
:
:
:
:
;
:
:
:
:
:
:
:
:
:
:
:
;
:
:
:
:
:
:
:
33:
27
29
--
37
37
33
--
29
3
31
--
27
31
30
--
35
3
29
--
35
3il
23
--
23
37
33
--
3
35
2
21
Percent
:
29
23
22
2k
k
2
30
22
27
224
27
30
27
2
2
21
19
19
26
25
23
23
23
2
22
26
37
23
-----
Percent
wet specimen.
------------------InocuControl
lated
Moisture content
uninoculated control samples were incubated under similar conditions as the inoculated ones except for the
addition of volatile fungicides. The original strength figures apply to both.
.?J'The
M
:
:
:
:
:
:
1.7
0.0
:
Furnish
Adhesive
:
:
:
:
:
:
:
:
:
:
:
0.0
2.0
0.0
1.0
:
Furnish
Adhesive
Furnish
Adhesive
:
:
:
:
:
:
:
:
:
:
:
:
:
¡
0.0
0.5
0.0
0.0
:
;
:
Furnish
Adhesive
Furnish
Adhesive
Percent
:
:
:
:
:
:
:
:
:
:
;
:
;
:
:
:
Preservative
added
'Each figure is an average of
91
9
90
7
6
Sample
number
;
ing amounts of sodium pentachiorophenate and subjected to molding at 97 percent relative humtdity and
Table 6.--Burating strength, molding, delamination, and moisture content of experimental fiberboards treated with vary-
.
Z
M
.
.
Furnish
£dhösiv.
Adhe.Ive
.
12
6
9
12
3
b
9
Original
3
b
9
12
Original
12
9
3
b
Original
12
9
b
3
Original
.
3
Original
12
b
9
Original
Weeks
:
:
:
:
2.0
:
:
2.0
1.0
:
3
.
12
9
b
3
:
:
:
:
:
:
:
:
:
:
Te;t;d;et
:
:
:
:
:
:
:
1140
1O
l7
l6Jl
--
lL
:
:
:
:
:
:
:
:
--
152
127
ikk
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
:
:
:
:
:
:
:
;
:
:
;
--
132
12
1ko
135
137
l3
130
132
--
5
117
152
90
--
91
100
-l6
135
1193
95
107
--
119
127
93
95
--
in.
Lb. per
:
:
l2'
159
1k6
151
127
139
139
--
1%
173
------
132
137
1140
115
122
12'
129
125
1lZ
1119
122
139
1140
l7
l
129
-ll
95
112
132
9
1ko
1O
161
Lb. per
In.
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
-
Tensile strength!.'
:
220
207
232
2h42
--
232
200
208
210
--
225
--
1l
239
--
10
-22
21
215
129
1%
-229
196
l3
1%
220
232
--
139
l2
l4.O
173
--
l6
ll
229
195
--
Lb. per
in.
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
239
227
217
22
213
2Ul
232
220
227
--
225
---
23--
222
210
222
22
229
2O
201
193
190
21
22
217
196
217
2U.2
176
152
176
--
237
229
217
207
193
229
Lb. per
in.
--------------------- ------------------InocuInocuControl
Control'
lated
lated
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
tests.
Original
12
9
b
figure is an average of
:
:
:
:
:
:
:
:
¡
¡
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
:
Test
period
2.O:Originl:
2.O
0.5
2.0
0.0
2.0
0.0
0.0
1.0
0.0
0.5
0.0
0.0
:
:
f
:
:
:
:
Very ltght
--
Very light
Very light
Very light
Light
--
None
Very light
Very light
Very light
--
Very light
Tracs
Trac.
Tracs
--
Heavy
Heavy
Light
Heavy
--
Heavy
Light
Heavy
Heavy
--
Heavy
Light
Heavy
Heavy
--
Heavy
Very light
Heavy
Heavy
--
Amount of
molding
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
:
:
:
:
:
:
;
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
Very light
Very light
:
:Verylight:
:
;
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
;
:
:
:
,
Slight-
O
O
O
--
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
;
;
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
2
22
28
17
--
27
27
21L
17
--
--
2
2
19
20
-19
2
30
2
3
2
-21
23
-17
2k
36
32
32
26
-21
2
-2
26
30
31
Percent
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
:
;
:
;
:
:
:
:
:
:
:
:
;
:
:
:
:
:
:
plies only.
6935
F
19
16
20
29
2g
2
--
2
17
17
------
27
20
2I
26
1
19
21
30
2
17
2
26
i6
22
27
27
2Q
-21
32
26
17
Percent
Moisture content
øf wet specimen.
:-------------------InocuContl
latod
I:
51ight'1
$1ight',
Sltght.J
O
--
-O
O
O j,
Slight-'
O
,
S11ght',
Slight-'
-O
Slight
Medium
51ight'
-O .,
Heavy
O
Slight
O
--
Light
Medium
Light/
O
--
Light
Heavy
O
O
--
delamination
of
:
as the inoculated one, except for the
uninoculated control samples were incubated under similAr conditionsto both.
The original strength figures apply
addition of volatile fungicides.
-
Furnish
£dh..1v.
?urnt.h
Adhesive
Furnish
Adhesive
Furnish
Adhesive
Furnish
Adhesive
Furnish
Adhesive
Preservative
added
:Purni.h
:
;
:
:
s
:
:
:
:
:
z
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
:
:
:
At corners only.
10
102
-
100
9g
105
103
101
99
Sample
number
:
or experimental fiberboards treated with varyTable 7.--Teneile etrength, molding, delamination, and moisture content
at 97 percent relative humidity and d0 F.
Ing amounts of sodium pentachlorophenate and subjected to molding
/00
'VV
I
80
5c
VOt-STA RCH
80
60
tH
40
20
20
'oc
I00
80
80
'
__
-.1
20
tu
__ ________J
Vis UREA- FORM4
o
20
n
I
W6
RA-POR/i'ALDHVÛE-$7ARCH
Vid
8C
-DRV
60
V3S UEA-t'ORMALOEHVOESTARCH
40
/00
t.j
\::%\\ç,3i
£1R(A-;::MALOEHYOSTA ROH
_
6G
40
40
20
20
_-
WET
o
/00
80
r_z___i___j
I
- -
-
POL VVINVL
;'DRV
4C
20
2C
6
9
/2
"0
LENGTH 0F (XPOSIRE(WEE*'S)
I_
VP s PROPRIETARY POLYVINYL RESIN
n
3
3
6
9
FIGURE I. - - WET AND DRY TENSIL E STRENG 1W OF V- AND W- BOARDS EXPOSED TO
MOLDING AT 97 PERCENT RELATIVE HUMIDITY AND 80° F.
z
67475
-
---rn
60
40
-
VÇ
8G
60
0
__________
60
4c
80
,
\,'_----i-
40
o
-J
______ ______
,
60 r
60
'
______
/2
Figure 2.--Mold.ing and. delamination of commercial fiberboard.s
after 12 weeks' incubation at 97 percent relative
The numbered samples were
humidity and 80° P.
inoculated., while the samples numbered and lettered
were not inoculated.
No.
1.
Urea-formaldehyde-starch
Type Vis.
adhesive,
No.
5.
Type V2s. Urea-formaldehyde-starch
adhesive.
No,
6.
Urea-formaldehyde-starchType V2s.
asphalt emulsion adhesive.
No.
7.
Type V3s.
No.
11.
Type V2s. A proprietary polyvinyl resin
adhesive for filler and asphalt for
liners,
No.
12.
Typo V3s,
Asphalt for liners ureaformaldehyde-starch pius 0.08 percent
sodium pentachiorophenate for fillers.
No.
13.
Type V3s, A proprietary polyvinyl resin
adhesive for all plies.
No.
15.
Type Vis.
No,
16.
Type V3s.
Urea-formaldehyde-starch
adhesive.
Urea-formaldehyde-starchasphalt emulsion adhesive,
No. 17.
For.Path.Spec,Release
No.
Urea-formaldehyde-starch-asphalt-emulsion adhesive.
Type V2s.
29
Asphalt impregnated.
IA
S
'7A
/00
/00
80
80
60
60
40
40
20
FURNISH 00 PERCENT
ADHESIVE 0.0 PERCENT
o
20
FURNISH 2.0 PERCENT
ADHESI VE 0.0 PERCENT
o
/00
/00
80
80
60
40
20
FURNISH 0.0 PERCEN T
ADHESI VE 0.3 PERcENr
20
o
FURNISH 2.0 PERCENT
ADHESIVE 0.5 PERCENT
o
/00
'VC,
60
60
60
60
40
40
20
FURNISH 0.0 PERCENT
ADHESIVE IO PERCENT
20
FURNISH 2.0 PERCENT
ADHESIVE 1.0 PERCENT
o
/00
/00
80
SO
60
60
40
40
20
FURNISH 0.0 PERCEN r
ADHESI VE 2.0 PERCENT
-
20
O
n
3
o
6
9
IP
0
3
6
FURNISH 2.0 PERCENT
ADHESIVE 2.0 PERCEN r
9
LENGTH 0F EXPOSURE (WEEKS)
Figure 3.--Tensile strength of' reclaimed fiberboard treated with sodium
pentachlorophenate and subjected to molding at 97 percent relative
humidity and 800 F.
Z
M
57475
T
/2
Figure 4.---Molding and. delamination of experimental fiberboards, with and without sodium pentach1oropaenate
in the furnish and adhesive, after 12 weekst incubation at 9? percent relative humidity and 80° F.
No.
98.
2.0 percent preservative in furnish,
none in adhesive.
No.
99.
No preservative in furnish or in adhesive.
No.
100.
2.0 percent preservative in furnish, 0.5
percent in adhesive.
No.
101.
No preservative in furnish, 0.5 percent
in adhesive.
No.
102.
2.0 percent preservative in furnish, 1.0
percent in adhesive.
No.
103.
No preservative in furnish,
in adhesive.
No.
104.
2.0 percent preservative in furnish,
2.0 percent in adhesive.
No.
105.
No preservative in furnish, 2.0 percent
iz adhesive.
For.Path.Spec.Release
N.
29
1.0 percent
Z M 70355 ?