Armored 
Medical Research Laboratory 
Fort Knox, Kentucky 
Report 
On 
PROJECT NO. 27 - TEST OF COMPOUNDS - FIRE RESISTING, FOR 
FIELD TREATMENT OF CLOTHING - OQMG-253 
Project No. 2? 
13 Karch 19*4 ARMY GROUND FCPCZS 
MEDICAL RESEARCH LABORATORY 
fon Knox, Kentucky 
Project Noo 2? 
File i+0 0 o 1X2 
13 March 1944 
FIRE RESISTING COMPOUNDS FOR CLOTHING 
1. PROJECT: Test of Compounds - Fire Resisting, for Field Treatment 
of Clothing - OqjiG -253. 
a° Authority - Letter, Commanding General, Headquarters Array 
Ground Forces, Army War College, Washington, Do C0, GNRQT-6/68999, January 
23, 1944. 
b. Purpose - The purposes of the test, as defined by the 0,QoM 
were: 
(l) Evaluation of the ease of field application of two flame 
retardant compounds to standard issue clothing. 
C2) Evaluation of the qualities of treated garments (under 
anticipated extremes of humidity and temperature, when applicable) to 
include; 
. (a) Comforto 
(b) Irritation or dermatological reactions. 
(c) Undue failures of treated garments compared to 
untreated garments.* 
(d) Does perspiration or light rain leach out the treat- 
ment with such rapidity as to make it ineffective? 
(3) Evaluation of the amount of relative protection treatment 
provides when garment is dry; when wet with perspiration or rain. 
(4) Evaluation of the life of the treatment under field 
conditions. ' 
2o DISCUSSION; 
ac Verbal and written reports from combat theaters indicate that 
burns are very common. They may be caused by ammunition fires, fuels, lubri- 
cants, flame throwers, incendiary bombs and shells and a variety of other 
materialso Clothing affords a very real protection against many of these 
sources of burns provided the soldier is not in contact with the heat source 
too long and provided his clothing does not ignite0 Too frequently a man may receive serious burns from his own clothing after he has extricated 
himself from the original source of the fire0 For that reason, a fire 
retardant in clothing would be a very real advantage0 
b0 Two compounds, "Flarae-out" - Treasdale and nFire Retardant 
CM” - Dupont, made commercially for similar purposes, were supplied for 
test as possible temporary solutions to tne problem. 
c. Details of the procedure used and the results of the various 
tests will be found in Appendix A. 
3o CONCLUSIONS: 
a. Both compounds are easily employed in the field provided 
the. garments can be dried in a reasonable length of time (from 2 to 3 
hours)o This may be difficult or impossible in damp climates. 
b0 Within the limited ranges of these tests, neither compound 
appeared to affect materially the life of the garmenta (Extended wear 
and tear tests were not done.)* 
c„ Both compounds leach out very quickly in moderate rain or 
with copious sweating. This renders the "Flame-out” - Treasdale impract- 
ical because of loss of effectiveness. In the case of "Fire Retardant 
CM" however, such a small quantity is actually needed to produce results 
that the rapid leaching does not destroy the usefulness of the treatment. 
do Comfort, and the heat load imposed by the clothing are not 
appreciably affected by impregnation with either compound as carried 
out in the field. (The weight of clothing is increased by approximately 
5*0 
e0 No dermatological reactions were noted with either compound 
with concentrations of flame retardant in the cloth not in excess of 7% 
by weighto Higher concentrations were not triedo 
f. The charring-time and ignition (glow) time of the impregnated 
as compared with the untreated fabric at 50O°C is not prolonged by either 
compound. 
g. The duration-of after-glow and burning when the heat source 
is removed is materially reduced by both compounds. Unimpregnated HBT 
will continue to burn until completely incinerated. "Flame-out" stops 
after-glow when a small hole has developed. "Fire Retardant CM" stops 
after-glow as soon as the heat source is removed. In equal concentrations 
it is far superior to "Flame-out". 
* The N.D.R.C. research group at Columbia University reports that repeated 
impregnation will shorten the life of the garment. ho Protection against burns was measured only with garments im- 
pregnated with "Fire Retardant CM" because "Flame-out" was found to be im- 
practicalo Clothing treated with the "Fire Retardant CM" as compared with 
the unimpregnated fabric, gives no increased protection against a bum on 
human skin from hot air; in fact, the treatment appeared to increase 
slightly the severity of a burn for constant temperature and time of ex- 
posure o This compound does not increase the protection against burns 
afforded by wet garments. Its great, very real, and only advantage there- 
fore, is that it instantly stops burning in the garment when the heat 
source is removed (stops after-glow). 
i. HBT fatigue clothing impregnated with "Flame Retardant CM" 
will stand one vigorous hand washing in cold water, without soap, before ' 
re-impregnation is necessary. 
jo A solution of retardant (10jt by weight) in warm or cold water 
is optimal for field impregnation. Twenty gallons of such a solution will 
impregnate about fatigue uniforms. 
4. RECOMMENDATIONS: 
a. That field impregnation of fatigue uniforms with "Fire Re- 
tardant CM" be considered an effective temporary measure for stopping 
fires. 
b. "Fire Retardant CM" or other agent of equally desirable 
characteristics be issued to the following men in the combat zones of 
all theaters, basis of issue to be 25 pounds per tank company or equivalent 
(1) Tank and other vehicle crews. 
(2) Gasoline and ammunition handlers (1st echelon). 
(3) Personnel handling or using incendiary agents including 
flame throwers, 
(4) Other personnel designated by unit commanders because 
of exposure to fire hazards. 
c. Instructions be issued for the application of the retardant. 
A proposed draft is attached (Appendix B). 
d. Development of more effective and permanent methods of fire- 
proofing clothing be continued. Comments and recommendations of the Amo red Medical Research Laboratory 
concurred with by Colonel Harold G. Holt, Acting G/S Headquarters Armored 
Center, except as fellows: 
1. That the burden of impregnating clothing should not be placed on the 
company nor any other element of the Division in combat because of: 
a. Insufficient personnel to do the Job. 
b. Drying facilities not available. 
2. It is recommended that the impregnating agent be issued to the theatre 
commander in sufficient quantities to process a depot stock, the amount to be 
detemined by him. It is the opinion of this headquarters that impregnating 
clothing can be facilitated by means available to the theatre commander, such as 
laundry companies. 
3. That immediate steps be taken to prepare clothing in the United Stales 
for shipment as requested by the theatre commander. 
Prepared by: 
Major W, F. Ashe, M.C, 
Capt. W, B. Bean, 11.C, 
APPROVED 
WILLARD LACHLL 
Colonel, Ledical Corps 
Commanding 
3 Incl. 
#1 - Appendix A - Full Data 
#2 - Appendix B - Procedure for use 
#3 - Chart - Schematic Drawing of Burning Apparatus APPENDIX A 
1. Material tested - Two flame retardant materials were supplied 
for field test on suits, working, two piece, Herringbone Twill. They 
are "Flame-out" - Treasdale, henceforth indicated as retardant No. 1 and 
"Fire Retardant CM" - Dupont, indicated as retardant No. 2, 
2. Application - Twenty pounds of each agent were dissolved in 20 
gallons of cold water in a 30 gallon can. Sixteen suits of fatigues, 
previously dried at 110°F and 20S& relative humidity and weighed (within 
1 gram), were soaked for 20 minutes each (16 suits in Solution 1, and 16 
in solution 2)0 Each was hand wrung by one man, thoroughly dried and 
re-weighed under the above conditions. The difference in weights represents 
the amount of impregnating material taken up0 The average for No0 1 was 
5% of the total dry weight and for No. 2, 6%a Field application is feas- 
ible and easy and requires only a little sun for drying. In deep jungle, 
drying would not be possible. Where clothing is always wet, impregnation 
is probably unnecessary because it does not increase protection, as will 
be shown later. 
3o Control suits - Eight control suits were dried and weighed in a 
similar fashion,, These were used in both the heat load and leaching out 
experimentse When men sweat profusely, they add salt and some detritus 
to the garmentso The average weight gain of control garments, under 
identical useage, measures this added factor* Consequently, the control 
suit weight gain was subtracted from suit weight losses in the leaching- 
out-by-sweat experiments. This correction was not made in the rain ex- 
periment because the rain was very cold and the closure short* There 
was no sweating during the rain test. 
4o Test,s - The procedure and data of the several individual tests 
follow: 
a. Leaching out 
(l) Dip impregnated suit in water (60°F) for 30 seconds. 
Hang up and allow to drip dry. This procedure may be considered as roughly 
equivalent to falling into a river or lake. The garments were weighed (dry) 
before and after the test to determine the amount of agent lost. 
Retardant 
Impregnate • Wgt. 
Before, grams 
Impregnate 
Lost, grans 
Percent 
lost 
Noo 1 
S5 
62o8 
74 
82 
61,5 
75 
80 
56,8 
71 
Average 8203 
60,4 
73 Retardant 
- Continu 
Impregnate Wgto 
Before, grams 
sd - 
Impregnate 
o Lost, grams 
Percent 
Lost 
No0 2 
76 
36.8 
43.3 
69 
38.8 
56 02 
64 
37o9 
59.2 
71 
36.1 
50.8 
Average 70 
37 ok 
53.6 
(2) Men wore suits during a inarch of 6 miles at 3 mph, with 
20 pound pack. Temperature 100°F, Relative humidity 50$o No sunshine. 
Sweat loss rate 740 c.c./hr. Such conditions may be encountered in any 
hot southern climate on a cloudy day. The garments were weighed (dry) be- 
fore and after use to determine the amount of impregnating material leached 
by sweat. 
Retardant 
Impregnate Wgt. 
Impregnate 
Percent 
Before, grams 
Lost, grams 
Lost 
No0 1 
61 
36 
59oO 
63 
40 
63.5 
61 
38 
62.3 
86 
55 
64o0 
Average 68 
42 
62 o 2 
No. 2 
101 
49 '* 
39.6 
85 
37 
41o3 
88 
51 
58.0 
Average 91 
44»2 
45o9 
(3) Men wore suits during a march of 6 miles at 3 mph with 
20 pound pack. Temperature 90°F, relative humidity 95%0 No sun. Sweat 
loss rate 1176 c.Co/hr, The condition is as severe a jungle environment 
as will be encountered anywhere. The sweat loss is great. Again loss of 
impregnate by sweat was measured. 
Retardant 
Impregnat e Wgt. 
Impregnate 
Percent 
Before, grams 
Lost, grams 
Lost 
No. 1 
68 
42 
61 
82 
58 
70o7 
79 
22 
27 o 8 
75 
46 
61.3 . 
Average 76 
42 
57.4 
No. 2 
50 
53 
108 
88 
46 
52.3 
86 
53 
6l06 
85 
32 
. 37.6. . . 
Average 77 
4?r 
63.1 (4) Walk 30 minutes in rain. Total precipitation during 
walk, 1/4 inch. Temperature 46°F, 
Retardant 
Impregnate Wgt0 
Impregnate 
Percent 
Before, grams 
Lost, grams 
Lost 
No. 1 
70 
65 
92.8 
65 
50 
79.5 
74 
51 
69.0 
_ 63 
50 
77°0 
Average 68 
54 
79.6 
No. 2 
79 
75 
95.0 
73 
75 
102 o0 
98 
74 
75o5 
Average 83 
75 
90c 8 
b0 Measurements of heat load - Any garment imposes a certain 
additional heat load upon man working in a hot environment0 In order to 
determine whether impregnation appreciably increases the heat load due 
to fatigue uniforms, men were subjected to a standard work procedure in 
a constant environment with both impregnated and unirapregnated garments, 
Heat load was measures in terms of sweat loss per hour of work. Climate: 
Temperature 100°F, 50% relative humidity. 
Clothing 
Sweat Loss 
Noo Suit 
60S c.c./hr. 
Fatigues (untreated) 
771 c.c./hr. 
Fatigues Impreg. No, 1 , 
741 CoCo/hr, 
Fatigues Impreg. No, 2 
656 CoC./hr, 
Each value is the average of results obtained with 4 thoroughly 
acclimatized men. The same men performed identical work in each suit. The 
differences between the control and the two test suits are not significant. 
Co Burning characteristics 
(1) Normal and impregnated garments were cut into strips 2” 
x 3”o Each was held in front of a 1" diameter hole through which was coming 
a stream of air (6.5 liters per minute) at 500°C. The air stream was heated 
in a metal coil. The outlet orifice was 3/6" in diameter. The air stream 
traveled free for 1/V’ before impinging upon the burn target. Temperatures 
were measured by thermocouple at the face of the burn targeto See Chart 10 
Time was recorded as follows; 
(a) To produce charring on side away from heat. 
(b) To produce glow. 
(c) Duration of glow (after-glow) in room air with 
no additional heat0 (2) Results are presented below* 
Charring time in Seconds 
Retardant 
None 
No. 1 
No. 2 
3.27 
3.70 
2.60 
2.78 
3.52 
' 
3.00 
3o00 
3.25 
2.85 
3.10 
3.20 
3.00 
Glow time in Seconds 
Retardant 
None 
Ho. 1 
No. 2 
5*4 
4o05 
5o0 
5.13 
4oO 
5.1 
5d5 ' 
4c35 
5.1 
4o97 
4o32 
5o25 
Duration of glow (after glow) in seconds; 
heat source removed 
Retardant 
None 
No. 1 
No, 2 
until all of * 
66 
5»0 
cloth was de- 
96 
4o0 
stroyed, about 
54 
4*0 
k minutes 
60 
4o5 
Remaining protection after 605t impregnate leached 
out by sweat; time in seconds 
Retardant 
No. X 
No. 2 
Glow Time 
Duration Glow 
Glow Time 
Duration Glow 
3.S 
120 
5o4 
5o0 
3c 4 
180 ' 
5.1 
4o6 
Remaining protection after leached 
out; time in seconds 
Retardant 
No. 1 
No. 2 
✓ 
Glow Time 
Duration Glow 
Glow Time 
Duration Glow 
4.1 
252 
4o7 
3o0 
3o9 
Cloth destroyed 
4«9 
5o0 
3.9 
Cloth destroyed 
5oO 
4o0 Relation between quantity of Retardant No, 2 in 
fabric and protective effect 
Wgt. Cloth 
Before 
After 
e 
Diff. 
% Impreg. 
in Cloth 
Seconds 
Char. 
Time 
Glow 
Time 
Duration 
After Glow 
1. 
1.600 gm 
2.090 gm 
.510 gm 
24.456 
No Data 
6,2 Sec. 
1.0 Sec. 
2. 
1.558 
1.990 
.432 
21.7 
3.0 Sec. 
7.1 
1.0 
3. 
1.522 
1.816 
.294 
16.2 
2.0 
5.4 
2.0 
4. 
1.535 
1.768 
.233 
13.2 
1.5 
4.4 
1.6 
5. 
1.522 
1.706 
.184 
10.8 
2.0 
4.6 
2.0 
6, 
1.524 
1.6a 
.117 
7.1 
1.8 
4.5 
2.5 
7. 
1.566 
1.627 
.061 
3.7 
2.0 
4o9 
2.0 
e. 
1.602 
1.616 
,064 
3.a 
2.1 
4.5 
1.8 
9. 
1.434 
1.455 
.021 
1.4 
2.2 
5.0 
1.5 
10. 
1.467 
1.486 
.019 
1.3 
2*4 
*•5 
1.5 
11. 
1.354 
1.359 
.005 
.4 
2.2 
5.0 
1.9 
12 o 
1.327 
1.331 
.004 
.3 
2.2 
5.1 
1.5 
13. 
1.2550 
1.2565 
.0015 
.12 
2.4 
4.8 
1,6 
14. 
1.2121 
1.2134 
.0013 
.11 
2.2 
5.7 
1.6 
15. 
1.3446 
1.3451 
.0005 
.04- 
2.6 
6,0 
Incinerated 
16. 
• 1.3221 
1.3225 
.0004 
.03 
2.8 
5.6 
Incinerated 
17. 
Control 
(no impreg.) 
0o00 
3.0 
5.0 
Incinerated 
18. 
Control 
(no impreg.) 
0.00 
2.8 
5.1 
Incinerated 
Average T. 510° C 
Air 6.5 L/min. 
Only one-tenth of one percent (0,1%) of retardant No, 2 
by weight is needed in the garment to produce the desired effect (Stop 
after-glow). Garments originally impregnated by the above described field 
technique contain approximately 5% by weight. After losing 60% of the 
impregnate as result of leaching by either rain or sweat, the garment 
still contains 2% by weight, more than adequate protection. Even after 
losing 95% of the retardant when washed for 20 minutes in cold water 
without soap, the garment still contains approximately 0,25% and is pro- 
tective, Therefore, the margin of safety after a single impregnation 
is relatively great, though protection is only temporary. Repeated 
wetting, washing in cold water with soap or in a G.I, laundry will re- 
move all of the impregnating agent. 
d. Protection against burns. 
(l) Impregnated and non-irapregnated cloth were placed on 
the forearm and the length of time was recorded to produce a definite 
bum by a hot air stream. (Temperature - 500°C, Air flow 6.5 L/^in.) No Covering 
Untreated Fabric 
Fabric treated with Retardant 
No. 2 
0,25 Sec, 2nd 
Degree burn 1,0 
Cm diameter 
Dry 
2.$ Sec, 2nd Degree 
burn 0.8 Cm diameter 
201 Sec. 2nd Degree 
burn 1,2 Cm diameter 
Wet 
2.9 Sec. 1st Degree 
scald 4.0 Cm diameter 
2,6 Sec, 1st Degree 
scald 2,0 Cm diameter 
2.6 Sec, 1st Degree 
scald 5*5 Cm in diameter 
®° Comfort and skin irritation. 
(1) Suits were worn by eight men for three weeks outside 
in winter cold (25°F), in wet cold rainy weather (46°F) by eight men for 
one day, in a simulated hot southern climate (100°F, relative humidity 
5056, with and without simulated sun) by eight men for three days, and 
under simulated severe jungle conditions (90°F, relative humidity 95$) 
by eight men for three days). No discomfort was noted. There was no 
apparent change in the texture of the cloth. No skin reactions occurred 
(men wore nothing under these garments during skin tests). Patch tests 
were done on fifty (50) men with each agent (5$ of patch by weight was 
impregnate patches consisted of squares of impregnated cloth 1/2" x 1/2" 
applied to the arm by adhesive with an intervening layer of celophane. 
Area examined at 24 and 48 hours). No reactions were seen. 
f. Durability of impregnated do tiling. 
The impregnated garments were worn by men on regular duty 
for two weeks and showed no apparent weakness due to impragnation. This 
does not represent an adequate test* See footnote of report, page 2. 
This office Is informed that the O.Q.M.G. is doing extended wear and tear 
tests. 
5o Summary of results; 
a. Dipping suits in water or wading through streams can be ex- 
pected to leach out sufficient quantities of No, 1 (Flame-out - Treasdale) 
to make it ineffective. The same procedure with suits impregnated with 
No. 2 (Fire Retardant CM - Dupont) causes from 45$ to 70$ leaching, but 
not enough to lose effectiveness. 
b. Similar results are produced by heavy sweating (1000 c.c. 
per hour) and by soaking in moderate rain. 
• c. The heat load imposed by the garment is not significantly 
increased by impregnation with either agent if the impregnate does not 
exceed 7$ of the total weight of the garment. do The burning characteristics of the cloth while in contact 
with a heat source are not appreciably altered by the treatment nor 
does the treatment increase the protection as compared with that afforded 
by the untreated garment against skin burns from hot air while in contact 
with the heat source. 
e. "Fire Retardant Gif’ Dupont stops flame and after-glow as 
soon as the heat source is removed and thereby affords very real pro- 
tection against additional burns from fire spreading through the garment. 
f. Impregnation in the field is practical and valuable as an 
expediency and temporary measure. Twenty-five pounds of "Fire Retardant 
CM" Dupont in 25 gallons of water will impregnate approximately 100 fatigue 
uniforms• 
g. The texture and comfort of the suit are not appreciably 
altered by the treatment and skin reactions are not to be expected. 
h0 A more permanent impregnating procedure is desirable, and 
additional studies of the effects of impregnation upon the life of the 
fabric are neededc APPENDIX B 
Instructions for impregnating clothing with "Fire Retardant CM". 
lo "Fire Retardant CM" is a chemical agent which will stop fires 
and afterglow in clothing. 
2. Its action is only temporary because it is rapidly removed by 
repeated wetting or washing. 
3. Because of its temporary effectiveness and because it may shorten 
the life of garments, it should be used only where men are going into 
action and only for those exposed to fire hazards; particularly; 
a. Tank crews 
b. Personnel handling or using incendiary agents including 
flame throwers- 
Co Personnel handling gasoline and ammunition (1st echelon 
supply) 
d. Other personnel designated by unit commanders because 
of exposure to fire hazards 
4. To impregnate clothing with this agent, dissolve twenty-five 
pounds (25 lbs.) of "Fire Retardant CM" in twenty-five gallons (25 gal) 
of water in container, 33 gallon; galvanized iron. Soak garments in this 
solution for 20 minutes (Note: If uniforms are new and unlaundered, 40 
minutes will be required to assure saturation). Wring by hand (do not 
use mechanical wringer) and hang on line to dry. This solution will 
impregnate approximately one hundred (100) suits, two piece (or one piece) 
herringbone twill or equivalent. Not more than six (6) suits are to be 
placed in the solution at any one time.* 
5. Re-impregnation is required every time clothing is washed. 
* Where small units are widely dispersed, issue on an individual basis 
may be considered. One quarter pound (1/4 lb) in two quarts of water 
will impregnate one suit. Procedure is the same except that suits are 
not to be wrung out. CHART 1 
SCHEMATIC DRAWING OF BURNING APPARATUS 
CHART I