Armored Force 
Medical Research Laboratory 
Fop*t Krsiox, Kentucky 
Report On 
TEST OF ELECTRICALLY HEATED GLOVES 
Project No. 1-21 
March 20, 1%3 ARMORED FORCE MEDICAL RESEARCH LABORATORY 
Fort Knox, Kentucky 
Project No* 1-21 
File No. 727-122 
March 20,'1943 
TEST OF ELECTRICALLY HEATED GLOVES 
1. PROJECT: 1-21, Test of Electrically Heated Gloves (Hand Warmers).. 
a, Authority - Letter G-4, Headquarters Armored Force, Fort Knox, 
Kentucky, File X422.4 (jNOHD, dated March 14, 1943* 
b, Purpose - To determine whether there is a requirement in the 
Armored Force for the subject hand warmers (electrically heated gloves). 
2. DISCUSSION: 
Radio operators and maintenance men have the greatest need 
for adequate hand protection since their duties necessitate not only a 
high degree of finger dexterity, but also involve frequent and extended 
contact with cold objects of high heat conductivity. Moreover, they 
engage in only moderate physical activity and are thus denied the benefit 
of the greater body heat production and blood circulation which come with 
physical exercise. For these reasons, radio operators were selected as 
the principal test subjects in the study of the electrically heated gloves 
In order to simulate actual conditions of operation, radios were placed in 
an M2 personnel carrier and the operators required to perform their usual 
duties while seated in the vehicle during each test period, . The degree 
of protection afforded by the electrically heated gloves was compared with 
that given by standard winter mittens and certain other combinations at a 
temperature of -30°F and 25 mph wind velocity. The performance of the 
several types of hand protectors was observed^Vrith' both the subjects 
adequately and inadequately clothed. Details of the test procedure and 
discussion of results are given in the Appendix. 
3, CONCLUSIONS: 1 ' 
a. The electrically heated gloves were slightly superior to the 
other typess of gloves when conditions were such that the feet were not 
painfully cold. 
b. The electrically heated gloves were definitely superior to 
the other""types of hand protection when the subjects* feet were painfully 
cold. In other words, the protective effect of the heated gloves became 
more apparent under more severe test conditions. 
1 £. None of the glove combinations maintained the warmth of the 
hands while in contact with cold radio parts. The hands warmed most 
rapidly after cessation of such contact, however, when the electrically 
heated gloves were worn, 
d, The electrically heated gloves retain their flexibility at 
low temperatures and allow manipulation of radio controls to be carried 
out with ease, 
£, is no requirement for rheostat or switch. 
f. The electrically heated glove, in its present experimental 
form, has certain disadvantages which may be remedied, 
4. RECOMMENDATIONS: 
a. The electrically heated gloves as submitted for test be 
considered unsatisfactory for us© by the Armored Force, 
b. Suitable modifications as recommended in paragraph 4, Appendix 
"A11, be made by the manufacturers. ' 
£, The modified gloves be tested both in the field and the labora- 
tory prior to a final- decision relative to their adoption. 
Submitted by? 
Lt, Steven M, Horvath, Sn, C, 
Lt, Arthur Freedman, M.C. 
APPROVED^ 
WILLARD MACHLE, 
Lieut, Col,, Medical Corps, 
Commanding, 
2 Incls: 
//I - Authority for Project. 
#2 - Appendix "An w/aketch. 
2 HEADQUARTERS ARMORED FORCE 
Office of the Commanding General 
Fort Knox, Kentucky 
AFB P-362 
X 422.4 GNOHD 
March 14, 1943. 
SUBJECT: Hand Warmers. 
TO : Commanding Officer, Armored Force Medical Research Laboratory, 
Fort Knox, Kentucky, 
Confirming telephone instructions of March 1, 1943» from Major 
Thornbury to Lieutenant Colonel Machle, the Armored Force Medical Research 
Laboratory, is authorised to conduct test of Hand Warmers and submit report 
to this Headquarters. It was agreed between Major Thornbury and Lieutenant 
Colonel Machle that the report will be rendered March 15# 1943. 
By command of Lieutenant General DEVERS: 
/a/ C. M. Wells 
C. M. WELLS, 
Lieut. Colonel, A.- G. D., 
Assistant Adjutant General APPENDIX 
1, Test Procedures 
a. Tests were conducted at -30°F and 25 mph wind velocity. The 
seven subjects, five of whom were radio operators, sat in an M2 personnel 
carrier and performed the tasks assigned to them for a period of two hours 
during each test. The radio operators performed their usual duties, while 
the other two men wrote or manipulated the machine gun or steering wheel, 
b. Several glove combinations were tested for comparison with the 
electrically heated glove, as shown in Table I. • 
TABLE I 
COMBINATIONS OF HAND PROTECTION TESTED 
No. 1 - Glove, Heated; Glove, insert electrically wired and glove outer, 
leather; connected. 
No. 2 - Same as No. 1 except glove not plugged to battery. 
No. 3 - Ski Assembly; Mittens, shell, trigger finger; and mittens insert, 
trigger finger, wool O.D. 
No. A - Glove, work, leather, lined. 
No, 5 - Mittens, Fur; and Mitten, insert, trigger finger, wool O.D. 
No, 6 - Mittens, Fur; and glove insert, rayon (Canadian). 
No, 7 - RCAF Combination;' mitten shell, leather, and mitten insert, 
trigger finger, wool, and glove insert, rayon. 
£, Two different types of hand protection were compared on a 
single subject who wore one type on one hand and the second on the other. 
This procedure has been found to be necessary for quantitative evaluation 
since individuals vary so much in response to cold from one exposure 
period to another. Individual differences were further reduced by 
alternating the test periods so that a morning experiment on one day was, 
in essence, repeated on the succeeding afternoon. 
d. Two sets of experiments were conducted, one with the men 
adequately clothed for exposure to -30°F and 25 mph wind velocity, and the 
second with the subjects not fully protected so that they suffered general 
body discomfort. The combination of clothing worn in the two sets of 
experiments are listed in Table II; 
1 TABLE II 
A, "Adequate" Protection 
Suit, Arctic, six piece 
or (Suit, wool shearling, experimental 
(Parka, fur trimmed 
Kukluks 
or 
Shoe, Felt, Canadian 
Socks, Arctic 
Socks, wool, medium 
Socks, wool, light 
innersole, burlap 
B, " Inadequate" Protection 
Jacket, Combat, Winter 
Trousers, Combat, Winter 
Helmet, Combat, Winter 
Shirt, wool, O.D. 
Trousers, wool, O.D, 
Overshoes, Arctic, 
4-buckle 
Socks, Arctic 
Socks, wool, medium 
insoles, felt, or 
burlap 
The men dressed in an adjacent room and entered the cold room quickly 
to minimize sweating. 
e, Observations: Rectal temperatures were obtained before and 
after each test period. Subjective symptoms of the subjects and particular- 
ly their evaluation of one type of hand protection against another, were 
recorded at frequent intervals during each test. The current consumption 
of the electrically heated gloves was recorded. 
2, Results -. 
g., The effectiveness of the protection afforded by a given type 
of hand covering depends only part upon the hand covering itself. The 
blood or body temperature and the rate of blood flow to the extremities 
are important factors. These are influenced by individual differences in 
circulation, the amount of physical activity and the adequacy of the 
clothing. Because of these, hand protection which is adequate when the 
wearer is generally comfortable may not be so when he is wearing inadequate 
clothing and is generally cold. Accordingly the effectiveness of the 
gloves was evaluated with the subjects under both conditions. 
b. With adequate clothing. Results, with different combinations 
of hand protection, are compared In Table III on a basis of equal foot- 
cooling since in all cases, the trunk never became cold in these tests. 
The superiority of the electrically heated glove over the other types 
of hand protection is strikingly demonstrated by the comparative results 
when the feet were painfully cold. Thus, in one-half of the tests with 
the heated glove, the wearer reported his hand to be "cool" or "warm”, 
whereas, with all other glove combinations, the hand was "uncomfortably 
cool” or worse—the majority falling in the category of "cold with slight 
pain." The superiority of the heated glove was not as striking when the 
feet were not painfully cold, although no other combination gave protection 
better than "uncomfortably cool", whereas, the heated glove was reported 
better than this in ten of fourteen tests. 
2 Body comfortable; 
feet not painfully cold 
Body comfortable; 
feet painfully cold 
HAND SYMPTOMS 4 
No. of men wear-- 
ing each glove 
• 
HAND SYMPTOMS + 
No. of men wear- 
ing each glove 
Glove Combinations J 
Cool 
Uncomfortably 
Cool 
Cold 
Gold with 
slight pain 
Cold with 
severe pain 
Numb 
Warm 
Cool 
Uncomfortably 
Cool 
i Cold 
' Cold Tilth 
slight pain 
Cold with 
severe pain 
Numb 
Glove, Heated 6 
h 
h 
6 
3 
3 
h 
2 
5 • . 
Glove, Heated, not connec- 
ted 
3 
10 
2 
• 
t 
h 
h 
3 
Ski Trooper Assembly* 
1 
1 
3 
h 
2 
3 
RCAF Assembly, small 
1 
1 
2 
2 
1 
2 
2 
Mitten,Fur,with mitten, wool 
O.Do Liner 
0 
1 
2 
2 
Mitten, wool, 0oD. 
1 
1 
2 
2 
2 
Qlove,Leather,Wool,Lined 
2 
1 
0 
* Consisting of mittens, wool, trigger finger, and mittens, shell, trigger finger 
f Each figure represents the responses of one hand in a single experimental period. 
TABLE III 
HAND COOLING WITH EACH TYPE OF GLOVE 
(Clothing Adequate - 2 hr, exposure to -30°F., 25 MPH wind) c, With inadequate clothing. Experiments with inadequate 
clothing had to be terminated before definite conclusions with respect 
to relative hand protection could be drawn* The limited evidence which 
was obtained, however, indicated that the hands remained warmest when 
the electrically heated gloves were worn. 
di Hand protection during and following contact with cold objects. 
None of tYie various types of gloves was effective in preventing immediate 
chilling of the fingers and palms when handling microphones, writing notes 
or manipulating radio controls. After cessation of these activities, 
however, the electrically heated glove warmed the hand rapidly with complete 
restoration of comfort. With the others, warming was much slower and, in 
many instances, the hand failed to return to the original level of comfort. 
e. General observation. The subjects* evaluation of the various 
types of hand protection, taking into consideration both comfort and ease 
of manipulation of radio controls, are tabulated below: 
Type of protection 
1st Choice 
2nd Choice 
Heated gloves 
5 
2 
Fur mitten with liner 
1 
k 
Ski Trooper combination 
1 
1 
Total number of subjects 
7 
7 
The heated gloves were preferred by five of the seven subjects. One 
man, who selected the fur mitten with liner, apparently was willing to 
sacrifice some comfort for the dexterity afforded by this type of hand 
protection, in which the bulky fur outer cover could be removed quickly and a 
high degree of dexterity with some protection, provided by the close-fitting 
inner glove. This feature has considerable importance. 
3. Modification of Electrically Heated Gloves 
a. The electrically heated glove is an experimental model type 
P-223-1, manufactured by Pioneer Products Section, General Electric Company, 
Bridgeport, Connecticut. The complete glove consists of an inner wool glove 
with a single layer on the palm and a double layer on the back. The heating 
elements of flexible wire are fixed between the two back layers in the 
arrangement shown in Fig, I, The outer glove is an unlined leather shell. 
The current consumption for one pair of gloves is 5 amp* at 6 volts, A 
number of disadvantages were noted in the present experimental model, 
b. The power consumption of 30 watts required by a pair of the 
gloves is equivalent to a rate of heat production of 24 calories per hour. 
This is approximately l/3 of the entire hourly heat output of a quietly 
seated man and should be more than adequate to maintain comfort of the 
hands provided it could be efficiently applied. Further improvement 
requires more uniform application of the heat and better heat insulation ' 
outside the heating elements. 
3 £. Further indication of the need for improvement in the 
distribution of heat is evidenced by the inadequate protection which is 
given when handling cold objects. The palms, finger tips and thumb 
become painfully cold* 
d, The gloves offer quite inadequate protection when the 
electric current is not on and only poor protection when the voltage is 
low. For example, when the electric input was reduced to 16 watts, the 
hands quickly became painfully cold* 
e. The present wiring of the circuit with the gloves in series 
makes it impossible to use a single glove. Furthermore, if a short circuit 
occurs in one glove, both are rendered inoperative, 
fo The plastic guard over the battery clip becomes hard at low 
temperatures and consequently the clip cannot be opened or closed. 
4. RECOMMENDATIONS: 
a. Change circuit of the two gloves from a series to a parallel 
connection, 
b. Develop, if possible, a more uniform distribution of heat. 
£, Provide a better outer glove. 
d. Provide a guard for the battery clip that will be flexible 
at -40°F. 
4 RUBBER INSULATION 
OVER TERMINALS 
GLOVE WIRING 
(BACK) 
FIG I