1919.] 



THE INDIA RUBBER WORLD 



299 



Defense plant which made it possible to cut to any predetermined 

 length 100 lengths at one time. The machine once adjusted 

 was practically automatic in its operation, and only required 

 replacement of the rolls of tape. 



THE A. T. RESPIRATOR. 



The A. T. respirator mask (Figure 12) was one of the two 

 in the process of manufacture at the time of the armistice. It 

 tvas suitable for manufacture in rubber factories. The other 

 one. known as the K. T. respirator, was a sewed and cemented 

 face-piece and suitable for manufacture in the Gas Defense 

 plant. They were the same from the standpoint of the user, 

 and both were manufactured to obtain maximum production. 



The letters "A. T." are an abbreviation of the name "Akron 

 Tissot." This name was used because the mask made use of 

 a principle first used bj' a Frenchinan named Tissot and the 

 development largely took place at Akron. This mask was de- 

 signed to meet the rapidly developing requirements of gas war- 

 fare. The use of mustard gas by the Germans (this gas often 

 persisted in the ground from one to two weeks and continued 

 to give ofif toxic concentrations) made necessary long wearing 

 of masks — often ten to twelve hours. This was impossible with 

 the standard mask; at least 

 with many individuals, the 

 discomfort of the nose clip and 

 mouth-piece and the pressure 

 of the face-piece became un- 

 bearable. 



Mustard gas is most in- 

 sidious. A man can be exposed 

 to the vapors for twelve hours 

 and hardly be conscious of its 

 presence, with no apparent ill 

 effects, and then, a day or two 

 later, conjunctivitis of the 

 eyes, lung tissue destruction 

 and body burns will develop. 

 As a result of these conditions, 

 many soldiers would not wear 

 their masks a long time in 

 mustard gas or would use 

 only the mouth-piece, and eye 

 trouble developed later. 



In addition to the above 

 considerations, the vision obtained from the regular mask was 

 not altogether satisfactory. Tlie moisture from the face con- 

 densed upon the eye-piece and in spite of anti-dimming com- 

 pounds (not always used) it was necessary when wearing 

 the mask repeatedly to wipe the inside of the glass, by making 



-Analytical Rubber Laboratory, Long Isla: 

 New York. 



included better vision, better stretch of tlie stockinet in each 

 direction, less pressure on the forehead, elimination of pressure 

 upon the nose, improvement in harness, and reinforcement of 

 the lower face-piece to prevent collapse when breathing. These 

 improvements were made as a result of tests upon soldiers in 

 gas and upon advice of the American Expeditionary Force, which 

 had been supplied with samples as they were developed. The 

 two rubber companies built splendid gas chambers at their plants 

 and thus afforded immediate facilities for testing. As an indica- 

 tion that this mask more nearly met requirements, a quotation 

 from an American Expeditionary Force cabled report is given : 

 "Six men wore these masks continuously for 29}/^ hours and 

 took them off only because ordered." 



During May and June a production of the earlier model was 

 started in order to have production facilities available when the 

 final design was adopted. The early method of manufacture 

 was to cut the sheet stock to a flat pattern, apply the stockinet, 

 build in semi-cured lens frames, form the seam under the chin, 

 reinforce the edges with gum strips, and cure on an aluminum 

 form in open steam with or without wrapping. This method 

 yielded fairly satisfactory results on the earlier models, but in 

 the final design the amount 

 of contact with the face had 

 been sacrificed to obtain ci")m- 

 fort and therefore dimension 

 requirements had to be fnl- 

 filled within close limits. The 

 metliod described did not yield 

 a good product within the^e 

 limits. 



The period of July to Octo- 

 ber was employed in over- 

 coming manufacturing difficul- 

 ties which included the follow- 

 ing: 



1. The procurement of 

 standard dimension curing 

 forms in the necessary sizes. 

 (See Figure 5.) 



2. The procurement of lens 

 frame molds which would 

 yield the prope.'- design of 

 semi-cured rubber lens and. 



hold the register and gage. 



3. The development of manufacturing methods which would! 

 rield a product satisfactory in dimensions. 



In connection with No. 1 the pattern makers fotmd it diffi- 

 cult to make proper allowances for shrinkage in making the 



use of a pocket in each side of the face-piece. Therefore, the aluminum curing form. It was necessary to change the source 



of supply several times. 



With respect to No. 3, the rubber industry showed remarkable 

 fertility of ideas and ingenuity of method with regard to methods 

 of manufacture. It would require the space of a whole article in 

 itself to describe the methods involved. Contracts were let to 

 different companies and as many methods were employed The 

 wrapped cure was adopted in one way or another throughout. 

 Some obtained results with one cure and by use of templates 

 and guides attached to the curing form, which confined the flow 

 of stock and located harness tabs. Others used variations of 

 the two-cure process in which trimming was done after semi- 

 cure and correct dimensions thus secured. Ingenious diaphragm 

 and air-bag curing methods were employed and at the time 

 of the armistice the mold mask began to show promise. The 

 Aluminum Company of America worked out aluminum molds by 

 successive casting of wax, plaster of Paris, cast iron, and 

 aluminum. This method, in the opinion of the writer, will have 

 a more general use for various irregular shapes which may be 

 needed by the industry. 



problem of design involved was to achieve much greater face- 

 piece comfort, to eliminate the no§e clip and mouth-piece and 

 make better vision possible. 



Much preliminary work had been done by the Bureau of Mines 

 along these lines and in April, 1918, a model was turned over 

 to the Gas Defense Service. It was hand-made of sheet rubber, 

 reinforced and protected by stockinet on the outside, provided 

 with harness of pure gum straps and arranged to lead all incom- 

 ing air against the inside of the eye-pieces before it was breathed 

 by the soldier. This arrangement (the Tissot principle) kept 

 the eye-pieces comparatively free from moisture and with the 

 use of anti-dimming compound, practically perfect vision resulted. 



While this mode! embodied the desirable elements, much de- 

 velopment work was necessary before all requirements could be 

 satisfied. Accordingly, arrangements were made in April to 

 carry on this work at the plants of The B. F. Goodrich Co. and 

 The Goodyear Tire & Rubber Co. in Akron. 



By July 1, 1918, a model had been developed which eliminated 

 some of the defects of the early designs. These improvements 



