surface to which additional coats may be applied if necessary. When plastic is 

 applied too dry, a pebbly or rough surface is obtained. The use of a retarder is, 

 therefore, not recommended except under extreme conditions. 



In cases in which either a thinner or a retarder is used, care should be exercised 

 in the handling of these explosive materials. The operation should be performed 

 in the open air, if possible, and the suggestions listed under the heading of Safety 

 should be carefully followed. 



Sources of Supply 



All the materials just discussed can be obtained from the manufacturers of the 

 basic vinylite plastic film, who are the authorized suppliers of formula OS-3602 

 to the Navy. The names of these firms are listed below, together with the trade 

 names of the products, similar to OS-3602, currently being manufactured by them. 



Name of manufacturer Trade name of product 



R. M. Hollingshead Corp., 840 Cooper St., Camden, N. J Cocoon. 



Better Finishes & Coatings, Inc., 268 Doremus Ave., Newark 5, N. ] . . Liquid Envelope. 



Zapon Division, Atlas Powder Co., Stamford, Conn Brevon. 



Stoner-Mudge, Inc., 2000 Westhall St., Pittsburgh 12, Pa S-1971 Strippable Coating. 



It is recognized that this list is not complete and that other manufacturers of 

 plastic materials can supply products similar to OS-3602. It is suggested, how- 

 ever, in view of differences found in the various products tested by the Depart- 

 ment that care be exercised in selecting new products and that thorough tests 

 be made in order to determine the adaptability of the product being considered. 



When stored in airtight containers, vinylite plastic deteriorates very slowly and 

 may be kept for relatively long periods of time. Unopened material usually will 

 remain in sprayable condition when carried over from one season to the next. 

 It need not, therefore, be purchased in extremely small quantities but can be ob- 

 tained in sufficient quantities to justify a reduction in price. 



EQUIPMENT 



Plan for Efficient Application 



As a result of its experimental work the Department found that the most effi- 

 cient application of this material was obtained when two men, working as a team, 

 used equipment supplied by air pressure from one large-type compressor. This 

 permits the use of two sets of three spray guns, one gun out of each set being 

 used more or less continuously. Each gun is connected to a pressure pot by 100 

 feet of both % 6 -inch air and ^4-inch fluid hose. The pots are attached to the com- 

 pressor by 50 feet of 7 / 16 -inch air hose, thus giving a combined working range of 

 approximately 150 feet. This type of operation requires air pressure for long 

 periods of time. A compressor rated at a minimum of 60 cubic feet per minute 

 at 100 pounds pressure was used by the Department. 



Compressors 



In large operations where spraying work will be performed over a period of 

 several months, it is desirable that an even heavier type of compressor be used. 

 Experiments indicate that a compressor delivering approximately 100 cubic feet 

 per minute is needed in view of the heavy load on this equipment. It is possible 

 that a slightly higher tank pressure might also be advantageous, considering the 

 length of hose used and the corresponding loss in pressure. It is believed that a 

 compressor capable of maintaining a tank pressure of 125 pounds would deliver 



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