4. Marine microorganisms were responsible for the deterioraHon of (1) cotton and 

 manlla rope specimens, (2) burlap (jute fibers), and (3) possibly vinyl plastic tube 

 (NCEL No. 66). 



5. Electrical cable insulation composed of silicone rubber was deteriorated by the 

 nibbling and biting action of some marine animals. However, silicone rubber cement 

 used to seal the ends of the wire specimens was not damaged. 



6. The following materials in various forms and for various uses were not affected 

 by marine organisms: (1) rubber vacuum hose; (2) nylon nuts and bolts; (3) nylon 

 and polypropylene ropes; (4) ethyl cellulose cable clamps; (5) neoprene, butyl, and 

 natural electrical cable insulations; (6) various plastic laminated sheets; (7) glass 

 microscope slides; and (8) bisphenol-fumarate polyester resin laminate. 



CONCLUSIONS 



1. The following materials are susceptible to total biological destruction and are 

 not suitable for use in the deep ocean: untreated pine, fir, and plywoods (treated 

 wood may not be affected); manila and cotton ropes; jute fibers; and electrical 

 cable insulation composed of a silicone rubber. 



2. The following materials are probably not susceptible to biological deterioration 

 in the deep ocean: rubber vacuum tubing; acrylic sheet, nylon nuts and bolts; 

 nylon and polypropylene ropes; ethyl cellulose clamps; laminated plastic sheets; 

 glass slides; electrical cable insulation composed of neoprene, butyl, and natural 

 rubber, and polyvinyl chloride; and bisphenol polyester laminated plastic. 



3. The 3-foot-long plastic rods and tubes (except vinyl tube, NCEL No. 66), the 

 polyvinyl chloride pipe, and the electrical cable insulation (except silicone rubber) 

 may be suitable for use in the deep ocean environment if they are not placed in 

 direct contact with wood. 



FUTURE PLANS 



The research program to determine the effects of the deep sea environment 

 on engineering materials is continuing. 



A STU (11-2) which was exposed for a period of 13 months at a depth of 

 2,370 feet was recovered In May 1966. The materials on this STU are currently 

 being examined, tested, and evaluated for biodeterloratlon. A report on the 

 findings will be published. 



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