1116 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1957 



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Fig. 8 — A test rack used in marine borer test prior to exposure. Note bait 

 piece of untreated wood fastened across middle of test rods. 



it is possible to determine whether the organisms can attack the samples 

 directly from the water. Fig. 8 is a photograph of one of the racks prior 

 to exposure in the sea. The lower 10 inches of the rods are embedded in 

 the bottom sediment where bacterial action is relatively high. Thus, each 

 sample is subjected to water exposure and possible borer attack through 

 the transition zone from water to sediment and into the generally 

 anaerobic conditions of the sediment. 



Due to the short time that these tests have been in progress, it is im- 

 possible to draw extensive conclusions, particularly with regard to micro- 

 biological activity. Long exposure times may bring about physical or 

 chemical changes in a material which may render it more, or less, sus- 

 ceptible to attack. However, until more detailed data are available, 

 some interesting preliminary examples of biological activity can be cited 

 which may be of some interest and serve to illustrate the kind of informa- 

 tion which is steadily being acquired. 



With but two exceptions, there has been no direct penetration by 

 borers, or microbiological deterioration, of any of the plastics. Polymono- 

 chlor-trifluoroethjdene in the form of a 0.0035 inch-thick tape wrapped 

 on a f-inch diameter Lucite rod for exposure, was penetrated at one 

 point by a pholad. This attack occurred after three years of exposure at 

 Daytona Beach. Apparently the mollusk bored through an accumulation 

 of calcareous fouling and then progressed through the plastic into the 



