MATERIALS AND METHODS 



Two types of polytetrafluoroethylene (TFE) films and a saran film, 

 each with pressure-sensitive adhesive backing, were used in this study. The 

 information on thickness, width, adhesives, and costs is presented in Table 2. 

 These plastic films were selected primarily because of their resistance to sol- 

 vents and other chemicals, low water absorption, and moisture permeability. 

 In addition, they have a high electrical resistance and are nonflammable, non- 

 toxic, tough, and abrasion-resistant. The biggest difference between TFE 

 and saran is their cost. As shown in Table 2, TFE costs about 10 times more 

 than saran. 



Test Panels 



A total of fifteen 6 x 12-inch test panels was used in this study 

 (Table 3). Carbon steel, stainless steel, and K-Monel were selected because 

 they are known to corrode in seawater, the object being to determine if the 

 plastic films would protect these metals from corrosion and fouling. Marine 

 paint was applied to the carbon steel panels to determine if the pressure- 

 sensitive adhesive backing on the plastic films would stay attached to the 

 smooth painted surface for long periods of exposure in the sea and if the 

 strippable plastic films would give adequate fouling protection. 



Application of Plastic Films 



Before the plastic films were applied to the unpainted metal surfaces, 

 the panels were cleaned with alcohol to remove any grease and dust particles. 

 The eight carbon steel panels were sandblasted to a "white metal" surface, 

 and then four of them were spray-painted with the following paint system: 

 first coat — Formula 1 17, a pretreatment primer (Ml L-P-15328B); second 

 coat — Formula 1 19, a vinyl primer (Ml L-P-15929); third coat — Formula 

 122-82, a white cover paint. The cost of preparing the carbon steel panels, 

 including labor and material, was estimated to be $0.83/sq ft. 



It was slightly difficult to apply the plastic film smoothly over the 

 test surfaces without forming air bubbles underneath the plastic film, 

 especially when applied by one person alone. The glass-fiber coated with 

 TFE was much easier to apply than the skived TFE film or the saran film 

 because it was much firmer and stiffer to handle. The edges of the skived 

 TFE and the saran film tended to curl during the application process, thereby 

 making it difficult for one person to apply it smoothly over the test surface. 

 However, all the films could be applied fairly rapidly: it was estimated that 



