Table 5 Performance of Plastic Film Coverings on Test Panels 



Test Panel 



TFE Films 

 (glass-fiber and skived) 



Saran Film 



No Film 



Remarks 



Unpainted carbon steel 



The TFE films were found adhering to 

 the surface over a major portion of the 

 sandblasted panels. In some areas where 

 seawater had penetrated the plastic at 

 the overlaps and through small puncture 

 holes, the plastic film did not adhere to 

 the metal due to red rust formation. The 

 surface of the metal underneath the 

 plastic film was protected from corrosion 

 and fouling; stripping revealed the original 

 sandblasted bright white metal (Figure 6). 

 The plastic films could be easily and 

 rapidly peeled off the metal panel in 

 large sections. 



Saran film was found adhering 

 to the surface of the sandblasted 

 metal. Because the pressure- 

 sensitive adhesive material was 

 securely attached to the surface, 

 it was very difficult to remove 

 the plastic film. During the 

 removal process the saran film 

 would tear off into small pieces. 

 However, the metal surface 

 underneath the plastic film was 

 corrosion free. 



The control panel was severely 

 corroded with a uniform distri- 

 bution of red rust over the entire 

 panel. Underneath this layer of 

 red rust there was a layer of 

 gelatinous black iron sulfide 

 corrosion products. Sulfate- 

 reducing bacteria were found 

 associated with such corrosion 

 products. 



The surface of a newly sandblasted 

 carbon steel panel should be covered 

 immediately with a plastic film. The 

 pressure-sensitive adhesive backing on 

 a plastic film will not adhere too well 

 over a corroded surface. 



Painted carbon steel 



The TFE films were found adhering nicely 

 to the surfaces of the painted panels. The 

 films could easily be removed in large 

 sections from each panel in about 3 minutes. 

 During the removal process, where the 

 baseplate of the barnacle adhered to the 

 plastic, the plastic would rip around the 

 edges of the base. The painted surface 

 underneath the plastic film was very clean 

 as if it had never been exposed in the sea 

 (Figure 8). A small section of the paint 

 underneath the protective film was 

 exposed to biological growth when the 

 plastic film was destroyed by the 

 abrasive action of the ceramic insulator 

 which held the panel in place. 



The saran film was strongly 

 adhering to the surface of the panel. 

 The film with biological growths 

 could be removed easily from the 

 surface of the panel in fairly large 

 sections. 1 1 is advisable to remove 

 all of the barnacle shells attached 

 to the plastic film before peeling 

 because the plastic will start to tear 

 at the site of barnacle attachment 

 during the removal process. The 

 edges of the plastic adhered very 

 well to the metal and painted 

 surfaces. 



The control panel had the 

 heaviest fouling growth 

 among all the test panels. The 

 barnacles growing on the 

 painted surface were extremely 

 difficult to remove. Nearly all of 

 the barnacles were broken during 

 the removal process and their 

 baseplates remained attached to 

 the painted surface. Considerable 

 time was spent trying to remove the 

 baseplates of these barnacles 



The surfaces of the protected panels 

 were so clean that the panel could be 

 recoated and resubmerged in the sea 

 immediately. On the other hand, the 

 control panels probably would have 

 to undergo extensive reconditioning 

 before exposure. 



