3.6.2.3 Chemical Paint Stripping 



Antifouling paint may be chemically stripped rather than grit blasted or 

 sanded. The methcd is used by commercial yards for delicate equipment 

 such as sonar domes, antennas and deck machinery. Small articles with an 

 intricate surface may be dipped in some yards. The disadvantage of the 

 process is that the resulting combination of paint and stripping chemicals 

 often has the consistency of jelly or thin putty, is frequently caustic 

 and difficult to handle. There is some anecdotal evidence that the 

 methods is perceived as preferable or safer than hand sanding by the 

 private boat owner (i.e. Washington Post editorial February 2, 1986 by 

 Angus Phillips) . Nevertheless, the chemical strippers have not gained 

 wider popularity due to the tendency of the chemical to dissolve the 

 gelcoat of fiberglass boats along with the old paint film. 



3.6.2.4 Burning 



Paint removal by heating is more frequently done on wooden hulls or metal 

 hulls than on fiberglass hulls. A new technology has been developed by 

 Laser Technologies in Ann Arbor, MI which uses lasers to burn the paint 

 off large commercial ships. Laser Technologies claims that all the paint 

 film is converted to vapor, that there is no solid residue to dispose of 

 as is the case with grit blasting. 



3.6.2.5 Paint Waste Disposal Practices 



Spent paint containing toxic constituents is removed, along with iron 

 oxide and dead marine organisms from ships during grit blasting and 

 sanding. This residue is either collected or it will be washed, pushed or 

 blown into uncovered drains or into coastal waters. The Navy has tested 

 waste abrasive grit containing tributyltin employing the extraction 

 procedure toxicity test and has determined that grit blasting waste is not 

 a hazardous solid waste. The Environmental Protection Agency has reviewed 

 the Navy findings and concurred with the Navy's determinations (U.S. 

 NAVSEA, 1984) . Therefore, blasting residue can be collected and disposed 

 in an approval landfill. 



3.7 QUESTIONS TO BE RESOLVED 



Total antifouling paint production is well established. How much of the 

 biocide reaches the environment and by what routes is a major unknown. A 

 second unknown is what portion of the removed paint is still toxic, and 

 what portion of that reaches the aquatic environment. Boat work tends to 

 be performed where boats are kept. The relative contributions of boat 

 maintenance and boat mooring as sources of butyl tin into the environment 

 needs to be investigated more thoroughly. 



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