3. Two types of lacquer (vinyl and chlorinated rubber) form tough, 

 durable films and are easily topcoated because solvent in the applied 

 coating softens the existing coating. 



4. Chlorinated rubber coatings cure rapidly so that they can be 

 utilized effectively where unpredictable rains or fogs limit times of 

 coating application and curing. 



5. Epoxies form tough, protective finishes, but the surfaces chalk 

 freely in sunlight. 



6. The polyamide-cured epoxies are more tolerant of incomplete 

 surface preparation than other epoxies. 



7. The chemically cured urethanes also produce tough coatings. 



8. Aliphatic urethanes have good weathering properties and, thus, 

 are sometimes used over epoxy primers to improve the exterior weathering 

 of the coating system. 



9. Zinc-rich coatings can give long-term cathodic protection to 

 steel. 



10. Inorganic zinc-rich coatings have better abrasion resistance 

 than the organic zinc-rich coatings, but the latter have better topcoat- 

 ing properties. 



Coating selection is summarized in Table 7 and discussed in more 

 detail in Reference 8. Coatings applied in three or more coats at dry 

 film thicknesses of 6 mils or more will give optimum barrier protection 

 if free of voids (holidays). 



Galvanizing is like a zinc-rich coating in that it also protects 

 steel from corrosion by cathodic protection. Zinc-rich coatings weather 

 better in marine atmospheric environments and are more easily applied 

 and topcoated in place (Ref 9) than galvanizing. Thus, a pretreatment 

 (wash) primer is used for alkyd systems on galvanized steel. A zinc 

 dust-zinc oxide pigmentation rather than a zinc chromate or red lead 

 pigmentation is generally used in alkyds that are applied over 

 pretreatment-primed galvanized steel (Ref 6) . Specially formulated 

 epoxies can also be used over galvanized steel. It is desirable to keep 

 a galvanized or inorganic zinc coating as a permanent primer protected 

 by a topcoat to avoid preparing the underlying steel for coating repairs. 



If aluminum structures are to be coated, an appropriate pretreatment 

 (wash) primer, a zinc chromate alkyd primer, and an alkyd topcoat can be 

 used (Ref 6) . Even greater protection will be received from a coating 

 system of pretreatment primer, epoxy primer, and aliphatic urethane 

 topcoat. 



Coating Antenna Guy Lines 



Galvanized steel wire ropes are usually used to guy antennas and 

 other towers, although aluminum-coated wire may be more corrosion- 

 resistant when proper precautions are taken (Ref 10). In a CEL study 





