1. Possess high specific adhesion, permitting satisfactory 

 performance over clean sandblasted metal. 



2. Have high chemical resistance. 



3. Exhibit satisfactory wetting properties when applied to 

 the metal to fill and penetrate rather than bridging 

 crevices, pits, and pores found in most applications. 



h. Contain high solids for coverage and provide adequate 

 protection to sharp corners and edges. 



5. Have minimum of drag in brush application and possess 

 good spray properties. 



6. Perform satisfactorily over old oxidized painted surfaces, 

 rusty metallic surfaces, and even slightly damp surfaces. 



7. Show compatibility with various generic types of topcoats. 



8. Contain adequate amounts of inhibitive pigments. 



9. Dry to a tack-free stage in a reasonably short time. 



10. Possess satisfactory weatherability in the event finish 

 coats are not to be applied for three to six months. 



Although all of these characteristics may be difficult to obtain in a 

 primer suitable for marine structures, they are, nevertheless, desirable. 



Post curing inorganic primers such as zinc-lead silicate for steel 

 are stated to have a long and proven record in corrosion prevention and 

 to have performed outstandingly in the chemical and marine industries, 

 either top-coated or bare (Gelfer, 196^). Other qualities stated for 

 post-cured inorganic primers are: 1. excellent acceptability of topcoats; 

 2. ability to be cured quickly and effectively under varying conditions 

 of temperature and humidity. The principal disadvantages of post-cured 

 inorganic primers are the added cost and processing required in applying 

 the curing agent and removing the residue from it before further coating 

 can proceed. 



A post-cured zinc-lead silicate primer performed satisfactorily for 

 18 months when used as a control for testing self -curing inorganic primers. 

 Panels coated and scored showed little or no corrosion in the scored area 

 and were otherwise unaffected (Gelfer, 196^+). 



In other tests by the U. S. Naval Civil Engineering Laboratory (Drisko 

 and Brouillette, I965), a post-cured inorganic zinc silicate primer has 

 provided excellent protection to steel in shallow seawater for two years 

 regardless of the deterioration of the topcoat during this period. In 

 these tests, the vinyl phenolic primer coat did not adequately adhere to 

 the zinc silicate primer. 



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