Paint over salt and it will eventually react with water to form blisters and delaminations. You can knock off salt crystals with abrasive blasting, but it takes water blasting to rid the surface of most of the invisible salt contamination. To deal with the remaining salt, specifiers have turned to zinc-rich coatings and epoxy mastics, said Carboline's Harrison. The zinc-rich coatings render the salts into insoluble and therefore harmless zinc chlorides, while epoxy mastics encapsulate the salt and cordon it off from moisture. Nevertheless, salt tolerance is not something the coating industry brags about.
Oil is another story.
Normally, you remove it with water blasting, sandblasting, or a chemical degreaser. But some of these methods don't go over well in sanitary-minded places like food and beverage plants and slaughter houses, since few people want to taste sand in their hamburgers. And besides, such surface preparation usually means taking a facility out of service. With a coating from Valspar called Vepok 500, however, you may be able to get by with just waterblasting and hand-scraping. The oil that remains is absorbed into the coating, which also tolerates tight rust.