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joshn: You need to use an acid product to remove the remnants of silica from the sand that are stuck in the tiny craters of the steel, or in this case cast iron grain. If you don't, they will draw moisture from the sir and opo underneath your paint down the road. I like to use any of the phosphoric acid products available at the building supply and car parts stores, like Ph-Opho-Ric+, but NOT MURIATIC ACID. The H3PO4 (Phosphoric acid) will dissolve the old sand deposits, remove any of the red rust that is forming on the fresh metal and convert it into the inert black oxide which will be stable and paintable, and inhibit further rusting by providing a thin phosphate coating. Now, you still should not store those parts near anything like table salt, potassium salt, tire calcium, side walk ice melter (same as tire calcium, CaCl3), nitrogen fertilizer, other ammonia products, etc. Not near a strong oxidizer, see? You really need to prime those parts as soon as you can or at a minimum get some H3PO4 and treat them. If you are not going to prime them right away, then oil them and degrease them later prior to paint. Frank Frank
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