Your friends at Northern Lights are correct. All the damage must be removed before coating. We start with a chemical stripper instead of abrasives to remove the damage. In many cases this is all that is needed. In others, we use abrasives to remove any remaining damaged coating or to remove physical defects such as scratches or pitting. For some commercial customers, they don't care about scratches or pitting. They are more interested in restoring clarity for safety reasons and cost.
We consider the 3000 grit as preparing the surface and don't do any polishing past that point. It's also true that the 2Ks are very thin and don't cover as well as some other coatings so we apply a second coat after a 5 minute flash off of the first.
ray6
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