0Burf 7 years ago ReplyUpvoteIt all depends. Are you using brush on or spray? Regular or water based? What are the climactic conditions? I have seen some brands that the label says is dry to the touch in about two hours but that doesn't mean it is ready for wet sanding. Personally, I wouldn't even think about doing it for at least 24 hours minimum. One test I use is to see if my thumbnail leaves a depression in the coating, if it doesn't leave a mark , I will test it with some fine 600 grit paper and if it doesn't ball up, then I will continue.If it is something you really don't want to take any chances with, wait 5 days and it should be okay if you are careful.