I want to paint my basement walls & the walls (cement) were treated with water proofing paint (like Drylok) about 20 years ago. Can I paint over the top of this with regular latex paint or do I need to use waterproofing paint again? I know the Drylok stuff soaks into the concrete some. It used to come in just a dingy tan color & now I want to brighten up the walls for a work-out area. I will not be putting sheetrock over it. Any ideas out there?