Prep and painting over previously painted concrete floors
I’m getting conflicting information surrounding prepping and painting over a previously painted concrete floor. Here’s the situation: I’ve got a concrete basement floor that’s been previously painted multiple times with what appear to be different types of paint. Some areas were bare concrete, some areas have what appears to be two different coats of 50’s or 60’s vintage epoxy paint that are pretty well adhered. The previous HO decided to spray a coat of cheap latex paint over the whole mess. Even something as simple as a combination of spilled water and boot scuffs is causing the last layer of latex to come off. I’ve started to use a water based (non methylene chloride) based concrete and masonry paint remover to remove the layers. Its working slowly but it’s a ton of work and is giving me very uneven results. What’s the best method to prepare the floor for an eventual coat (or coats) of epoxy or other concrete paint? Are there specific cleaners and or primers to use? Does this whole mess need to be stripped back to bear concrete? I’ve heard that sanding with a course grit will suffice. Unfortunately pressure washing the area isn’t the option because a good chunk of it is in a finished space.
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The problem is, of course, that any poorly-adhered paint is apt to peel once the new coating is applied.
(Well, that's just part of the problem. The other part is that, by definition, all paint on concrete is "poorly-adhered", or will be, as soon as you re-coat it.)
Have a chat with a tool rental house. There are machines made that look sort of like a floor buffer, but actually hammers the floor face. This machine is used to prepare concrete for painting. It ought to not onlt remove any paint, it ought to remove and 'sealer' and give the slab a nice, clean face for the paint to grab.
Then of course, you want to follow with an extremely thorough vacuuming and use an epoxy-based paint specifically intended for floors. Want a little better traction? Get a commercial-kitchen sized salt shaker and sprinkle the still 'wet' epoxy with white silica sand.