I am trying to put ceramic tile on a basement floor that has bee painted with an oil based floor paint. My tiling contractor is nervous about doing it. I rented a machine to scrape the paint off, but the paint is so well adhered, that it took me 10 hours to strip only a fraction of the area. Should I be concerned with leaving the painted surface? If so, what preparation alternatives do I have?
CKW:
Your tiling contractor is concerned about how well the thin set will stick to the paint. On the one hand, he can add the recommended latex "additive" (pronounced "glue") to make the thin set stickier, but there's a question in his mind that the latex glue will stick to the oil based paint well.
The other thing is that if the cement gets wet after a heavy rain, evaporation of the water out of the concrete will lift the paint, and that'll be the end of the floor. The other side of that coin is that oil based paint doesn't breathe, so it would appear that this concrete has never gotten wet from groundwater. If it had, it would have peeled off by itself.
The fastest working stripper to use on oil based paint is a product called "methylene chloride", but I've never used it, because I don't often use oil based paint. I would find out more about it, including safety and ventilation recommendations when using it. I know there are paint strippers that don't have any methylene chloride in them that claim to work as well as methylene chloride, but I've never used them either.