Otherwise you do.
Thinset over painted floor.
Paint used on concrete will not bond with the tile adhesive.
It must be easy to work with and it must adequately fill in gaps between the tile and the substrate.
How to use thinset morter to resurface concrete.
Cracks and gaps can be filled with portland cement based fillers.
Unfortunately the tile cannot be adhered directly to the painted surface.
Whether you have cracks chips or just a stained concrete slab thinset helps cover the old surface and create a new problem free area.
Mapei ultrafor plus data sheet says to use their keraply latex admix in lieu of water when going over impervious surfaces.
The house was built in the late fifties and the slab floor has been painted at least once.
All paint will need to be removed before you begin installing the tile.
Whether wall or floor tile that tile needs to thoroughly stick to its base surface demands placed on tile adhesive are both extensive and steep.
The safest way to approach questionable concrete is not to cover it over with cbus but to fix the concrete.
Mortar cannot be installed directly over painted concrete itself.
The floor is a 4 inch poured concrete slab over an unheated utility room.
Installing tile over painted concrete adds a few extra steps to your tiling job.
Not that they would endorse going over an oil based paint what you should do is scarify the paint off the floor.
The polymer modified thin set mortars might bond to a latex paint but not an oil based paint.
This surface is called a scratch coat.
Tile cannot be attached directly to painted concrete as the thin set will not adhere well to the paint.
Tile adhesive is expected to hold the tile in place not just for years but for decades without fail.
First a surface more textured and solid must be applied over the painted concrete.