You should either strip or bead blast the concrete and thoroughly clean it.
Tile over cement block.
Clean the surface of any dirt or debris with a ph neutral cleanser and a sponge or scrub brush.
Yet this application does make sense since concrete is heavy solid and is typically thought of as an unbending uncompromising material.
First chip the bumps cracks and dents on the concrete wall with a hammer.
Mix surface bonding cement with water to a pasty consistency.
Used thinset and concrete screws to install the backerboard then redguard over the backerboard before tiling.
The easiest product to use on a cinder block wall is.
Remove as much debris as possible from the wall so the concrete.
Clean debris off the wall with water and a sprayer.
Ceramic and porcelain tile are so frequently installed at or above grade level on a cement board underlayment or directly on plywood that it almost seems novel to install tile directly on concrete.
How to install ceramic tile over painted block walls for a shower.
Kerdi board building panels can be used to create a ready made flat and plumb surface on the cinder block wall.
For application over an uneven concrete surface a lightweight waterproof construction board must be used as an alternative to concrete board in a tile installation.
Had to chip off all the thinset with an electric chisel.
But we had to install 1 2 inch tile backerboard to bring the tile up and over the tub lip.
You could set your tile right on the block if it is flat enough some block work i ve seen has convinced me that the masons were drunk on the job and there is no paint or other coatings that thinset would have a hard time bonding to.
If the paint comes loose so does the tile.
They are screwed into the wall and are waterproof and thermally insulating.
Then flush and fill the areas with cement.
Once the cement is dry apply the bonding agent that should give the surface a rough texture.
The backerboard provided a smoother surface to tile on.
Construction board panels are extremely light and easy to cut but they provide a very strong durable and waterproof surface on which tiles will be installed.
Wet a section of the wall again to.
Rinse the cleanser away with clean water.
Nail 3 4 expanded metal lath to the blocks with 1 1 2 to 2 inch concrete.