Apply even pressure to force the air out of the thinset and to make firm contact between the layer of thinset on the tile and the layer on the wall.
How to stick tile to concrete wall.
The ceramic tile installation procedure illustrated in the photographs that follow involved the following steps.
You can install them removing the back paper to expose the sticky part of the tiles.
Spread a smooth layer of thinset on the back of the first tile and press it firmly into the notched layer on the wall.
Make sure that the concrete surface is clean and will adhere to the tile.
Scrape the mastic with the notched side of the trowel.
How to stick tiles to the wall.
Clean the wall surface thoroughly removing all loose and granular materials to give a sound surface.
When the entire wall is finished tap tiles that are slightly raised with a rubber mallet.
For most tiles the depth of the notches should be.
You can keep installing the tiles working from the center towards the walls.
Seal the wall surface with a tile mastic compatible polyurethane sealant and let that cure for a few days.
Check the tile for plumb and level then proceed to the next tile.
Let the cleaned wall dry.
Use spacers between each tile for the grout.
Start by putting tiles on the bottom of the wall and work your way up.
Spread mastic generously over a section of the wall that you can cover with tiles in about an hour using the flat surface of the trowel.
Twist the tile until it is straight and even with both chalk lines then press it.