Mapei Eco Prim Grip for tile on tile job

[melmak]

Hi. I am planning tile on tile job, by laying glass mosaic tiles on existing glossy tiles in the bathroom shower area. The materials I have bought are Mapei Eco Prim Grip, Mapei Aquadefence for membrane. I also tried to remove glossy surface with sanding machine (240 grit), but didnt notice any difference - the old tiles are still smooth and shiny. Today, I tried to apply the primer Mapei Eco grip for a couple of tiles, and afer a few hours I tried to remove it with a rag and some water. And it was gone. Is it supposed to be like this? I imagined it would stay even with application of water. Or am I doing something wrong? I really dont want to have the job done and then see the tiles to fall over the wall. Please advise. Thanks everyone.

 

[Dave]

If it removes that easy once dry , then the tiles must’ve been contaminated to break the bond , this stuff usually sticks like sh*t.

 

[melmak]

You mean it was not clean enough before application of the primer?

 

[Dave]

You mean it was not clean enough before application of the primer?

Could be yes.

 

[melmak]

It is not that it is very easy to remove it. It stays on the tile wall but I can still scratch it off if I make the dried primer wet with a rug or if it is humid in the bathroom after taking shower. Is it supposed to be like this? Or afte being applied, it cannot be removed from the tile at all? I just want to make sure my mosaic tiles wont come off after some time. As to contamination, do not think it could be the reason - I cleaned them well.

 

[melmak]

Thinking of roughing the surface of the tiles with angle grinder with a disc for steel. Do you think it would work?