How should porcelain adhere?

[Peter]

Been doing a renovation on and off for the last 6 months or so. Done this floor at the start and it was decided this week that the door would open out so had to lift a few tiles. Although they were back buttered and solid bedded, they came up cleanly without much on the backs. Tiles weren't wet and stuck with an SPF. Is this normal with porcelain?

 

[bugs183]

Which SPF do you use, and do you use a thick mix when you knock up your adhesive??
When Porcelain first came out and the manufacturers had to reinvent the adhesives with polymers the Bal reps told us to use a slightly wetter mix than usual just to wet the polymers and to make sure they adhered to the tile.

 

[Peter]

Was a wetly mixed polymer modified Biscem. Not really lifted any of my own work so unsure of how it "should" look underneath.

 

[White Room]

I stopped using Biscem due to problems I had with it.....setting to fast and not holding on to the tile.

 

[Ian]

I had to lift a couple of chipped tiles from one of my jobs (something dropped on tiles), the adhesive used was Mapei proflex and the tiles had been down about 8 weeks, they came clean of the adhesive with minimal effort, tiles didn't even break. Bit of a worry really. I use webber most of the time now and this experience has really put me off proflex.

 

[Sean Kelly]

This happened to me a couple of weeks ago. I had to lift a tile the next day because it was chipped. When I smashed it out it was clean on the back. I thought to myself oh ****. but, the surrounding tiles were still well bonded to the floor. I used Toppfix rapid flex and i back buttered the tiles. The mix was not dry nor was it too wet. I was laying onto ditra too. The tiles are still down (and that was 2 weeks ago).

 

[Dougs Third Go]

could it be dust on back of tiles?

 

[bugs183]

Porcelain has always been a weird one to judge.
I've never had any problems with a porcelain floor, but when it has a good bang there's not much for those polymers to hold onto so the adhesive fails.
So it's hard to tell just how well the adhesive is working.

 

[nybor62]

did you back skim tiles

 

[Peter]

Yep, a fairly generous back skim. Tiles are all well stuck and don't sound hollow at all. Is there just nothing in porcelain to bite into?