I've laid mosaic tiles (about 1 inch square tiles in 1 ft square sheets) on a shower floor. The tiles had a paper backing with round holes that covered about 30% of the tile, so it was very difficult to get good coverage on the back of the individual tiles. In addition, the tiles are thick, about 0.5 inch, so they do not sit well. I ended up buttering the back of each individual tile. Now there is thinset squeezed up between a good section of the tiles, though even then the adhesion is poor and several popped off just by vacuuming.

Given the difficulty of removing the thinset from between the tiles, which are roughly square, but irregular with ragged edges, is it possible to fill in the rest of the gaps with thinset, instead of grouting? I used white multipurpose thinset, whereas I wanted almond grouting, so I was considering using a concrete stain to change the visible thinset color.

thanks
Rod

Welcome Rod,

Sorry you had a tough time installing the tiles. With experience you should be able to do better next time.

It would be best if you tried to cut out the excess mortar. A utility knife and damp sponge will do the trick. Although it is possible to grout a small area with thinset, it is difficult and very messy because thinset is pasty, and grout isn't.

Jaz

Just to add to Jaz's comments. I'm not sure how well thin set will take a grout stain either. It has lots of latex in it, and that would be more difficult to stain then grout. And, like Jaz mentioned, it's very difficult to wash off when used as grout, plus is shrinks.

I'm working on removing the thinset between the tiles, but it is a long and laborious process when dealing with several thousand tiles. My query was inspired by this information below.

(This is from http://www.mosaictilesupplies.com/installation.html)

NOTE: During back-buttering, it is common for thinset to push through the grout joint and rise above the surface of the tile once the sheet is applied to the wall. For this reason, professional installers "set in color", or use the same installation product as both mortar and grout. Check with the manufacturer of the thin set you choose in order to verify its suitability. If you choose not to set in color, you can remove excess grout as described below.

I'm guessing you know what you did wrong? You didn't beat the tiles into the mortar at all, or not good enough. Then you decided to back-butter and applied too much. Then you didn't or weren't able to remove all the extra mess.

You were worried for nothing about the paper backing. The thinset bonds to the paper too. If they are that thick, (1/2") are they stone as opposed to porcelain?

I checked the link that you supplied and found lots of disclaimers. They're talking about mosaics and glass tiles and face film mounted etc. Bottom line...they're just giving you tips and it's up to the installer to figure it out.

As for the "set in color" business. They are talking about an epoxy setting and grouting system. To install or grout the tiles you mix part A with part B, then mix part AB with filler powder part C to make either the mortar or grout. Use colored powder (grout) as part C for both steps and both the mortar and grout is the same color. Cost lots of $$$ and a royal pain, especially with mosaics.

Jaz

a similar thing happened to me when i was tiling my 2"x2" tumbled marble. after i put the tile on and pushed it into place with much force, the mortar squeezed out between the tiles, and in some places was out past the flush surface!

my wife took a pencil and just ran it down between all the tiles to remove the excess just after it was applied. then we grouted without any problems.

Knucklez