abrading tile

[zman]

we will be laying about 700 sq ft of a 16" porcelain over some existing tavertine and glazed ceramic tile. i have been told we will need to abrade the existing tile and use a special "high bonding" thinset as well as a 1/2" notched trowel. the travertine has been recently sealed. as far as the "abrasion" work is concerned, i have been told a few things. they included using
(1) an acrylic stripper to remove the sealer, (2) sulfamic acid to etch the travertine (i was told the acid will not work on the glazed ceramic), and (3) grind the tiles with a 60 or 40 grit sand paper. if anyone has done this type of work before, i would appreciate hearing you the specific steps you followed and in what sequence. thanks.

[John Bridge]

I wouldn't do the acid. It will etch the travertine, but it's not necessary, and it might just loosen something up. If you use the highest flex thin set you can buy of any brand, it will stick to anything including glass. I'm not sure you need to scarify the existing ceramic either unless it has a very high gloss finish.

[Dave Bergerson]

I agree with John,get some of that high dollar thinset and do yourself a couple of test areas..When in dought I'm a scarifier.Be sure to test those sealed areas good.

[Bud Cline]

I'll 'third' that but the sealer could be a problem.

Oh...and by the way...that sandpaper isn't going to touch that glazed ceramic so save your money there.

[Cisco]

I'll "Fourth" that.....

I would either strip the sealer or use a commercial cleaner (TSP) to clean the stone and the ceramic. The acid would be a mess and probably not achieve any better results. I would definitely use a $$$ thin-set.


©

[zman]

we're using the strongest thinset made by custom - $28 a bag! i think bud is saying that the 60 grit sandpaper will not abrade the glazed ceramic. should i consider something more aggressive, such as a concrete grinder or just not worry about it and let the $$$ thinset do the job?

[John Bridge]

That would be Flex Bond?

What does the surface of the tile look like?

[zman]

it's a glazed tiled but not real shinny. i tried a 20-grit today with no effect. should i try a diamond bit concrete grinder?

[John Bridge]

My vote is to make sure it's clean and hit it with the Flex Bond. I can guarantee it'll stick.

[zman]

thanks john. by the way, i finished the master bathroom. i did the jacuzzi tub, the shower and put a heating element under the floor. i used "double dutchmen", as you suggested, on the face of the jacuzzi so i could have single pieces all around the top. i'll send you a photo.

[John Bridge]

yeah, I'd like to see a picture.

[zman]

this is an update on our "abrading tile" problem. first, bud was right. sand paper, regardless of the type of grit, has no effect on glazed tile. neither does sulfamic acid. the sulfamic acid worked well on the travertine though. we tried custom's best bonding mortar and were not happy with the bond after letting it cure for a week. our biggest fear was "popping tiles" at a later date.

as a final step, we rented a single disc concrete grinder with diamond bit blocks. (the single disc was much lighter and not as aggresive as a double disc). in any event, the concrete grinder wroked great! it did just enough to scarify the surface without grinding away chunks of the tile. it did create some dust. we covered 700 sq ft in minutes. just like running a vacum.

we also ended up using a special mortar that supposedly has a "sheer strength" rating of over 600 psi versus custom's premium brand that has only a 300 psi rating. we tested it and got great adhesion.

i know this all may sound like overkill, but i simply did want want to have to deal with "popping" problems in the future.