Kicking off slate project [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


View Full Version : Kicking off slate project

02-18-2010, 01:36 PM

You got me through my last project with flying colors: custom shower pan using the PVC liner and the dry pack and all that good stuff. You guys rocked it out and I'm now back with a slate question.

Laying Adoni Black slate. Peeled up linoleum from the concrete slab and I'm ready to go. Have read to use the latex primer on the concrete floor first. Then the latex-modified thinset to set the floor tiles (6x12). What size/type of trowel btw?

Then using the same method on the backsplash wall - only using much smaller tiles (2x6). It is painted drywall - can I go right over it with the thinset then the slate?

Was told to seal everything first - floor and wall - then grout. Am I on the right path? Any other peculiarities I should be aware of? Thanks guys -

JB (not the real one!) :)

Sponsored Links

02-18-2010, 03:18 PM
I'm not sure about the latex primer on the floor. Instead, scrape up all the old adhesive until only stain remains on the slab. Then use a modified thinset rated for use over cutback adhesive. (this presumes the adhesive is black, if yellow or brown, scrape until water soaks into the slab, then use a good modified thinset). The size notch will depend on how well the tile thickness matches from box to box and tile to tile. Better match, smaller notch. Same is true about slab flatness. Flatter slab, smaller notch. Without kn owing anything else, I suggest you have a 1/4x1/4x1/4 and a 1/4x3/8x1/4 square notch trowels handy. Use the one that gives you 100% coverage and least amount of squeeze out in the grout lines.

Yes, you can thinset your smaller slates on the wall with modified thinset.

Either seal the slate, or tape the surfaces. Keep the sealer off the edges so the grout will stick in the groutlines.

02-20-2010, 06:55 AM

Thank you for the advice. Couple of follow up questions if I may:

1. Can you explain the taping process a little more? Its a small bathroom floor and if that is the best way to keep the grout off the tiles I will do it -(?)

2. The sealer is have is "Premium Gold Water Based Slate and Quartzite Sealer." Okay or should I get a urethane or other chemical based? Seems like I remember reading that water-based was not the preferred choice?

3. Do I need a scratch coat on the floor before I butter the slate?

4. I am using a sanded grout. Do I need to use the 'flexible grout admixture' I was sold? It says on the instructions to use this product instead of water. Just want to make sure I wasn't sold a bill of goods here!

5. I have the Felker TM saw - bought it on reccomendations here! Love it! Do I need to buy a stone blade for this slate project - or can I get away with the one I used for my last ceramic project?

THANK YOU EVERYONE - :) You guys (and gals!) give us DIY'ers the confidence and information we need to install a quality project and this site is awesome --

JB (not the real one!) :)

02-20-2010, 10:11 PM
Hey guys.

Sorry to be a pest - just wondering if any pros want to weigh in....hoping to start construction tomorrow... ;) :bonk:

Thanks so much!!

JB (not the real one!)

02-20-2010, 11:38 PM
Hey JB (not the real one) :D

1. I believe Bob was talking about simply placing tape on the face of the slate to assist in keeping grout off the face of the tiles as you are grouting. I prefer to use a good sealer on the slate before grouting and that will usually allow you to wipe the grout off the face fairly easily.

2. I prefer a urethane-based sealer but the Premium gold should work fine for you.

3. You need to comb thinset on the floor with a full coat (not just a scratch coat) AND back-butter the slate to get full coverage and a proper bond.

4. I'm assuming (and I know better) that the 'flexible grout admixture' you were sold is grout boost - I don't use it and personally don't like it. However, that is simply my opinion, there are many pros around here that do use it and like it.

5. The blade you used for your ceramic should work fine for your slate.