Preparing floor for ceramic tile [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


View Full Version : Preparing floor for ceramic tile

Ryan Patrick
06-24-2001, 10:03 PM
Hi. I have a few questions on preparing our concrete floor for ceramic tile. I removed 2 layers of linoleum from the floor that have been there for about 30-40 years, There is a hard black residue still remaining that won't come up (I tried soap/water/vinegar), as well as some while sticky, soft glue that has been coming up slowly but surely with scraping. Should I keep scraping, especially the black part, which is more difficult to remove. Is there any easier way of doing this? Also, we have some very fine, hairline cracks that are less than 1 mm thick in most spots. These seem to be level. Do we need to worry about this? Should we do anything to fix the crack. The building is very old, and the crack may have been there for years. The guy at HD recommended flex-bond mortar, since that's supposed to resist any possible small movement. Any advice would surely be appreciated!

Ryan Patrick

Sponsored Links

Bud Cline
06-24-2001, 10:31 PM
This sounds like a question for John......."Take it John".

("here the rim shot"?)

Bud Cline
06-24-2001, 10:34 PM
John I just noticed the "Senior Member" designation, do I get like a John Bridge coffeee mug or paper weight or something? How 'bout a key chain, ball point?

Rob Z
06-25-2001, 06:41 AM
Hi Ryan

The black residue is called "cutback adhesive" (I just learned that term). I have always called it "blackjack". I asked John this very question a month or two ago on this forum. He has successfully set tile over the blackjack for years using a high quality, latex modified thinset. The two brands of setting materials that I use most claim to be suitable for use over this residue, as long as the thick stuff is removed, usually by wet scraping.

It's possible to use a bush hammer to chip off the upper 1/8"-1/4" of the surface for the concrete, but that is time consuming and noisy.

Get all the loose stuff up with water and a scraper ( I use a long T-handled scraper I got at HD for about $20), then clean and mop the floor with something like Aqua Mix Heavy Duty Tile and Grout cleaner. Then set your tile with premium thinset.

As far as the cracks go, you could use a crack isolation product like Schluter Ditra or a Noble sheet membrane. These will cost about $1.50 per square foot for the material only, plus your time to install them. It sounds like your cracks are small and old, so things are probably stable now. You may be able to get by without using one.

If you have anymore questions, stop by and visit again.


John Bridge
06-25-2001, 04:03 PM
Hi Ryan,

Thanks for stopping by.

The flex bond will certainly adhere to the "cutback/blackjack/asphalt emulsion, but Versa Bond, which HD also sells will do the trick. Versa Bond is about 15 bucks per sack, while Flex Bond goes for around $25.

Don't know what the other glue is, but if it was not water-base, and I was having a very hard time removing it, I'd go over it also. My philosophy is if it won't come up, it won't come up.

As Rob indicated, the small cracks are a judgment call each and every time. Sounds like yours won't pose a problem, though. Make sure that when you are finished you have enough spare tiles to span the room in case there are problems down the road. You can always replace individual tiles.

06-26-2001, 03:49 AM
Before we go recomending a proprietary product, for a certain application, lets look at there recomendations.

Go to,click on installations systems, then click on exterior/interior slab on grade, and you will find they are recomending a latex additive with the thin set and their crack isolation product.

If you go to the home owner section, slab on grade, they only recomend latex additives in their good, better, best scenario.

Flex bond is the only product that they recomend to bridge cracks up to 1/16th of an inch. Could you anticipate spider web cracking? Probably. Do any of these products cover new fractures? I don't think so. How do you identify a new fracture from an old one? Does the salesman have to come out and approve the substrate?


[Edited by flatile on 06-26-2001 at 06:09 AM]