Our kitchen has 35-year-old flooring tiles, attached to a slab
with this black tarry stuff.
Any ideas on how I get this stuff off the slab so I can put down
new ceramic tiles?
My wife thinks I know everything, so I can’t just go to a tile
store and ask…
Thanks!
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Replies
The "black tarry stuff" is most likely cutback adhesive
It most likely contains some amount of asbestos, so don't sand, grind or anything else that causes it to be airborne
What I usually do is use a floor scraper that is sharp. Scrape up whatever you can to get it smooth. this will still leave the cutback residue in the concrete. You will need to use modified thinset that is rated for use over cutback
Wear a dust mask and close off the rest of the house, keeping the floor damp with water as you scrape.
There are some adhesive removers out there that are said to be for the cutback, my worry is that the solvent pushes the cutback into the concrete "pores" making for a poor bonding surface. YMMV do a google search if interested on "cutback adhesive removal"
I have also heard of using dry ice but have never tried it
I have also heard of gasoline and matches, have yet to try that either
sounds like asbestos to me. don't wear a dust mask, it won't do any good (asbestos particles are smaller then the pores in the mask). you need to get a respirators that is rated for fine particulates. $30 at hd. good luck..
I didn't ask the question ;)
Barry E-Remodeler
The 'cutback' is an asphalt-based adhesive, and it could very well contain some asbestos fibers.
Sanding, etc., is not very effective, as the tarry stuff quickly clogs any sander.
I like the idea of scraping off all that you can; perhaps the selective use of dry ice will help it come off in chips. You don't want to heat it, as it will just smear about.
I had such a floor, where the tiles had been removed. Looking for a 'quick fix,' I put down a nice coat of oil-based paint (Rust-O-Leum). Much to my surprise, the paint took a good week to dry. An entire week! The good news was that, during that time, the solvents in the paint softened the asphalt, and it flowed itself flat. All the trowel marks were gone!
Now, I'm not suggesting you paint the floor. I don't know how the paint would do with thinset over it. But, I am thinking that citrus paint stripper, covered with a plastic sheet, and allowed to work for a few days just might soften it enough for easy scraping. When scraping time came, I'd probably want a pail of kerosene handy for cleaning off the scraper. Then, once it's as scraped clean as you can get it, I'd put down more paint stripper, and layer some newspaper over it before putting the plastic down again. This time, maybe you'll get lucky and any remaining tar will wick up into the paper. Maybe; I'm just thinking here.
Thanks for all your thoughts! It looks like I should plan
on scraping, and maybe use low-odor mineral spirits to keep the
scraper clean.Apparently there is thinset rated to be applied over cutback,
so I have a HD trip planned...I'll buy good quality respirators for myself and my nephew, and
get to work!
Brooks,
A while ago I left a job on Friday nite with the homowners tackling the demo cleanup on their early 50's house.
Came back the next morning and looked for my broom. Found it. Instead of alot of fine bristles I now had one bristle.......
thick with black goo.
They had dumped a large bucket of water and used it to "clean up".
The water had softened the adhesive. Give it a try in a small spot.A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
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You're definately on the right track. I've done maybe 20 of such floors over the years and the ceramic tile is still rock solid to this day, as far as I know. That's to say, I haven't had any call backs, and a few of them were for customers I still get work from on occassion.
The important thing is to make sure and get any and all bumps or ridges. They're hard to see, and I keep a sharp scraper in my pocket while laying the tile, in case I run into any I missed.
There is no need to clean every bit of the cut-back from the concrete as long as you use the right type (and best quality) thinset. ~ Ted W ~
Cheap Tools! - MyToolbox.netSee my work at TedsCarpentry.com
Acetone, my favorite solvent.
Brooks-
I have successfully tiled concrete floors after stripping vinyl tile and cutback adhesive. As others have noted, be careful when removing the tiles and the adhesive because both may contain asbestos fibers. If you can, keep everything wet when you are pulling tiles - a spray bottle filled with some slightly soapy water can help, as can a small dust broom to push water under the tiles as they are being pulled up. The less tiles you break the better.
As far as getting adhesive off, I use scrapers and putty knives in combination with mineral spirits. You will use a lot of mineral spirits and a lot of rags/paper towels. Once you have the floor clean, clean it again with mineral spirits. Flood it on, and then use a stiff brush to really clean the concrete. Soak up the mineral spirits with more rags/paper towels. Repeat as necessary until the floor looks tar free. The concrete will definitely be darker than normal after the process, but it will be fine to tile. As a precaution, I always make sure to air dry anything saturated with mineral spirits before I dispose of it. I know it isn't likely, but the thought of a garbage can next to the house catching on fire is enough to keep me awake at night.
When tiling, use a modified thinset (one that's approved for going over cutback is even better). Do not skimp on thinset. Buy the best type that is appropriate for the job. There are others out there that recommend putting a skim coat of thinset over the whole floor (without ever stripping the cutback), letting it dry, and then tiling over that. I know it would cut down significant time in the process, but I've never done it so I can't recommend it.
By the way, if anyone is skeptical about my method of getting rid of the adhesive, the slabs I've worked on all absorbed water just fine after I was done cleaning them. I have not had a problem or a callback.
BK
Edited 10/21/2009 2:05 pm ET by bk24
Edited 10/21/2009 2:08 pm ET by bk24
Black goop that old probably contains asbestos.
We just replaced 2,000 sf of glue down carpet (on concrete) and used a floor buffer type tool to strip the old adhesive. It had a disc with about 6 carbide teeth, about 3/4" wide. Took many, many hours, but the concrete is smooth and clean. We sprinkled the floor with common sand and wax based sweeping compound. That helped to cut the goo and keep the dust down, but it was still very messy and loud.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
sounds like linoleum floor tiles - I use heat (torch or heat gun) to soften the tiles and the adhesive, peel them up with a putty knife, then follow up with solvent. Then I'd glue down a slip sheet (isolation barrier) over the slab, or at least over any cracks, before putting ceramic tile on concrete.
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Edited 10/21/2009 11:25 pm by Huck