preparing concrete for ceramic tile


  #1  
Old 10-08-00, 05:25 PM
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I have removed wood flooring from a concrete slab in preperation for laying ceramic tile.I removed the adhesive with a chemical remover.I read on the mastic instructions not to use on concrete if water will bead on the concrete because it will not stick.Water does bead on my slab,even though I cleaned it and scraped it.Any suggestions?
 
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Old 10-08-00, 11:03 PM
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Maddie:

Every time I mention the word "acetone" someone jumps all over me for telling you new recruits about the solvent that will make your life easy. They jump on me because the think it's toxic and it'll make your unborn children have the IQ of an average chimpanzee.

I've been using acetone for years, and although I have no children, I can still type 40 wpm, which puts me well ahead of your average chimp.

I would apply acetone to that adhesive, then I would apply a steel brush vigorously, then I would pick up the acetone and disolved adhesive with a sponge and bucket of water before the acetone had a chance to evaporate, which is pretty quick.

Try that.
 
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Old 10-09-00, 11:35 AM
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Maddie:

I should perhaps explain that when typing the previous post I had been indulging in homemade wine more liberally than I normally do, and that's why it kinda came out the way it did. Please forgive me if you felt that it was inappropriate.

Acetone is a strong, very volatile and very flammable solvent, and it should be used with care. It has a strong smell to it, and you should provide good ventilation to avoid light headedness when using it.

However, two attributes that make acetone ideal for this kind of work are that it cuts through solvent based adhesives rapidly, and it's miscible in water, which means you can clean the dissolved adhesive up with a wet sponge. Acetone evaporates very rapidly, so the best way to do this work is to apply the acetone to the floor with a squeeze bottle, spread it with a steel bristle brush over an area of about 1 square foot, agitate the adhesive with the steel brush to accelerate it dissolving into the acetone, then wipe up with a wet sponge to suspend the dissolved adhesive in water before the acetone evaporates, and then wipe up the water with a damp sponge.

Be careful with acetone near any kind of vinyl flooring or acrylic paint or floor wax. Acetone dissolves dried latex paint, floor wax and vinyl composition tiles rapidly. It causes sheet vinyl to swell up, but those few times I spilled acetone on sheet vinyl, the swelling went away without apparant harm to the flooring. It's safe over plastic laminate counter tops, nylon and polypropylene carpets, and it won't damage the baked enamel finish on a steel bathtub.

If you think that you can get more adhesive off with scraping, keep your use of acetone to a minimum by using a 4" flooring razor to shave the adhesive right down to the concrete. Any flooring installation supply store will sell these, and any place that sells carpet will know who sells flooring installation supplies in town.
 
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Old 10-11-00, 07:33 AM
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Maddie,

I see that you have already removed the adhesive. The reason the mastic instructions said to test to see if a bead of water stands on the concrete is because it is a test to see if the concrete has been sealed. If water beads and the concrete is sealed the mastic cannot get a good bond.

Check with your local ceramic tile supplier for what steps you need to take to prep the floor or if they have a mastic that will work in this instance.
 
  #5  
Old 10-11-00, 09:39 AM
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Hi Maddie,

All right, so you've removed everything from the concrete, but water still beads up on the surface. When installing your tile, instead of mastic, use a high-powered thin set mortar. This is the stuff that costs $20 to $30 per bag instead of five or ten. Often the brand name or description contains the term "flex." Some of these products are purported to bond to glass. Can't beat that.

Check us out at http://www.johnbridge.com

John
 
 

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