My original aim was to end up with a, possibly stained, clear-coated cement floor. After removing old floor tiles, I rented a floor grinder which took care of most of the old mastic. There were still thin spots that remained, so I bought some product at HD that softened the spots for removal, but as others have said, made a friggin' nightmarish mess of it! Will the residue prevent sealers or other coatings from absorbing into the concrete floor? If so, would thinset even stick to these areas? I don't want the expense of tile, but I've about had it trying to clean up this tar-like mastic to clean and clear-coat this floor! Any suggestions? Thanks, Bill
I had an entry way floor some 30 years ago that had old hard vinyl tile glued down in it with the blackish-brown type of adhesive. I wanted to replace that tile with a ceramic floor tile so I peeled out all of the old tile. I then used a wide razor scraper to get most of the old adhesive scraped off.
After that I purchased a few gallons of aggressive paint stripper, opened every window in the house, shut off all gas appliances and pilot lights and poured out a layer of the stripper across the whole floor.
I let it sit for a suitable time (may have been about a half hour or so). Then working some with a wire brush and metal dust pan as a scoop I took up all the goop off the floor.
Finally using a bucket and a large sponge I washed up the whole area with a copious amount of hot water to remove all the stripper residue.
After the floor fully dried the surface was the nicest clean concrete surface you could wish for. I was able to put down the tile setting cement and had no problems with it adhering to the concrete.
I used bean-e-doo from Franmar mastic remover.The company was bought by "Bear".
It works like a charm and very easy to use. It's also environment friendly as it is made out of soy bean (virtually no smell). It costs about $35 a gallon. The amount to use depends on the surface and the thickness of the mastic.
I hope that helps.
clearing a concrete slab is an entirely different process than using it as a base for some other flooring the key is homogeneity.
to achieve that, on a previously adhered to floor, is to coat it with a layer of new cementious material. just trowel on 1/4" or so of a good high polymer modified levelling compound (not a self levelling compound) or a tile mortar (flextile 56 or dyna ceraflex 620 works great for this). let cure and then put down your stain/stains/topcoat. try to get a topcoat that has the aluminum oxide in it - they wear far better, but they are more money and harder to apply.
you can skip this step if the old flooring was tile or something un-adhered to the concrete, but if what was there previously used any kind of adhesive (as opposed to a mortar), you will get terrible results. the surface pores of the concrete will be irregularly sealed with the adhesive, even if you use an acid etch or a chemical stripper to remove it. thats going to give you a very blotchy and heterogeneous finish on the final coating. and if you use a topcoating paint instead of a stain, it will adhere poorly where those same residues are and wear through differently over time.
this is all assuming you want a clearcoat on top, and not just a paint. if you want just a painted floor, then just strip and paint - just use a good two component epoxy for best results.