Carpeting and tile glued to a concrete floor can usually be pulled up easily, but removing the dried latex mastic (glue) that remains is a labor-intensive, challenging, and potentially dangerous job. Getting the mastic off is a multiple-step process.
Step 1
Read this over, then decide if you have the time, physical health, and desire to start the job. For some people, hiring out the job is a better choice.
Step 2
If the area covered with dried mastic is greater than 25-30 sq ft, or if the area is in an enclosed area that cannot be well-ventilated, seriously consider hiring out the job.
Step 3
How much must you remove? If you want the mastic completely removed, 100% gone, understand that under normal circumstances that cannot be accomplished. Some mastic will have filled small voids in the surface of the cement and will always be visible. However, if you get to that stage, then the surface will probably be very close to perfectly smooth, and with acid etching it will satisfactorily accept a concrete paint or "stain" .
Step 4
Pull up the carpeting or tile, and scrape the mastic-impregnated surface with a flatnose shovel.
Step 5
Next try a one-inch or smaller wood chisel.
Step 6
Next try a razor-blade paint remover, the kind used for window glass.
Step 7
What remains is best treated with chemicals.
Step 8
Put a golf-ball-sized glob of commercial latex mastic remover on a 4 x 4-in spot and wait 10 minutes. It will show signs of dissolving. With a putty knife, scrape up the softened mess and discard. You won't get the mastic all off in one pass. Repeat two or three times using the chemical remover.
Step 9
When you've cleaned off about all you can with the chemical, you can remove the haze of mastic left by wiping down small areas with lacquer thinner. It works well, but it is pricey, and without excellent ventilation it will kill brain cells.
Step 10
Remove the stubborn, small patches of mastic remaining by rubbing them off with a pumice stone, such as those sold in swimming pool materials departments of building supply stores.
Step 11
The distressed look of the smooth surface might not be acceptable, but the surface can be easily acid washed and painted. Solutions for acid washing are widely available, and if the worker wears proper protection for the eyes, hands, arms, and feet it goes quickly.
Step 12
Semi-transparent concrete paint or "stain" is easily sprayed over the cleaned and etched concrete surface using a gardener's pump sprayer. This follow with a commercial, clear sealer makes an very acceptable finish.
Tips
- Note that these will not soften or remove mastic: the force of 120 psi water pressure washer; alcohol; cooking oil; detergent; boiling water (unless you have unlimited access to gallons per minute.); paint thinner; acid; lye; a 2-3/4-in wide, iron scrapper with shovel-like handle sold for removing vinyl flooring (the width of its blade is too wide to allow a person of normal strength to use it in removing mastic.)
- Brute force goes only so far. You will have to use chemicals.
- There are now companies that make non-toxic mastic removers that do a great job dissolving the mastic without killing your brain cells. One example is Bean-e-doo.
- If your home was built around the 70s or so and you've removed vinyl tiles and the mastic is black and hardened - you can spray WD40 on the areas and it will re-emulsify the adhesive turning it into what looks like motor oil. Scrape the mastic into a pile and apply a commercial absorbent - you can then sweep the material. This takes several applications, but does work.
Warnings
- Volatile hydrocarbons are hazardous to health. Ventilate well. Remember that fumes from most hydrocarbons are heavier than air and may accumulate at volatile concentrations close to the floor. All potential ignition sources should be removed from the work area and adjacent rooms. These include: furnaces, hot water heaters and electrical appliances. Tragic consequences have occurred from misuse of solvents in the home.
