Mastic is a resin-based adhesive obtained from the mastic tree; it is flammable, super sticky, and has a thick consistency.
So let’s look into how to remove black mastic from concrete floor. Mastic is used to attach top flooring to the subfloor underneath. It’s commonly used in the installation of carpet, vinyl, or tile to the concrete, steel, or wood subfloor.
You can remove black mastic from concrete floor by sanding, using chemical solvents, or simply chiseling off the dried adhesive; this is needed when installing new flooring, which ensures that the new floor doesn’t crack or have issues due to the dried adhesive.
You also need to take off mastic for safety reasons as they sometimes contain asbestos.
How to Remove Black Mastic from Concrete Floor
Table of Contents
- Using Hot Water
This method is only effective on certain types of mastic, especially those used in recent homes. Wet the mastic with hot water; this softens and causes the mastic to loosen within 20 to 60 minutes; this also makes other methods safer. For extra strength, you can add some vinegar or citrus degreaser to the hot water.
- Using A Chisel
Once the mastic has softened, you can use a hammer and chisel to scrape it off; you can also use a wide putty knife for this as well.
- Using A Heat Gun
If the mastic contains linseed oil, it will soften when heated. But bear in mind, these are also flammable. You will need heat-resistant gloves to protect your hands, and do not use the heat gun for more than a few seconds at a spot. Once the glue softens, scrape up with a putty knife.
You can use a chemical solvent to remove black mastic from concrete floor. There are different types of mastic removers; some are made from citrus or acetic acid and tend to be milder in action. Opt for the mastic type suitable for your flooring.
Apply a thin layer of mastic remover using a sprayer or a mop. For wood floors, apply the mastic remover using rags.
Start at the farthest end of the room and work your way toward the exit. Allow the mastic to dissolve; this can take anywhere from 1 to 12 hours, depending on the product and how thick the mastic is.
To make the cleanup easier, you can cover the mastic with cat litter, absorbing the liquid.
Using a razor scraper or putty knife, scrape up any stuck-on mastic and dispose of it properly. If working on a large area, you can use a floor machine equipped with a 3m black scrubbing pad to speed things up.
Apply another thin layer of mastic remover to remove any remaining residue. Use a mop or bristled broom to scrub it off. Use an absorbent material or rag to dry the area, or you can rent a wet vacuum for large areas.
Using A Floor Machine
This method is only suitable for mastic that does not contain asbestos, as it could cause illness or death when inhaled.
Even if the mastic does not contain asbestos, you should protect yourself from debris by wearing safety pieces of equipment like glasses, a paper mask, and work gloves.
You will need a rotary floor machine which you can rent. You can use a floor grinder for this as well, and it doesn’t require a mastic removal block.
Attach a mastic removal block to your floor machine. It usually has several blades at the base, which cuts through the mastic.
With the machine plugged in and turned on, push it slowly over the mastic and go over each area several times.
Take breaks periodically and sweep up the broken mastic. This enables you to see the areas where the mastic remains.
After using the machine to remove almost all of the mastic, apply a degreasing solution over the residue left behind. Allow it to sit for 10 minutes or as directed in the packaging label.
Opt for a degreaser suitable for your flooring type.
Next, scrub or scrape the floor with a scrubbing brush or stripping pad attached to the floor machine. Use it to remove the last pieces of mastic. You can also use a putty knife for this.
Give the floor a final cleaning with a wet vacuum with a front-attached squeegee, use it to vacuum up the broken mastic. Finish up by mopping the floor with soapy water and go over with the wet vac again.
Read: How to stop water from coming through concrete floor
Having covered how to remove black mastic from concrete floor, you should know it can be done by sanding, using chemical solvents, or by simply chiseling off the dried adhesive; it is a crucial step that needs to be carried out before installing new flooring, this ensures that the new floor doesn’t crack or have issues due to the dried adhesive.