Self Leveling Over Black Mastic/cutbacks

self-leveling over black mastic/cutbacks

Are you attempting to level your home’s flooring with black mastic on the floor? If so, this will prevent the self-leveling compound from adhering correctly to the flooring, which can lead to issues once the self-leveling is finished.

black mastic

Tile adhesive causes black mastic on the subfloor, and you can see this when you remove the floor coverings like vinyl tiles, carpets, and ceramic tiles. The adhesive that has been used to glue the floor topping to the subfloor changes color over time. And it can pop out the black color on the surface of the flooring. 

The old houses that were built in the 1980s that have tiles as flooringhadr tile adhesive containing asbestos, which is very harmful. It was widely used because it was cheap and served its purpose well.

When the problems began, the old building that had these tiles was about to be resurfaced.

After removing the tile from the floor, it was found that the floor surface had harmful black mastic.

Self-leveling over black mastic containing asbestos

When trying to self-level concrete that has this hazardous asbestos, there are two methods of doing it.

The first method is to remove the black mastic, then seal and self-level.

The second method is to seal the floor and self-leveling without removing the black mastic. 

Removing the black mastic with asbestos

Removing black mastic that contains asbestos is something that I recommend calling in an expert for because of the harmful nature of asbestos. But if you decide to do it by yourself, you must be careful. Here are the steps that you can follow to remove the black mastic

Examination of the floor of asbestos

Check to see if the underside of fractured tiles is black or dark gray.
Check the tiles on your floor to see if there are any black stains.
Check your array of square tiles to see whether any are 9 by 9 in (230 by 230 mm) or larger.
Find out whether your house was constructed before 1980.

Materials for removing black mastic

Mastic and glue remover

Scrubbing pad

Oil cleaner/degreaser


Getting the right equipment and protective devices

1. 9″ roller with a very thick nap 

2. 10-inch Scrape Spatula, Drywall TAPI

3. Small scraper for edges around walls

4. Large container with a plastic liner to dispose of glue

5. Knee Pads 

6. Wear shoe guards, old disposable shoes, or spike shoes

7. Disposable stringy mop

8. 20-inch green Scrubbing Pad or stiff plastic bristle brush

9. 20-inch surface maintainer

10. A bucket to wash the floor

11. Wet/dry shop vacuum 

Steps to removing the black mastic/cutback adhesive

  1. Cover the wall area that is close to the floor so that the black mastic will not spill on the wall.
  2. Pour the mastic remover directly on the floor, either with a pump sprayer or
  3. Use the squeegee and the brush to spread and make the floor soak as much as possible, then let it wait for 15 minutes.
  4. At this moment the black mastic is now easy to remove, carefully use the scraper to remove the mastic, moving in a vertical and horizontal pattern.
  5. After scraping the cutback adhesive, then using the squeegee bring the cutback adhesive together and pour the black mastic absorber on it, and when it absorbs the wet black mastic, then you shovel it into a disposable bag for proper dispose
  6. Wash the floor properly with TCP or any asphalt residual chemical mixed with hot water to remove the remains of the black mastic.
  7. After 24 hours of total work, the floor is ready for another re-flooring.

how to Seal black mastic/Cutback adhesives

When it comes to the sealing of the black mastic or cutback, it is the application of Perfect Primer over the black mastic. This method can be applied to any subfloor that has cutbacks, carpet glue, or black mastic. In my research, I have only found one company that has the primer for sealing the cutbacks, and athat isPerfect Primer. Here are the steps to carry out this sealing:

  • Grind down the surface of cutbacks to remove the loose debris and also reduce the level of glue on the floor.
  • Apply one coat of Perfect Primer on the subfloor; this will cover the black mastic, and it will not be visible. The next flooring will not be affected by Cutback Adhesive

What is a black Mastic? 

Mastic is a synthetic flooring adhesive that looks like black glue and produces strong skin on flooring materials like vinyl.

Asbestos was formerly present in black mastic materials used to cover vinyl and linoleum in the twentieth century.

Black mastic is a substance that might be dangerous. This is due to the fact that a large variety of black mastic materials include asbestos, a hazardous substance known to cause the deadly ailment of mesothelioma. 

How to detect the presence of black mastic

If you discover that the aforementioned is present on that floor, you can either hire a professional to verify it or get the testing equipment and carry it out on your own.

Other ways to remove black mastic

There are three methods for removing black mastic.

  • Using floor machines
  • Non-chemical removal
  • Chemical removal 

Be aware that you will require both working and protection tools for this task, or you will want to hire a professional.

Use of Floor Machine

The grinding machine is also a tool to remove black mastic, cutback, and carpet glue from the floor. The grinder must be attached to a black mastic remover plate.

In this method, one has to be careful because sometimes the grinder can get heated up, which will lead to the machine breaking down because black mastic or cutback adhesive is difficult to remove.

Another thing to note when using the grinder is if the house was built in the 1980s, and it is suspected that the tile and carpet adhesive contain asbestos. Please do not grind.

Caution for removing black mastic

Contractors or individuals who are carrying out the removal job must maintain the black mastic damp during removal in order to lower the possibility of airborne particle release.
In addition to wearing a respirator, construction workers are required by this material to be provided with other safety gear such as goggles, protective coats, and rubber boots.

Can you self-level an epoxy over a black mastic?

It is possible to put epoxy flooring over black mastic, prior to the floor being sealed properly with a primer that is able to override the black mastic color.


In general, when dealing with black mastic, carpet glue, or cutback adhesive, you have to be careful first and have the right knowledge before self-leveling over them. Because these things can really be a lot of trouble when you do not get them right.