Being in the decorative concrete business, I've had to remove black glue from concrete floors many times.
When someone asks me to stain or epoxy their basement floor that was covered with tile or carpet, there's always black mastic or yellow glue adhesive to remove.
I'll be honest with you, there's nothing easy about removing black or yellow glue from concrete. Sometimes you can scrape most of it off with razor scrapers, but I would never say it was easy.
If you do have black glue on your concrete floor and you don't know how old it is, it could contain asbestos. Most vinyl tile flooring installed in the 60's, 70's and early 80's had asbestos in both the glue and the tiles.
Call an asbestos abatement company and get the glue & tiles tested if you're unsure, you don't want to create dust by scraping or grinding then breathe in the particles.
As long as the glue is wet and you don't create dust, you can remove this stuff. You'll just need to find out where you can dispose of it legally.
We use floor razor scrapers to remove the tiles, carpet, and the black glue on the concrete. The handle is long enough so you get good leverage to scrape with.
Make sure you get plenty of extra razor blades, they get dull fairly quickly.
We always start with these first when we remove adhesives from concrete.
Scrape off as much as you can. It's hit or miss with these. Sometimes you can remove most of the glue this way and sometimes not much at all.
Once you get a small area scraped clean, keep scraping from the cleaner spot into the glue.
This method helps you get the razor blade under the glue and lift it off the concrete.
Again, if you're unsure how old the black mastic is, make sure it's wet when you scrape it.
After you've scraped as much off as you can, you can try hot, boiling water to soften the glue.
Pour the hot water on the floor and let it sit for a couple minutes. When (or if) the adhesive becomes soft, scrape it again to remove what's left.
Spread some kitty litter on the floor to help soak up the black liquid glue. Then you can pick it up with a broom and dust pan to dispose of it.
If scraping and hot water doesn't work, another way we remove the black glue from concrete floors is with a citrus based cleaner.
In the video below, Johnny Gallegos is using a cleaner that is purely citrus based. He mops it on, gives it some time to break down the adhesive, then squeegees it off.
You can use a wet/dry vac to pick up the liquid residue or you can spread some kitty litter on the floor let it soak into that, then use a flat shovel and put it in a bucket.
The citrus cleaner he's using is D-limonene.
D-limonene is a by-product of the citrus juice industry.
It's the major component of the oil extracted from the rinds of citrus fruits.
D-limonene is much safer to use than solvent based cleaners. It's biodegradable but is classified as a slight skin irritant, so wear some gloves when using it.
See how it works removing black glue from concrete below.
As you can see in the video, the d-limonene citrus cleaner re-emulsifies the black glue. Now you can squeegee it and vacuum it off the surface.
Once all the black glue is gone, you will need to wash the floor and rinse it again to make sure any leftover residue is gone.
If all else fails, there is a black mastic remover called Bean-e-doo mastic and adhesive remover for concrete surfaces.
It's now owned by Franmar and sold under the name Blue Bear. They also have another version called 500MR mastic remover. Both products are virtually the same.
They are made from soybeans so they have almost no odor and are very safe to use.
Here's a few videos showing you how to use this product and how good it works for removing black mastic glue.
If you decide to use this product, don't forget to get their 700DG cleaner and degreaser. (formally called Emerge)
The video below is from Franmar and is showing you how to use the 500MR mastic remover to remove yellow linoleum glue.
This video below is showing you how to remove yellow carpet glue adhesive using Bean-e-doo (Blue Bear) mastic remover.
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