How to remove black mastic from hardwood floor?

falineJanuary 26, 2011

We're fixing up an older house in preparation for moving. After taking up the filthy carpet, we discovered that underneath are hardwood floors in 2 rooms which are covered with tile and black mastic. (I guess that's what it is?) How do I get the mastic or adhesive--whatever it is-- off without damaging the hardwood? (And yes, I'm aware of asbestos, it wasn't tested but we're taking proper precautions.)

I read online that boiling water will do it, but what would that do to the hardwood? Or do I need a citrus solvent (if so, brand recommendations?) or something else?

I really would like to save the hardwood if possible. I don't mind the rustic look and good thing because I can't refinish the floors right away.

Any tried and true advice would be MUCH appreciated. We're not living in the house yet but will be working there this weekend.

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glennsfc

The adhesive may emulsify in the presence of hot water. If it is a hydrocarbon type, then the water will have no effect.

Be aware that any solvent you may use in your attempt to soften the adhesive will drive the adhesive deeper into the wood fibers.

    Bookmark   January 26, 2011 at 11:22AM
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patser

Use mineral spirits to soften the mastic and scrape off all that you can. You should be able to get enough off to then be able to sand the floors. That's when the asbestos concerns come into play.

Mineral spirits won't drive it into the grain.

    Bookmark   January 26, 2011 at 11:43AM
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brickeyee

"Mineral spirits won't drive it into the grain."

Mineral spirits will easily carry the color deeper into the wood.

    Bookmark   January 26, 2011 at 3:20PM
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patser

What's your suggested solution, brickeyee?

    Bookmark   January 27, 2011 at 6:08AM
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glennsfc

While we wait for brickeye's response, a solvent will drive the adhesive residue deeper into the wood, which will require a deeper sanding to get beneath the resulting stain.

Best way to handle this is to hire a professional who can remove this for you. If you insist on DIY, then slice off all you can with a sharp razor scraper and then be prepared to sand the rest of it off.

    Bookmark   January 27, 2011 at 5:23PM
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aliceinwonderland_id

If you have access to dry ice and good, thick gloves to protect your hands - you can place the dry ice on a small area of the mastic at a time to freeze it, then rap with a hammer to shatter the mastic, sweep it up, move on to the next spot. You will still have to use sand or use solvent to remove whatever remains.

    Bookmark   January 28, 2011 at 11:56AM
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brickeyee

You need to have the mastic checked for asbestos content before trying dry removal methods.

Dry ice works sometimes, or just heavy sanding with a drum sander (and a lot of paper).

If you use anything liquid the material can move deeper into the wood, and WILL move into the cracks between the boards.

When you then sand the edges of every board can show staining.

    Bookmark   January 29, 2011 at 11:13AM
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woodfloorpro

Finishing with any traditional solvent based stain or urethane will wick out remaining mastic from between the boards. I would only sand it or scrap it off.

    Bookmark   January 29, 2011 at 11:46AM
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