Black Mastic

[Marvelsaws]

My home was built in 1964 with hardwood floors throughout. Upon removing the tile from the bathroom I found what I thought was "tar paper" stuck to the hardwood. People told me later that it is commonly called "black maime" or "black mastic".

I have tried using a heat gun, a floor sander, and water. This junk will not come off!! Any chemical suggestions?

I have tried to attached a picture, the floor sander removed some of it in the threshold (I don't have a current pic). (But I see itdidn't work )

Thank you

[SSN596]

It could be that they put down 15 pound felt paper over an asphalt adhesive. Most of this can be removed with a sharp 4" or 6" wall scraper. Be prepared for frequent blade changes; get a good set of knee pads : it is a tedious job. This can also be removed with mineral spirits: DANGEROUS: flammable; turn off all pilots and have all the doors and window open. Jasco also makes adhesive removers. Not as flammable, but you need an organic vapor respirator; send the wife and kids shopping for the day while you do this.

[Avg Bear]

is this what I've got here? an asphalt adhesive?

[Marvelsaws]

Whoah!!! That's what I'm dealing with. It's called black mastic, or black mamie. Mine does appear to be put on with felt paper. Very tough stuff. Looks like you have some pretty hardwood under there trying to peek out. I've spent about $50 on various chemicals (including mineral spirits)and several hours trying to remove it. I'm at the end of my patience with it, the floor is coming out! I am just a single gal, I don't have the time nor the elbow grease so just I bought some hardwood from an old house that is being torn down and starting over. I figured it would be easier for me to tear out the floor and pay someone to just install the replacement.

Good luck to you

[kactuskid]

This black adhesive is called cutback and it's highly likely that it contains asbestos. A lab sample would confirm this. I would suggest you do not try to remove it as any sanding/scraping will allow the asbestos to become airborn which can then be dangerous. I would suggest to just install a piece of 1/4" underlayment over the top of the cutback and then install a vinyl flooring over this. Reason being is cause hardwood flooring in a bathroom is not a good idea, it's too wet and can damage the wood. Probably why the tile was laid over the existing flooring to begin with.