April 5, 2011

Sepia concrete and black mastic

We have: 2,500 sqft of dusty concrete floor on which tiles were at some point glued and then removed, leaving a lot of old black mastic behind, of various thickness and patterns. We have: a mess of a floor.

We want: a beautiful floor that costs us nothing! Or close to nothing. So we're keeping the concrete floor. No carpet, no laminate, no linoleum, no tiles. We're going to simply polish it. But what do we do about the mastic?

Either: scrape off all of the mastic. Backbreaking, tedious, time-consuming. But maybe necessary. Then seal the concrete floor. Done. But then we have a uniform floor. Is that too boring?

Or: leave the mastic be and just seal the floor since we actually really like the texture of the floor as it is now. But it might be too much with the rafters which are already painted black. I would love to strip those beams back to the original wood but it would be an insensible amount of work. If this were my house I would put in the time and money, but this is not my house. So the beams stay black. How do we feel about a black floor and a black ceiling? Can we make it work?

Or: leave the mastic, but apply a coat of semi-transparent light gray stain before sealing, for a sort of blurrier Julie Mehretu kind of look, where the texture of black and sepia would show beneath a layer of slighty milky resin. Question is: how is the mastic going to react to the stain? If the mastic is oil-based (and it probably is) do we have to use an oil-based stain? Will an acrylic top coat work? Will the mastic wear off anyway?

So many questions. Feel free to share any insight or experience you might have! We're a little in the dark on that one (no pun intended).

I guess we'll just have to do some more research and keep on doing samples. Today we simply cleaned a portion of the floor with a wet rag and applied three coats of floor polish.

What do you guys think? Love it? Hate it? Don't care?


  1. Leave the mastic and seal it---it looks beautiful!

  2. I think we're just going to scrape off the darker areas and seal it. Going to the hardware store in the morning to look for a non-glossy sealer. And maybe tint it. Maybe.

  3. I love the look above, and for a restaurant I think it will be easy to clean with a mop.

  4. My Michael says he is concerned that the mastic will soften over time and perhaps have a problem of it sticking to customer shoes, yuke! He will be thinking of solution(his past expertise is in industrial concrete w/epoxy finish's, remodeling, building houses and refinishing fine boats) you could go in w/polisher/grinder and take surface off to bring up aggregate/tarazzo....then take saw & put patterns in then stain & seal? Do you get this...it's all greek to me?!

  5. Oh yes I would love to have a personal professional opinion on the mastic issue. We had someone scrape the entire floor the other day, meaning there is still black mastic on it, but not thick patches anymore. This will probably make it seal easier, but I still think it needs to be sealed with a heavy duty, oil based, floor specific poly. What does Michael think?

  6. this has inspired me to do the same with my floors.... I just removed 40 year old 12x12 asphalt tiles and I did sand some but I LOVED the shadows of where the tiles laid along with the glue…it looks AWESOME…


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