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Community and Q&A

Acid stain for concrete interior floor

adkgreen | Posted in Green Products and Materials on

We are looking to stain our new concrete (interior) slab. We have all ready added a pigment to it, so we don’t want to cover it with something opaque. I love the look of the acid stains. I have a dozen or so 12X12″ blocks from the same pour of concrete to experiment with colors.

We had a friend apply a few colors of Soy based stain and it came out very opaque, basically covering the pigment we added to the concrete. On their web page they say the soy stain in semi-transparent, while the acid stains say they are translucent.

Does anyone have experience with one or both of these types of stains? What do you like or dislike about working with them? Can you thin the soy based stain so it is less opaque and still get good results?

I can’t find information about how toxic acid stain really is. Some say the acid stain isn’t really toxic, but the sealer is.

Any thoughts?

Thank you!

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    We've used Kemiko stains and they work well on concrete but turn all adjacent woodwork black even when protected with taped 6 mil poly. and the fumes are a bit harsh during the spray application but clear up very quickly. we spray the first coat with one color and the second with another to get a varied effect that enhances the depth. I've had trouble with applying their wax finish and also have worked with Cyrene and Buckeye and now am speccing BASF's Ecoseal 40 (Water borne, low odor, squeegee applied rather than spray, 12 hour cure time)

    It's okay if you really have to have a stained concrete floor but I really prefer a tile finish, stained concrete is just too likely to be imperfect and lead to unhappy customers in my experience. Hard to protect the finished floor while a crew builds a house on it, too many things that can, and have, gone wrong. (dropped hammers, panel adhesive, walls with nails sticking out dragged across fresh concrete, nail gun oil tipped over, debris and solvents trapped under protective tarps for weeks, tile sealer in the shower tipped over on the master bathroom floor, cracks, spalling from color-hardeners misapplied, I like tile and slate too much to bother with stained concrete these days.

  2. PFhRXi6pe6 | | #2

    I have also used Kemiko stains several times in the past with great results. As Michael stated, if the wood trim is already in place you will need to protect it with some poly and tape, paying close attention to the taping to be sure the stain does not get through. Based upon the data sheet on Kemiko's website there Stone Tone Stain is low odor, 0 VOC and meets LEED requirements.

    I'm not sure how it will react with the pigmented concrete but it works great on bare concrete.

  3. kevin_in_denver | | #3

    If you added a pretty dark pigment to the mix, then the stain won't show up. The stain always takes light gray concrete and makes it darker, even the yellow stains.

    Diamond grinding can be done right before staining. That will make it stain more uniformly and expose the rocks and pebbles, making it look like terazzo. Grinding solves all the damage issues except for oil, which soaks in too deep.

    For my next project, I'm going to stain and seal before I start to build the house. The sealer will protect against everything including oil. Then hope for dry weather during dry-in, then cover with 1/8" plywood. All that's worth doing because it just has more sizzle than tile and is cheaper, even with all the extra work.

    Note that repairs won't take the stain like the original pour. Consider using Bondo instead of portland cement for repairs of gouges.

  4. adkgreen | | #4

    Thanks for the responses so far! We added a light to medium pigment to the concrete, a tannish-green. Maybe diamond grinding and sealer will make it pop and add some interest without staining.

    The house is almost complete. So far, very little apparent damage to the concrete floor. I have not looked at Kemiko stain, will do that. We have samples of Soy Crete, but my contractor has never used it.

  5. kevin_in_denver | | #5

    Basic polyurethane floor finish looks by far the best as a final coat, but cannot be used with slab on grade, only slab on joists. And it doesn't matter how much polyethylene sheeting or XPS insulation under the slab, the water vapor from the ground finds its way up in a year and pops the finish.

    That's what happened at

  6. BobHr | | #6

    If you decide to grind the concrete I would be concerned with concrete dust. Drywall dust and concrete dust are 2 of the finest dusts you have in a house. Furnace filters will not remove it from the air. It will line your duct work and you will have a white dust on your furniture for 5 to 10 years. Your family will also be breathing it for that long.

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