Cutback remove and acid stain subfloor

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leaf's picture

Hi.  Great forum!  I find at the other floor forums the pros seem to lack experience and mastery when it comes to decorative concrete so the answers are all over the map and vague.  Anyway, ideally I'd like to acid stain my subfloor.  Even though I just spent over 40 hours scraping cutback adhesive (with asbestos) down to the residue I thought I could get it all up with a chemical remover and acid stain what's left.  This would save a lot of money because I wouldn't have to prime and put down a microtopping (like Skraffino from Duraamen). Also, I like the irregularities/damage to the subfloor and think it would look good acid stained.  My question is, since my subfloor has a good bit of irregularities like scarring and peeling and damage, the cutback adhesive is wedged into a lot of little nooks and crannies that I couldn't get to by scraping.  Will the adhesive remover be able to get this up?  Can I get my floor totally clean free of stains?


After cleaning the adhesive remover, I would plan on using Mapei's Planiprep SA followed by the Planiprep ET in order to, as they say, seal off the concrete to prevent any leaching up of the solvent used to clean off the adhesive remover.  Or maybe I should use the Planiprep ET after the acid stain.  I'll aske Mapei.  When I saw this about the ET I thought, "Wow, if this works people can stop wet scraping."  So does anyone know?  Does the Planiprep ET work?  Do I even need it in order to acid stain and seal the slab.  I know the resilient flooring institute says to wet scrape but I'm not planning on putting anything on top of the slab except an acid stain and sealer.


Lindy A.'s picture
Lindy A.
I have no insight on the

I have no insight on the Mapei Planiprep SA or ET ... have never used them; although I have applied Mapai's self-leveling micro-topping/Ultratop that provides a level, smooth, virgin cementitous substrate that assures uniform mottled acid stain reaction. 

You will NOT obtain a uniform acid stain reaction on concrete that has ANY type of foreign matter that is lingering down in the pores of the concrete or on the concrete slab surface, it will prevent the acid stain from reacting (due to all the issues you described); I understand that this is not what you want to hear (or an additoinal cost/investment in your proposed project), but IMO professional opinion you should really consider applying Mapai's self-leveling microtopping (viable alternatives include: Rapid Set Tru self-leveing, Ardex STC, or equal to these), then acid staining and sealing it.  A skilled applicator can camoflauge spots/areas that the acid stain does not react on concrete (due to foreign matter that remains after surface prep that impedes it from doing so as in your particular case will be a factor) using concrete dyes to touch up and blend them in (this is tedious, especially if this in much more than a random few spots, but with experience it can be done). 

Please take all this into consideration before jumping off, putting your labor and money into this floor, only for the outcome to be less than decorative/satisfactory (of course, beauty is in the eye of the beholder, it's just that some peoples idea of "good enough" is far less than a decorative floor of beauty in mine and others that seek the ultimate in vibrant/designer edge beauty, longevity, performance, and perfection.


leaf's picture
sound advice

Thanks for the insight.  The more I thought about it, the more I began to think there was no way of totally cleaning the floor for an acid stain so your advice is not a shocker.  The Ultratop data sheet said to thoroughly clean adhesive residue and all foreign substances.  This makes me think it wasn't designed to go over cutback adhesive residue.  It also says to always prime with Planibond EBA and it's data sheet said the same thing.  In contrast, Primer T is made to go over cutback adhesive residue that has a strong bond to the substrate.  However, it needs a self-leveling underlayment to go on top of it apparently.  I'm trying to talk to Mapei about the possibility of putting a trowelable microtopping over it but I can't get ahold of anyone either on the phone or via e-mail.  


I thought of ardex feather finish and then their sd-m but they said there's a possibility that the cutback residue could bleed through over time and discolor the finished floor.  Can you explain how I can test to see if this will or will not happen.  I read somewhere that theres a way to predict this.  I don't think my cutback is very volitile (not sure if that's the correct word) and it's an extremely thin layer.  They said Ardex FF wasn't strong enough to be a wearable layer yet it's compression strength is the same as other top layers that other companies sell (like Skraffino from Duraamen).  Does the Ardex FF have trouble getting sealed properly or is it too crumbly....


Anyway, Skraffino from Duraamen seems like the best option so far.  I like it because it's just primer then microtopping and both were designed to go over cutback.  My only hang up is that I've only been able to talk to one person and he seems like he really wants to make this sale to get a commission.  He's just been pushy and car-saleman like.  I'd like a second opinion from an uninvolved party.  


I wonder how many coats are needed.  I just want to encapsulate the cutback and provide a surface suitable for walking on that I can acid stain.  Can I get away with one coat of microtopping that has a psi of 4200?  I would like to maintain the irregularities in the concrete plus it would save a lot of money just going with one coat at about 1/32 of an inch thick.  At the same time, like you said, I'd like to do it right so that I can have the confidence that it will last forever.  However, and Ardex K15, for example, is overkill as it is strong enough to drive a fork lift over.  


If it starts getting up in the $2 a foot range I'll start thinking of the bamboo flooring that goes for $2 a foot.

Lindy A.'s picture
Lindy A.
IMO personal opinion I think

IMO personal opinion I think you should consider "Perfect Primer" maufactured by Specialty Solutions (New Hyde, NY); I know the owner/formulator personally and will attest to this being a viable solution (going back to early 2000's).  Perfect Primer can (and has a proven record) of being successfully applied over mastic, cut back, sealed concrete, VCT, ceramic tile, and several other compatible substrates/composites.  It is environmentally safe, applicator friendly, solvent free, and drys quickly.  You can then apply various types of resurfacing sytems successfully over it such as acrylic/polymer modified cementitious overlayments and micro- toppings (which you could integrally color, acid stain, etc), industrial flooring/epoxy systems (seamless flake/chips or colorquartz), etc. ... if you want to drop me an email:  I will forward you more detailed information in regards to the entire scope of your project based on real world/30+ years hands-on experience/expertise (unbiased, no horse in the race).

All the above you have been considering, along with your questions/concerns and formulating of a viable game/concrete resurafcing plan, are making me dizzy just trying to keep up with your thought/consideration and issues process. The word "simplify" needs to be added in order to proceed down the road in the easist, highest performing, and end result direction.


thanks for the whole

thanks for the whole conversation! i am also going through kind of a same situation, but after reading all this. i dont think it would be a problem anymore.!

leaf's picture
Hi Lindy and whoever else, I

Hi Lindy and whoever else,

I just wanted to touch base one more time over here before going ahead with my plan because I'm wondering if some of the floor should get primer for porous substrate.  I've attached a few pics of my floor to give you an idea.  As you will see, there is quite a large portion that does not have any cutback or anything on it.  I got Ardex P82 Ultraprime primer for non-porous substrates and I'm getting ready to coat the floor in that.  (I went with the P82 because it's half the price of the Perfect Prime).  Should I hold up and get P51 for absorbant substrates and then sort of hand paint it onto the larger areas that don't have cutback that you see in the photos?  It should be noted that when I put a tablespoon of water on the porous patches, the water does NOT absorb into the concrete oddly enough.  So this means it non-absorbent right?  I've been told that by default, it's porous but that maybe it's very tight so that is the reason that it doesn't absorb water.  Am I worrying too much about this?

leaf's picture
Sorry, the photo size was out

Sorry, the photo size was out of wack.  HEre's some resized ones.  The white spots are the places where there is no cutback adhesive.  It's just the original slab that was layed down.  And don't worry, it's not crumbling or anything there.  I've scraped all the loose stuff off so it's all solid.