Concrete Countertop Acid Stain Problem

AHS

I'm putting concrete countertops in my house & am having a problem with water marks & stains showing through. I made forms right on the cabinets & poured the concrete with cabinets in place in my kitchen. I let the concrete cure for 28 days. Lightly sanded (dry) with 320 grit paper & cleaned it with a concrete cleaner. I applied 2 coats of 50/50 water & black acid stain. When I stained the concrete you could see perfect squares where I had paperwork sitting & water drips around the sink,water rings where a cup was sitting. I should have done a better job protecting the concrete until it was stained & sealed.
Could I bleach out the marks or dry sand with a heavier grit to get rid of the marks?

6stringmason

I would suggest sanding it off. Acid stain doesnt normally penetrate real deep. You may start to expose a bit of the fines in the concrete, but you should still get the marks out and be able to reapply the stain with decent results.

Dont start sanding at too much of a low grit. If you have diamond pads I would suggest maybe start at 800 and see what that does for you.

What are you using to seal the concrete? If you're not using anything you will still get stains no matter what.

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Kamps Masonry & Concrete Countertop Design Green Bay, WI
920-680-3195
Visit our website @
http://www.concretecountertopsdesign.com/

AHS

I'm using the buddy rhodes sealer once I get the look right. One place I talked to recommended I start at a 50 grit diamond pad & work my way to 3000. What would happen if I went in & sanded with the 50 grit? Just make more work for myself to sand it back even or would it ruin the surface?

Tscarborough

You will expose aggregate if you use 50 grit.

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It ain't Rocket Science unless you are building rockets.

6stringmason

Trust me... start with 800 and work your way DOWN as neede. Do NOT start with a 50.

Tscar is right. You will expose aggragrate with a 50, 100, 200, and possibly a 300. Depending on pressure applied.

Once you expose aggragrate kiss acid staining good bye.

__________________
Kamps Masonry & Concrete Countertop Design Green Bay, WI
920-680-3195
Visit our website @
http://www.concretecountertopsdesign.com/

L.A.C.I.

Very nice. Just joined the club and wanted to introduce myself. Didn't mean to interrupt so Brut.

kongcrete

First off you should never have waited 28 days. This whole 28 day thing with concrete gets thrown around too much and everyone just uses that number by default for everything. Its more of an issue with slabs on grade but even then I dont wait 28 days before staining and sealing. If you didnt wait that long you would have never had these issues.

Like the other guys said you are going to have to sand (or grind if the stains are deep) to get rid of them. You can still stain the concrete if you expose the aggregate, you just wont get that nice marbelized look. I actually have ground and exposed concrete countertops in my house acid stained a moss color.

I would grind/polish with a 2-400 grit diamond pad to get rid of your stains (800 grit aint gonna do it unless your concrete is real soft) then stain and seal with a solvent sealer. Then either wet sand by hand or use a 7" #0 steel wool on a 7" polisher to smooth out any little knicks and things in the sealer, then high speed buff with a lambs wool attachment on a 7" polisher. This is what we do and it works really nice for our acid stained counters.

AHS

When you acid stain do you dampen the surface first. I have 2 similar size slabs that I acid stained, 1 of them came out awesome with interesting looking variations in the color & the other one was a lot more bland looking & didn't have nearly the amount of variation. The only difference in the way I preped the area is I stained the one slab while it was still a little damp & the other one was completley dry.

http://i263.photobucket.com/albums/i...oncrete046.jpg

http://i263.photobucket.com/albums/i...oncrete047.jpg

amasonbygrace

I have never used acid stains so I'm afraid I can't help you w/ any advice. However I,myself, could use some. I sold a concrete bar top to a customer nearly one year ago. She called and said that she was getting water marks on it. It hasn't been re-beeswaxed or sealed for that time. What suggestions would you all make to solve this problem and what kind of responsibility do you all feel I should take in this matter?. We did tell her of the regular maintainance required for concrete countertops when we sold them to her. I'm not completely sure, but I'm assuming that glasses w/ ice are left setting on the bar until the next day. I'm open to all educated suggestions. Thank you

6stringmason

I would say as long as you told her of the problems, you are not responsible.

Too fix it, if you're willing, I guess depends on the color and finish. It may be possible to light grind on the piece to remove the marks, then reseal and wax.

I posted a thread to find out how you guys who dont use an epoxy type sealer deal with this and tell customers what to expect. Im still waiting to hear answers.

What sealer did you use for this?

__________________
Kamps Masonry & Concrete Countertop Design Green Bay, WI
920-680-3195
Visit our website @
http://www.concretecountertopsdesign.com/

genecarp

densefier, next time, unfortunately concrete tops dont repair easily, if you sand again and bring it to a high polish, you will not get a good stain result, pours will close, additionally the top surface of a fresh top is where the interesting staining happens, the cream that was brought up while troweling has the properties that the stain reacts to.

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amasonbygrace

ty so much sixstringmason for your advice, I will try and do some light grinding and repolishing. I will tell her b4 hand that it may not solve the problem or may run the risk of not fixing it either. We used a penetrating sealer, not sure of the brand name. Only set of tops that we've actually sold so far, new market area, finding it hard to sell people on them. Thank you again for the advice.

ConcreteKenny

Ameripolish makes a great dye. you may have to strip the sealer first. I went to a bob harris training in vegas and he showed us how to use these dyes as a touch up for acid staining. There are always issues with acid staining. In the future it's better to simulate these acid staining with dyes. I think I am done with the acids.

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Steve
Stamped Concrete Concrete Concrete Orange County Polished Concrete Polished Concrete Contractor