White dust/film after etching

[desmo907]

After much research I decided to go with the Sherwin Williams Sheild Crete epoxy for my ~25 y/o garage floor. I did the water bead test and there are spots where it seems to bead, and also puddle due to low spots. So I used the SW degreaser today, scrubbed, and washed. I then used their etching solution, scrubbed and washed alot. I notice later a thin white film, almost like a dust. i can rub it with my sneaker or finger. I assume it is from the concrete that i washed many times. I did this in halves as i had so much stuff and it is a 2 1/2 car garage. I don't expect to paint for a week until the temp/humidity goes down and I'll d that in halves too (and let cure for a week or so). I am also hoping that the 4 kits (each say cover ~200-250 sf) will cover my 668 but maybe not due to the etching so suspect I should get another kit.

As far as this white film... do i just mop it up or try washing again?

BTW - my neighbor (whose home was the same builder) did his too using Rustoleum but he used muratic acid and has the same dust/film.
Both of us notice that the water doesn't actually drain through the concrete but I wonder about this "test" they have you perform to test if it had been sealed. When i etched it did cause a little foaming which the HW solution bottle says is good and means the concrete has not been sealed.

Thoughts?
Thx

 

[tunnelengineer]

You need to rent a pressure washer and really wash away the film. I rinsed my garage floor 6 times and still had it. One pass with a pressure washer and it was gone. Made a world of difference.

 

[munkey]

I had the same experience, and tunnelengineer is right: pressure washing is the only way to get rid of it. Definitely do not skip doing it. You want to make sure your coating adheres to the actual concrete and not a thin layer of concrete dust sitting on top of the concrete. (Epoxy projects are way too time consuming to risk having to redo!)

 

[AlphaGarage]

Muriatic acid works by leaching calcium out of the concrete, but it doesn't vaporize that calcium. What you're seeing is that fine calcium dust. Calcium helps the concrete stuff stick together, and now the dust is sticking to the concrete, sticking well enough that it's a pain to remove, but not adhereing that well that it will stick around for the long run. If you coat over it, the epoxy will stick to the dust, not to the underlying concrete, and when that dust does debond and lift, so will your coating.

Pressure wash it off, or acid etch again.

The way to avoid that is to not allow the acid solution to dry on the concrete, keep it wet. If it's hot weather work in smaller sections. Remember that the acid does most of it work in the first 5 - 10 minutes, at that point rinse & neutralize, rinse again.

 

[LegacyIndustrial]

Keep rinsing until it's gone. This a common issue with acid etching.

 

[Oldbear]

I had the same white powder... so I rinsed and scrubbed (with the same hard brush) a few more times while rinsing and squeeqeeing the floor - did this until it rinsed clean. I had even let it dry for an extra day - only to find the white powder. Next room may just get the acid staining treatment - seemed like more work - but it doesn't now. (I'm doing the entire basement floor by the time we're done - starting with the garage and laundry rooms).

 

[rugerlady]

The residue needs to be removed. This would be done by either pressure washing or re etching the concrete. Acid residue can act as a contaminat on the floor if left there.