I have been chemically stripping the old latex based PPG stain off of my front porch in order to stain the floor with H&C 's solvent based concrete stain. PPG called the old coating stain but it really just seems like paint and sits on the surface and peels and lifts very easily and just doesn't hold up.

With some help and direction from "marksr" in an earlier thread I think I'm on the right course now with the correct products.

I've spent numerous hours over the last four days removing the old product off my porch floor using a combination of Franmar's Soy-Gel stripper, a razor scraper and a power washer. Labor intensive but works very well.

It looks very good but before I etch and stain I want to be absolutely sure there is no sealer on the concrete. I can tell on most of it by look and feel there isn't any but there are a couple of spots that are darker and quite smooth that I'm concerned with. I'm hoping the darker smooth areas are simply areas where the floor was highly polished mechanically when it was installed 40 years ago.

I have read about the water test to see if a few drop of water soak into the floor after a few minutes but I wonder if there is another more conclusive way to test for the presence of sealer because I've heard that highly troweled concrete can be much less porous and can give the impression of being sealed.

So my question is what other method(s) can I use to confirm it is not sealed?

Thank you

Dom

 

How about some pictures of those dark spots?

 

Normally old concrete doesn't need to be acid washed but it's possible those areas might need to be cleaned with muratic acid - it opens the pores of the slick concrete. I wouldn't think there would be any sealer left after all the cleaning and PWing you've done.

 

Pulpo and marksr, I've attached some photos of the areas of my front porch concrete floor that are dark. What does it look like to you?

Btw, I read someplace that if I put an etching solution on a sealed area it will not bubble? Do you know if this is true?

Thanks for your help and input.

Dom

 

Can't say for sure about the sealer but what you see is a slick finish not a sealer over regular finish. I'd wash it with muratic acid to be on the safe side.

 

Yesterday I etched with H&C Etching solution the smoother darker section of the concrete porch floor that I attached pictures of in my last post.

After scrubbing it and power washing off the residue that section lightened up and feels like fine sandpaper though its not as rough as 120 grit which all the etching instructions suggest you try to achieve.

So I have a few questions:

1. Any reason I can't re-etch the floor a second or third time to achieve the desired roughness before staining?

2. When doing the water test to see if there is sealer present, how much water should I put on a spot to see if it penetrates into the concrete?

3. How much time should I allow to see if the water will soak into the concrete to demonstrate there's no sealer?


I'm sorry for all the questions but I just don't want to screw this up since I've invested a lot of time and money in this project.

Thank you

Dom

 

Repeating the etching process may not be needed but shouldn't hurt anything if you do.
Water should bead over the sealer. Not sure what the time period would be a lot depends on weather conditions along with how much water is used. You need to be able to tell the difference between evaporation and absorption.