acid etching vs. mechanical?

[sparkplugmstr]

I am ready to start the project and was wondering if the mechanical etch would be better and if anyone has done so?

The mechanical would be accomplished with a floor sander/grinder with a diamond bit.

Any thoughts???

Thanks pics coming soon!

 

[filthy_shovel]

Depends. What are you planning on doing with the slab?

 

[bmwpower]

Depends on your floor.

If your floor is pretty smooth now (no troweling marks or high spots), the you could just get away with acid etching. Acid etching is much quicker to do.

If your floor has high spots or the surface is pretty rough, you could grind the floor. You STILL need to acid etch after doing so as the acid etch is what gives the floor it's 3D profile which allows the epoxy to really stick to the floor.

I did both. I ground down a bunch of trowel marks and high spots and then acid etched.

 

[GearHead_1]

Do them both, the acid etch not only makes the surface somewhat more rough but neutralizes the alkaline nature of the concrete of course the water rinse neutralizes the acidic nature of the muratic acid. The mechanical part of this duo not only roughs up the surface but removes anything that is sitting on top of it whether it be drywall mud, paint or most anything else. Special attenion should be paid to any oil mark on the concrete as neither of these two methods specifically addresses oil.

That's what I did so it's gotta be right. Right?

 

[sparkplugmstr]

acid vs mechanical etch

Thanks for all the responces guys. I plan to use the epoxy coat product. Most of the surface is 9 mos old and no high spots or oil. The last third of the garage is the "old" garage and is only 6 years old again no high spots or oil though it has a cement sealer on it. Knowing I was covering the floor when the new garage was put down I had them not put on a sealer. It's my understanding the acid etch will remove the sealer correct??? If I just acid wash the floor should I do it more than once? Seems like some have and some haven't???

Thanks again pics soon, Sparkster

 

[bmwpower]

Acid won't remove the sealer. You'll have to grind the sealer off. You may be able to chemically remove the sealer, however, but I'd still resort to grinding the surface as this is the only way to be sure the sealer is gone.

How many times you need to etch depends again on your situation. What concentration of acid are you using? I figured I could get away with one etch (I used 1 part muriatic acid to 4 parts water on 1 year old virgin concrete), but it turned out I needed to do it twice. You should expect to possibly have to do it twice. Do it once then look at the condition of the concrete after the 1st etch. Is it uniformly etched? Do some spots remain unetched? My concrete had a decent amount of "cream" on top. The acid would literally eat this stuff away. After the first etch, sometimes I could see some remaining unetched patches, so I'd rinse the first acid off and re-etch, concentrating on the unetched parts. When an area is etched properly, you'll be able to tell - it will be rough and porous looking and uniform in appearance.

I used about 2 gallons of muriatic acid (about 9 gallons total solution) for about 900 sq ft on floor. I used a plastic watering can to distribute the acid solution.

 

[sparkplugmstr]

etching

Thanks guys! Bmwpower a tip of the old hat to you I appreciate all the extra tips thanks a bunch!!!! Will let you know how it turns out... sparkster

 

[bmwpower]

No, problem....Anytime. I'm just passing the info along that I learned with the help of a lot of different people, most of them on this site.

I'm getting ready to epoxy my floor, but I have to wait for the darn floor to dry... and it's now snowing outside...great. This garage project never ends!

Good luck!