Thursday, August 10, 2017

How do I prep new and smooth concrete for sealing?

Q. -  I have a new (3 month old) concrete basement floor that I would like to seal.  I do not want to stain the floor, just seal it.  What prep work is required other than cleaning the floor to use Clear Shield concrete sealer?  Does the floor need to be etched? It has a relatively smooth trowel finish.
Thanks, Matt



A. -  Essentially it just needs to be clean and dry. However, how smooth or how porous the concrete is directly effects how well the sealer can bond and hold that bond. That's why many sealers and also acrylic stains etc., tell you to etch the concrete first. They're trying to get the concrete as open and porous as possible so their product will have a better chance at not peeling up. Clear Shield Premium was designed to bite into the concrete, which is one reason it outperforms most others. Though Clear Shield sealers are usually put on concrete that has been acid stained (or a broom finish etc.), which means the concrete was lightly etched. So while I don't want to steer you away from acid washing, you may be able to just go over it with a rented floor buffing machine using the aggressive stripping pads and open the pores up enough to be sufficient. If you do decide to acid wash it, then use 1 part muriatic acid to 5 parts water and spray that on and allow to dry. Even though you're not staining the concrete, if you use any kind of acid washing or etching product, you will still have to neutralize it after it has dried (with 4 to 6 ounces of ammonia to 1 gallon of water sprayed on) and rinse it really well a couple of times, just as you would if staining it. If you don't neutralize the acid then the sealer won't be able to hold its bond no matter how rough you got the concrete.

So, it's up to you. The buffer with the black stripping pads will work well so long as you go over it well a few times. You could use T.S.P. (tri-sodium-phosphate (phosphate free of course)) and water with the scrubber and the rinse really well a couple of times and that should do it. Though acid etching is also a fine option and may be a bit less work while opening the pores up a bit better.