The Harmful Effects of Acid Etching
Making sure your floor has a good adhesion when applying any topical coat to it all comes down to the way the floor is prepped. The best adhesion will need a clutter-free floor which needs to be free of any contaminants. It’s important to understand what acid etching IS to understand why it is bad for your slab and why it will be even worse for your floor.
What acid etching really IS
Acid etching is taking hydrochloric acid (muriatic acid) or buffered phosphoric acid to a slab and then rinsing it off with water. So – for a long time this was what the standard was and just what everyone seemed to be doing. It was the standard used by most professionals and commercial installers depending on the size of the floor being installed.
What is so bad about it?
First – it’s inconsistent. It will remove the laitance aggregate on the top, but it can’t remove curing compounds or any of the contaminants found in industrial settings (i.e. Oil deposits & water insoluble materials). Not being able to remove this stuff means you can’t get proper adhesion.
In addition to that – results can really vary from slab to slab since everyone’s slab can be a little different from one another. So, even when the process is done by the most professional people in the business the results can come out SUPER varied. The surface of your concrete can come out under-etched and sometimes not etched at all OR completely over etched which will result in weak concrete and the use of way more materials.
Generally speaking – acid etching is the weakest and worst way to prep your floor. It measures in one of the two lowest ‘roughness profiles’ out there. While most of the time you don’t want something that roughs up your floor too much, you also don’t want something that doesn’t rough up your floor enough. A good rule here is: the thicker the product, the rougher the floor needs to be. Typically, polyaspartic or polyurea floors and coatings are middle of the road on thickness all the way up to being pretty thick depending on what compounds you have mixed. So that being said – you generally want something that is middle of the road.
Acid etching is also extremely harmful to your slab in the long run. Long after the job is done it’s likely that the acid poured on the floor can stay in it. Concrete floors are porous – while some are more porous than others they are ALL porous. If acid is still sitting in your concrete it can keep weakening your slab and ultimately create pits, cracks, scars, and holes.
Lastly, the final big reason acid etching is a way of the past is time and cost. We know your time is valuable and cost is precious. Making a job take several days is never going to be ideal. With other prep options out there that don’t require a wait time, you can have your floor done in half the time that acid etching would make your job take.