Can I acid etch concrete for epoxy installation? We all make mistakes… And we can learn from them.
I remember doing my first epoxy garage floor and following the paint stores instructions on acid etching the concrete. Being a painter, how hard can it be to roll on sticky garage floor paint… ¯\_(ツ)_/¯
So, I went to the local hardware store and bought a garden pump sprayer, that did not last long… with a gallon of muriatic acid. I was very determined to do a good job, and I understood the concept, that the acid would burn tiny little holes in the concrete as so the epoxy had a proper surface to bond. Easy enough… So, I started spraying in circles, the muriatic acid, on the new garage floor and I could hear and see it was doing its job, by fizzing and turning yellow. After the gallon of acid was done fizzing, I proceeded to rinse the concrete floor.
A few hours later it dried and I was ready to put my Safety Red epoxy down on the floor. Again following the paint store’s instructions. Then I mix the batch, squeegeed it out on to the floor and back rolled the epoxy. It was beautiful! The homeowner just pulled into the driveway and was very happy, for a short while anyway…
Learning from our mistakes
Three days later, I received a call from my client, saying that the epoxy was peeling! Peeling? But I followed all the instructions, I acid etch the floor, let it dry, and mixed the epoxy correctly. Hmm… so, I went back to take a look. Sure enough, it was peeling, flaking off with my thumbnail. So, I power washed and scraped the epoxy floor off. I called the rep out to look at the floor and went over the details of the installation. He noticed the concrete had a yellow haze to it still. He asked if I neutralized the acid PH of the floor. PH? See when a floor is too acidic, the epoxy will not adhere to the floor. So, I power washed the floor again and scrubbed the floor with baking soda and really cleaned it well, while neutralizing the PH. I then purchased more epoxy and redid the floor. This time the floor was done correctly.
27 years later, I recently came upon a floor that was peeling everywhere and severely pitting the concrete. It looked 50 years old. This was a very nice house and relatively new. I asked the homeowner when was the floor epoxied, she exclaimed 2 years ago! but pointed out that it was peeling almost immediately after the initial installation. The floor was slightly reminiscent of what I had seen and done 27 years earlier, without the pitting.
Experience pays off
I asked if the contractor had diamond ground the floor, like what we were about to do, on this floor. No, she said. Then it dawned on me, he was a painter! So, in my opinion… I believe the contractor did what I initially did all those years before… He possibly acid etched the concrete slab without neutralizing the acidity, prior to installation and with the concrete being acidic; I believe this accelerated the pitting.
My point is… every failure is an opportunity to learn something. You may acid etch a concrete floor for epoxy… just neutralized it!
We mechanically diamond ground the floor below.