So you’re at the point where you’re about to prepare your pond for a coating. What the heck is acid etching?
Acid etching is the process by which your concrete will be cleaned and prepared prior to actually applying a coating. Learning how to acid etch a pond is easy, but I’d like to explain the reason for acid etching a little more in depth before we talk about how to acid etch a pond.
All concrete will go through a hydration process for a period of time. The hydration process is essentially the curing process of the concrete. This period of time is usually about the first twenty eight days for normal concrete and sometimes less for more specialized concretes.
During this time the concrete will effervesce, expelling gasses into the atmosphere. The process can be likened to the carbonation process of a carbonated liquid beverage, but on a slower scale. When this hydration process takes place, powdery deposits are formed on the surface of the concrete sometimes referred to as efflorescence.
This efflorescence comes from the calcium sulfates that were used in the cement that was part of the over-all concrete mix. The one thing all of these deposits have in common is they will all more than likely fall off of the concrete over a period of time. Some of these deposits are not readily visible either. The concrete may look clean, but these deposits still exist.
The problem that arises with this if you apply a coating that bonds to the deposits instead of the concrete, when those deposits fall off, so will your new coating. So it is imperative to remove them by this process of acid etching.
Finally, the process of acid etching will also mar the surface of the concrete to some extent. This marring is actually good because if you had a perfectly smooth concrete surface, the coating may not have much to grab hold of when it is applied. This marring usually makes the surface of the concrete feel about as rough as 60-grit sandpaper. A surface like this will allow a coating like Pond Shield epoxy to grab hold with thousands of tiny little fingers and not let go.
The acid etching process is easy to do.
Muriatic acid can be purchased at almost and pool supply store or hardware store. You should use a mixture of one part muriatic acid to three parts water. Then apply the mixture to the surface of the concrete by either brushing or spraying it on. You should use a brush to work the mixture in a little, but no real elbow grease needs to be applied. The acid will do the work for you.
Additionally, make sure you are wearing proper protective clothing and eyewear and gloves while performing this job. Safety first!
Once you have acid etched the entire surface, you simply rinse the pond off with fresh water. You can use baking soda to finish neutralizing the acid/water mixture that ends up in the bottom of the pond and then dispose of properly. If you’re not sure how to dispose of the mixture, contact your local municipality and they can direct you. That’s all there is to acid etching a pond.