
05/04/2025
Ever taken the time to look at pool plaster under a microscope? In this example, I took a rather low-resolution view of a plaster sample (Pebble finish) and ran a negative of it too.
The last photo, is a high resolution image of teeth-tubules.
I'll ask you to read with objectivity. In comparing pool plaster to a tooth surface, I want to illustrate why we want to avoid muriatic acid (low pH) contacting the plaster surface. In a high level sense we want to protect the equivalent of the "tubule" being opened up.
Think for a moment about eating something cold, a tooth ache, a commercial for sensitive teeth paste. - The purpose of that tooth paste is to keep those tubules capped off and plugged so sensation cannot traverse through them.
Now, over to pool plaster - We don't want muriatic acid on the surface of the plaster, because we don't want to open up the pathways through the plaster that would allow it to be sensitive) often called the capillaries of the plaster.
Muriatic acid takes the top layers and burns them off - and this is why it's so darn tempting (Florida folks listen up) for your pool guys to say "acid wash special, clean pool, pretty pool." Acid is too strong, and absolutely 100% will burn through it. Over and over and cumulatively the plaster will be totally destroyed.
Since I am one to talk about too many topics at a time, let's throw in a fluoride reference and compare this to products such as MicroGlass (and feel free to jump in if you like.) I'm going to say it because that's a cool thing to talk about today. Plaster Logic see if you like this analogy.
The idea behind dental fluoride is to "provide resistance to acid at a lower pH than the natural structure would breakdown at." Normal teeth have a pH of 7.0 and they start to demineralize at about a pH of 5.5 when you have fluorapatite crystals that don't begin to dissolve until a much lower pH of 4.5.
Products that are awesome like MicroGlass which will convert weak calcium hydroxide into Calcium Silicate Hydrate and fill crazing cracks. The point about fluoride vs. MicroGlassglass -- we are taking a compound to convert a calcium based solid into a stronger version of itself (this isn't a debate about fluoride being healthy.) simply to juxtapose (compare the two concepts side by side) and I think this way helps to get people to think. Let me know below if you "get it."
So if you use muriatic acid, you are opening up the channels in the plaster #1 and then, if you don't protect the surface, (proper water balance OR use a sealant) you create an environment that allows breakdown. It also increases the chances of staining. Once the surface is "opened up" you can count on metal stains to sit in that opened up space. As there will be high and low spots.
Eventually, do this enough times - you destroy the surface. End of the story.
Now you are "in the know" - How did we do at telling the tale? Watershape University