How to Clean and Seal a Slate Shower
LESLIE: Now we’re going to take a call from Scott in Texas who has a slate shower issue?
What kind of issue is that, Scott? What’s going on?
SCOTT: Well, what I have is a natural slate shower set in a thinset bed. And what’s happening is I’m having efflorescence problems which is bringing the white, mineral deposits to the front of the stone. I have tried cleaning it with everything under the sun from muriatic acid to specialty products and I just can’t seem to get it to clean that film off. And I was wondering what can I do to clean the film and then reseal it so this won’t happen again?
LESLIE: Well, generally, I find slate is never sealed; or almost never. It changes the look completely if it is sealed.
TOM: Yeah, the mineral salt deposits might be because you have hard water. Are you on well water, Scott?
SCOTT: No, it’s city water and it’s pretty soft.
TOM: Hmm. It is? OK, well to clean the salts, use vinegar. Vinegar will melt the salts away. So a vinegar-and-water solution is typically what you’d use to clean the salts.
If you want to reseal the slate, you could use a masonry sealer for that. That’s going to probably stop some of the absorbing qualities. But keep in mind, Scott, it’s also going to change the color of that slate. It’s going to get darker. So it’s a tradeoff between the maintenance issue and the color issue.
SCOTT: OK. And so the vinegar would cut through what muriatic acid wouldn’t?
TOM: Well, if it’s a salt deposit, it’s a mineral salt deposit, it’s what left over when the water evaporates and leaves its salt behind. And vinegar, if you remember science class, melts away salt.
SCOTT: Right, right.
TOM: So, that’s the first step.
SCOTT: And then once that’s done, if that works satisfactory, just go back and clean it with a sealer that can withstand, I guess, constant water.
TOM: Well, a masonry sealer. Typically, they’re all exterior-grade, so they are going to withstand the water.
SCOTT: OK. Well, I’ll give that a try.
TOM: Alright, Scott. Thanks so much for calling us at 888-MONEY-PIT.