Muriatic acid on glass

[wilsonline]

So in another forum, someone asked how to clean stained glass. I said that people use acids, weak ones like vinegar (acetic acid) up to strong ones like muriatic (HCl).
So an argument began. lol
The moderator said it will etch glass. I've never seen that.
All I said is you can soak vinegar bc it's weak and may take some time. And if you use muriatic, you should do it outside with ventilation and take the proper care. There is some danger here.
Yes, I tested here. Just dropped 32% HCl solution on top of a tank and also a live rock to see if whatever it reacts with may stain the glass. 1hour later washed the glass and no stain. But that's not very scientific lol.
So, will it etch glass in normal conditions (NTP)?
*not talking about boiling acid or anything ridiculous like intentionally reacting with other stuff to create hydrofluoric acid. Just in the real world of cleaning a stained glass tank.

 

[wilsonline]

Another question is will coralline algae etch glass? So after someone clean the glass with muriatic acid, it looks like the acid etched the glass???

 

[Randy Holmes-Farley]

The diluted hydrochloric acid that we use to clean equipment (1 part acid added to 10 parts water) will not etch glass at room temperature. Boiling concentrated hydrochloric acid will do some etching, but in general, when folks want to etch glass (like the inside of light bulbs) they use (or at least used to use) hydrofluoric acid (do not use at home, it is much more dangerous than hydrochloric acid, even though it is a weaker acid).

I am not sure what happens to coralline and glass, but they do not etch glass that I am aware of (I cannot see how they could). Part of the coralline may remaining after cleaning, if that is what appears to be etching.

 

[wilsonline]

Thanks, Holmes-Farley

 

[schuby]

Can you get etched glass from coralline and an urchin?

 

[wilsonline]

I did a test here as said. Just dropped muriatic acid, 20 Bauer / 32% concentration pretty strong haha, it was pretty warm here (Florida) and it was under the sun. Didn't notice any etching. Actually, the glass came out pretty clean lol.
But looking all over online and only found few things. One article said something about boiling the acid solution at 36% concentration to get some etching. But it doesn't show any picture. Just mention that reduces metals on the surface of the glass or something like that. So I'm not sure if this would be a visible etching or just something microscopic. IDK
And again, that's totally out of question bc nobody recommended boiling a super strong solution of HCl. lol That's just for science. ok.
I did found one comment of a person saying ultra-clear glass could get etching if left with coralline algae for too long. He mentioned this glass is passive to some kind of electrolysis. But no pic or science support on that, just a comment.

 

[Randy Holmes-Farley]

Can you get etched glass from coralline and an urchin?

I think urchins may be able to etch glass.

 

[Randy Holmes-Farley]

But looking all over online and only found few things. One article said something about boiling the acid solution at 36% concentration to get some etching.

That's what I reported above, but note that 36% is concentrated hydrochloric acid. That 36% is not a dilution factor. It is 36% HCl and the remainder water, which is all the HCl that the water will hold before the HCl comes off as gas.