Which Acid Works best on what?

I’ve heard of a few different acids not sure what works best on what.

Hydrochloric acid: I’ve heard this is what’s in Crystal Clear 550?

muriatic acid: I heard this is used on brick… Is that right?

Phosphoric acid, I’m not sure what this is used for.

What’s the differences between the acids?


That’s hydrofluoricacid in CC550

Yes. Muriatic is hydrochloric at 20%. CC550 uses hydrofluoric (with an F) at about 1 percent. Phosphoric is another mineral acid. So is sulfuric. Certain mineral acids like hydrofluoric will etch glass surfaces. There are also organic acids. Some of these organics are rather powerful and can help in removing hard water spots. Typically the only acids that will chemically attack water spots based on silicates are those that will also etch glass because glass is made from a silica/silicate matrix. The different etchants (mineral acids) will attack glass in different ways (different chemical reactions) because the chemistry is different.

I had lots of fun with acids when I had my kitchen/lab set up 22 years ago. Had about four large jugs of hydrofluoric acid under my bench. A 50% concentration of sulfuric acid. Pure sparkling white crystals of ammonium bifluoride. An 80% concentration of thick syrupy phosphoric acid. A 20% tall bottle of nitric acid. And much more. All the organic acids like sulfamic, oxalic, gluconic, glycolic, acetic, etc. Not to mention one badly stained stainless steel sink, and many pounds of destroyed glass I bought new from the local glass shop.

But to answer your question. Mineral acids like hydrofluoric, sulfuric, and ammonium bifluoride will remove hard water spots that are based on silicates. These usually come from bricks and concrete. Problem is they will also eat up glass which has a very similar chemistry. The organics and non etching mineral acids are good at dissolving water spots that are not based on a silicon chemistry (no silicates). So mostly calcium based spots. These spots can come from ground water in sprinklers. Or not. It depends on the chemistry of the ground water. Where as bricks and concrete have essentially the same silicate based chemistry. Every time.

Hope this helps.



I know this wasn’t your question but ever use Safe Restore?

I found this to remove deep hard water stains along with aluminum frames.

Chloric acid is best used in a plastic drum to dissolve a corpse. Preferably a competitor’s. Just saying, I saw it on Dexter.

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Yeah. They also use sodium hydroxide to liquify dead horses. I guess that is why P & G used it at 1% to Dawn. Good for dead horses good for greasy dishes.

Anyhow. Regarding Safe Restore. Otherwise known as One Restore. I really don’t like to knock products. And we do know that Safe Restore does work most of the time. But we have also heard some reports from other guys that you must use caution otherwise bad stuff can happen to your window. A look at the MSDS shows hydrochloric acid at 5 ppm. The other ingredients are a trade secret. So if there are any glass etchants used they are not going to tell us. If you want to test it I have developed a few very simple tests using brand new glass samples. These tests are explained on my Products blog.



Okay, thanks for setting me straight.


WOW! I had no clue there was so much to this!

I’ve talked to someone at Winsol and the lady said that 550 doesn’t chemcally etch glass (I’ve always heard it does.) She said that if it’s left on too long it will “smoke” the glass…

Thank you for sharing!!! I really appreciate your insight and knowledge about this stuff! :slight_smile:

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I haven’t tried it. how does int compare to 550?

Smoking is a casual description of cc550 reacting with tin in some glass.

Etching glass is didferent, etched glass looks white/yellow like frosted or sandblasted glass and is done for privacy or decorative effected.

Smoked just means you f cked it!

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These so little “nasty stuff” in one restore that it doesn’t even shop as hazardous goods!

Okay that makes sense

Is the tin side not on the 3rd or 4th inaccessible surface?

That where is should be. But everyone makes mistakes and sometimes the glassies assembled the window inside out.

Yah that’s horse pucky. It doesn’t “smoke the glass” As window gleam stated it has to do with the tin side reacting to the acid.

It also doesn’t matter how long you leave it on for. It will very slowly eat at the glass but it has the same effect whether it’s on there for 1 minute or 5 minutes or an hr. It will have a worsening effect when left in the tin side. The longer it’s left on the worse the reaction.

Another myth is that you should apply it in the direct sunlight. That’s his wash as well. I did a large glass restoration job once where the guys left it on the glass and we went to lunch. It was in the middle of summer in direct sun light :scream:. Came back and guess what? No smoke! :sunglasses:

One thing you will find is that those who manufacture a lot of the products on the market don’t even know that much about their product so you want to be aware of that when you take advice from the manufacturer. Do your own research or you may end up paying out a settlement worth thousands of dollars of damaged glass.

The best approach is to check for tin side using a black light. Use CC550 on the glass where the tin is not exposed and on the rest you will have to use a polishing compound which is a whole other animal in and of itself.

Your best bet is to use A-1 by hand on small window jobs where you need to do 1 or 2 panes and stay away from large restoration jobs until you understand most of what there is to know about the products your using (including job experience with those products) and you have the process down pat.

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I have done many experiments with CC 550. The advice here about not taking any advice from manufacturers is good advice. Although you might check out Winsols MSDS for their product CC 550. http://www.winsol.com/550MSDS.htm You will find two acids listed. One of which is hydrofluoric acid. I have done many tests with this product. Also pure hydrofluoric acid at different concentrations. It is amazing to me that the window cleaning world is still using HF on glass twenty two years later. I shouldn’t have to say much more. Just jump on the youtube and other sites and read about it. Simply put HF breaks down the silicate/silica matrix of soda lime glass. This happens in as little as thirty seconds. I can show you this. It is hard to get on camera. But I should definitely do this at our meets. I am working on getting down to Fishkill for the first meet. Ricky Cosh has been working with me on getting this together at the famous 84 Diner. We are looking at early Spring.


I really like simple things like ok barkeepers friend foam cream and powder they probably will never hurt glass a lot of it is based on citric acid like orange stuff but I am try some of that

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Simple is good. Citric is an organic acid. Not mineral.


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