Severe hard water on plexiglass glass?

Hi guys, I had posted an earlier thread about hardwater deposits on some bus shelters. Thanks to some tips I got here and a Mr. Hardwater polishing kit, they are cleaning up quite well, but now I’ve discovered that one of them is actually plexiglass.

Is there anyway at all to deal with severe hazing from mineral deposits on plexiglass or is it pretty much a loss?


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Hi Mahlon,

Acids tend to react with glass surfaces. Organic solvents will do damage to acrylic and polycarbonate surfaces. Acids tend not to react with acrylic. And solvents will not damage glass. So there might be acids out there that will eat up the mineral deposits without doing any harm to the plexi. I would not rub hard. Rather I would use a light soft brush. Once the deposits have been removed you could polish to clarity with a special superpolish for plastic.


Thanks Henry! Any particular acids you would recommend? Something on this site?

Btw, your wobble wheel is awesome! Only thing is you need to make it with a grinder attachment. There is nobody making a commercial adapter that I can find. I used my electric drill for awhile, but I’m having a local shop make an adapter so I can use it with the angle grinder/polisher. I think that then it will be truly awesome.

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i would bet a considerable amount of rubles that the plexi is wrecked so bad no cleaning process will make it look good. plexiglass simply cannot stand up to any kind of wear and tear. the fact that it was used in a bus shelter application indicates pretty clearly that this was a “cheap fix” situation, probably a replacement for badly vandalized glass.

i would clean it with traditional methods and recommend replacement with real glass.

TRUE. I would use traditional. After, using Pledge furniture polish will improve the look.

These guys are very likely right on target. I am always the theorist. The actual practical truth many times is very different.

I dare not suggest any acids since they can do harm to your own body and the environment.


Thanks guys. I’ll let the client know not to expect much.

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You might want to check some automobile detailing forums. They deal with damaged plastic quite often. My favorites are and

I accidentally put swirl marks on a plexiglass skylight. I did some research and I found out how to fix it like new.
Google acrylic scratch removal / restoration / polishing
Or you can also look it up on YouTube

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