Anyone know anything about Glass Polishing/Scratch removal?

[Saladsamurai]

In my lab we have these glass viewing windows that are affixed to a combustion chamber. We've recently been experimenting with some new fuels that have some pretty nasty products of combustion. As a result, the windows have become "cloudy."

At first, I thought it was just a nasty film that had developed on the glass, but it is actually some very mild erosion that is occurring (likely due to the acidic nature of the HF in the products).

These windows are quite expensive as they are 1.5 inches thick and are made of fused silica. Though we have ordered new glass, cleaning these up seems like a great idea.

Anyone have any experience with glass polishing that could make a suggestion as to where to start on this one?

What kind of products should I be looking into?

[turbo]

Have you thought about using tin oxide powder? To preserve the flatness of the windows, you night have to apply the tin oxide using a piece of plate glass as a tool. You might haunt the amateur telescope making sites for sources of polishing compounds.

If you want quick-and-dirty, you could try something like this:
http://www.properautocare.com/polishglass.html

[lisab]

No idea how to fix up the old ones. But when the new ones are installed, I'd try to find a way to protect them from a similar fate. Maybe put in a cheap sacrificial liner (acrylic or ???) that could easily be replaced once it gets ruined.

[Saladsamurai]

Have you thought about using tin oxide powder? To preserve the flatness of the windows, you night have to apply the tin oxide using a piece of plate glass as a tool. You might haunt the amateur telescope making sites for sources of polishing compounds.

If you want quick-and-dirty, you could try something like this:
http://www.properautocare.com/polishglass.html

No idea how to fix up the old ones. But when the new ones are installed, I'd try to find a way to protect them from a similar fate. Maybe put in a cheap sacrificial liner (acrylic or ???) that could easily be replaced once it gets ruined.

Thanks for the replies folks :smile: I am not too concerned with the new ones as they will not be used with these fuels. I think we may have to use windows of a different material altogether for these other fuels (perhaps some kind of plastic as I hear hydrofluoric acid does not react with plastic like it does with glass).

I figure if I can get these windows polished up a little, I could dedicate them specifically to the newer damaging fuels until a more permanent solution comes about.

[turbo]

Be aware that if you use Lexan windows, that material is quite soft. It is highly shatter-resistant, but that toughness does not equate to resistance to mechanical abrasion. When I was a dispensing optician, I always suggested Lexan lenses for kids because of the shatter-resistance, though I'd have to educate them and their parents in the proper cleaning/maintenance of that eyewear.

[MATLABdude]

HF is used as an etchant for glass / silica / quartz. Even in the gas phase, it can do some damage. Etching also tends to result in etch products that partially mask sites on your glass so that it 'frosts' (like in decorative windows) and otherwise renders originally-transparent pieces of these materials partially or fully translucent.

You'll have to find a protective coating for your glass to keep this from happening (if that's a concern), and still survive the high temperatures the system is working at (I assume, since you mention this is a combustion chamber). Teflon or kapton coating? Diamond CVD (if the glass piece is small enough, and there's CVD system that can do it)?

Unfortunately, hydrofluoric acid will also etch polycarbonate (lexan) and isn't so great for PVC either (just select hydrofluoric acid, 20% to get an idea of what it is and is not compatible with):
http://www.coleparmer.com/techinfo/chemcomp.asp

As for polishing up your existing pieces, I'd suggest looking for glass shops in your area--particularly, scientific or artistic would probably be better than the ones that install windows and the like.

[narrator]

My wife and I used to sell Murano (Venetian) Glass sculptures and had to repair some damaged items. We found a glass repairer in the phone book. I watched him work, he used 2 long flat belts on pulleys, with running water. One had a very fine abrasive, the other was for polishing after the first. Did a great job and was very cheap. I took 4 sculptures for repair, the largest being almost a metre long, the smallest about 15cm (6") in dia. an hour and a half later, all 4 items were repaired for a cost of AU$90.

[Proton Soup]

you can get aquarium scratch removal kits for either glass or acrylic.