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View Full Version : OT: Am I likely to damage this lens if I heat it??



RPease
01-24-2009, 11:23 PM
I realise this isn't machine related, but the part is sitting on my lathe table, so maybe that's close enough to "almost qualify"..........

My scuba mask has prescription lenses. I was having trouble seeing my air guage and compass (underwater) with them because I'm so nearsighted. I let a dive shop put a small magnifying lens on the inside of one lens. They used a clear silicon glue, but the glue layer developed some small air voids that make the magnifier useless.

Now I'd like to take the small magnifier out (it kind of blocks my vision) but I can't get the silicon glue to release. I've soaked the whole lens in acetone, coleman fuel and gasoline, but nothing seems to dissolve the glue. The glue layer is very thin, so I guess the solvents can't get between the 2 glass layers to attack the glue. Since the lenses are glass, I figured there shouldn't be any danger of hurting them with the solvents, but it didn't seem to work anyway.

I was thinking about using a propane torch to heat the lens to get the glue to release, but before I did, I wanted to get a few opinions from you guys. Since the glass is tempered, would that present any problems. I don't plan on heating it too much. Just enough to soften the glue, but I don't want to damage the temper.......if that's possible??

Any problems that you think I might encounter??

Thanks in advance..............Rodger

spope14
01-24-2009, 11:37 PM
Go with a hair dryer on low or medium first. I think that with a propane torch, you may actually thermal shock the thin layer of glass underneath the lens and crack it.

RPease
01-24-2009, 11:51 PM
Thanks.........I wasn't sure a hair dryer would get hot enough, but it's certainly worth trying. Guess I can always move "up" in heat. Maybe I can try a soldering gun too.....If the hair dryer doesn't work. I don't have a "heat gun", so that's out.

I also don't mind hurting the little magnifier, although I'd rather not take a chance on damaging anything (except the silicon :D ............if I can keep from it.

Thanks again..........

dbc58
01-25-2009, 01:26 AM
There is nothing that will dissolve silicone. It is going to be hard because you can't grip the lens. I don't think heat is going to do you much good here. RTV does not really soften with heat. I would first try to slice/lift it off with a razor blade. Once the lense is off it will be easy to remove the glue from the glass. More risky behavior would be to break the small lens and remove it piece by piece.

From GE's website:

"How do I remove silicone products?
It is VERY difficult to remove silicone from a surface. However, if you must remove it, follow the suggestions below.
To remove silicone sealant from surfaces, first remove as much as possible by cutting/peeling/scraping excess sealant from surface.

For ceramic tile, marble, Formica>>, fiberglass, etc., use 100% mineral spirits (turpentine) and a non-abrasive scouring pad. Test solvent on a hidden area of the surface to ensure that discoloration will not occur. If discoloration does occur, contact the manufacturer of the surface for further assistance.
For glass surfaces, use a razor blade to remove as much as possible, then apply mineral spirits. Remove excess as much as possible, then apply mineral spirits. Remove excess with a towel or other suitable cleaning utensil that will not mar the surface (such as a non-abrasive pad).
NOTE: For surfaces such as hard plastics or painted surfaces, including cars, use rubbing alcohol and a soft cloth. Do not use mineral spirits. Only use these solvents in a well-ventilated area and follow all safety precautions and instructions listed on the product label. Material Safety Data Sheets for GE Sealants & Adhesives products are available upon request. Similar information for solvents and other chemicals you choose to use with GE products should be obtained from your suppliers. When solvents are used, proper safety precautions must be observed. On Rough, Porous Surfaces>
To remove sealant from a porous/rough surface, (concrete, brick, wallpaper) remove as much of the sealant as possible (same as smooth surface). If necessary, use a wire brush in conjunction with mineral spirits. NOTE: We do not recommend use of a wire brush to remove sealant from wood surfaces, as doing so could damage the wood. Also, mineral spirits should not be used if the wood has any type of finish on it. Test solvent on a hidden area before applying. Mineral spirits are flammable and should be used away from sparks, flames and other sources of ignition. Only use these solvents in a well-ventilated area and follow all safety precautions and instructions listed on the product label. Material Safety Data Sheets for GE Sealants & Adhesives products are available upon request. Similar information for solvents and other chemicals you choose to use with GE products should be obtained from your suppliers. When solvents are used, proper safety precautions must be observed. NOTE: There is nothing that will dissolve silicone. NOTE: If reapplying silicone to the area, remove the old sealant. Then clean the area with a disinfectant if mold or mildew is present, apply rubbing alcohol. Let the area dry before re-applying silicone.<> Do not use soap to clean surfaces to be sealed because silicone will not adhere to surfaces covered with any soap scum."

boslab
01-25-2009, 01:58 AM
try
http://www.cglass.co.uk/everbuild-everflex-silicone-eater-pr-17657.html
silicone eater
mark

winchman
01-25-2009, 04:35 AM
Last resort:
Use a Dremel tool to grind the lens until it's very thin, then peel it off with a razor blade.

Roger

Evan
01-25-2009, 05:29 AM
Don't use heat. There is a good chance of cracking the glass. I would try a new double edge flexible carbon steel razor blade and try to slice it off.

RPease
01-25-2009, 05:13 PM
Thanks all........If worse comes to worse.........I'll just buy a new prescription lens. The way my eyesight changes, I'll need it anyway.......:D

Best regards............Rodg