Re: Glass Chip: Do we have an authority on glass?
- From: Neon John <no@xxxxxxxxx>
- Date: Tue, 29 May 2007 23:26:58 -0400
I'm not a car windshield specialist but I DO have a lot of experience with glass.
The concern is whether there are micro-fissures and/or stress risers in the glass
wound that will allow cracks to form when the weather changes. It is very hard to
tell by looking, even with a microscope.
The procedure I use is fairly standard for all sorts of glass wounds. Basically,
grind out the damaged part, polish the work area and optionally, fill the wound with
optical cement of the same refractive index. That's what the Permatex kit is that
Sandy mentioned, though there are much stronger adhesives available if one has a UV
lamp to cure it with.
The basic drill (heh!) is to grind out the damage with a tiny diamond burr mounted in
an industrial version of a dental drill. A dremel tool will work but much slower. I
grind the damage into a smooth hemisphere. Then starting with carborundum or diamond
dust and working up to cerium oxide on hard felt tips, polish the work area back to
the original finish. What results is a tiny concave lens. If that's in your line of
vision then fill it with optical cement. Otherwise leave it be.
Diamond burrs last almost forever if used wet and mere milliseconds dry. My drill
sprays a jet of mist but I try to arrange a garden hose to trickle water down across
the work area. You can do the same with a dremel tool.
If there are cracks developing then the procedure to relieve the stress is to drill
into the end of the crack with a tiny diamond bit, then fill the hole with optical
cement. The much larger radius of a hole of even a few thousands diameter spreads
out the stress that remains. I get my 1/8" shank (standard Dremel) micro diamond
glass drills from a jewler's supply. The smallest I have is 0.015" and I think they
have smaller.
The kit that Sandy mentioned works well IFF there is little residual stress and no
stress risers. If micro-cracks are present then they'll probably run despite the
adhesive. The adhesive is actually more effective once cracks have formed because it
can wick into the crack and bond the sides together.
If it's a very minor wound with little penetration then I'd leave it alone. If not
then I'd grind it out (or have it done) to be sure.
John
On Tue, 29 May 2007 10:08:09 -0400, "Steve Wolf" <news@xxxxxxxx> wrote:
I have the tiniest of chips in my motorhome windshield. There are no---
cracks. It is simply a tiny chip. I called around and the local companies
don't do anything until there is a crack radiating out from the chip. My
last motorhome had a chip that eventually resulted in a crack. It did that
when it was 70 inside and minus 5 outside.
I am looking for information from someone who actually took action on a tiny
chip. What did you do? Alternatively, I am looking for someone who is
fluent is the technicalities of automobile glass who can confirm that a tiny
chip isn't something that calls for action.
I know about kits that are available and am not seeking that type of
information. I'm more interested in if we have a good glass guy or girl
here who has enough hands-on experience to speak authoritatively on the
subject of large motorhome windows subject to significant temperature
differentials.
Thanks,
Steve
www.wolfswords.com under the motorhome link
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
Save a tree, kill a beaver
.
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