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Posted by on June 18, 2008, 10:08 pm
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> >I would be worried about the resin leaking through the cracks and making a
> >big mess out of the whole thing. Plus I've seen some clear resin turn
> >yellow. Do you have enough room to just put another piece of glass on top
> >and seal the edges with some clear silicone?
>
> Everything that has been suggested so far will either solarize (turn yellow)
> or quickly decompose under sunlight.
>
> Here's what I'd do. I'd carefully cut away the broken glazing, leaving an
> inch or so around the edges. If it is glass, cut it with a glass cutter. If
> plastic, a scoring tool made to cut acrylic is available at Home Depot.
I would love to see that.
>
> The remaining inch is used to cement a replacement glazing to. I'd go to a
> sign shop and buy a piece of clear >>UV stabilized<<< polycarbonate sign
> plastic. This is a laminate, the outer layer of which is a UV absorber.
> Regular polycarb also quickly solarizes. GE guarantees their stabilized
> polycarb for 10 years of direct sun exposure. Let the sign shop cut it to
> shape to save some work.
>
> Bond that sheet to the perimeter using RTV*. Why RTV? So that when the
> polycarb finally does solarize, you can un-glue it easily.
That would also be quite a good show.
>
> A custom cut piece of tempered glass would be a good alternative but it likely
> will cost more than the panel. I would not use regular glass unless there is
> absolutely zero chance of hail where you live.
>
> The reason that I suggest bonding to a perimeter of old material instead of
> just covering the whole case is that undoubtedly the original glazing mount
> was designed to accommodate thermal expansion. Bonding to the case may result
> in a mis-match of expansion enough to make the seal fail.
>
> * The hazard to copper of moisture-cured RTV, the kind that gives off acetic
> acid fumes, is grossly exaggerated or perhaps just a fiction that's become a
> truism. I couldn't count the number of PCBs that I've potted in moisture-cure
> self-leveling RTV, including some that are undoubtedly still in service at a
> nuclear plant. Like most urban legends, there is probably a kernel of truth
> there somewhere - undoubtedly someone somewhere had problems under
> pathological conditions or perhaps some other contamination caused the problem
> - but it is certainly not as serious as commonly believed.
In fact it can be quite serious. Potting is another matter. Have used
it myself with good results.
>
> I do NOT like the "Silicone II" stuff. It's picky about curing (look up the
> data sheet and see how many things inhibit cure" and it's not nearly as tough
> as the old stuff.
> --
> John De Armond
> See my website for my current email
addresshttp://www.neon-john.comhttp://www.johndearmond.com<-- best little blog
on the net!
> Tellico Plains, Occupied TN
> No one can be right all of the time, but it helps to be right most of the
time. -Robert Half
Given that the panel in question is an amorphous panel it is, in
reality, hardly worth worrying about repairing.
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