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Old 10-26-2012, 04:57 PM   #15
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OK, I have attached two nice closeups below. I'm sticking to my earlier assertion that the amber crystals are some chemical that is precipitating/outgasing/growing out of the aging rubber, for the following reasons:

1) They are found all along the rubber seal material, even on the upside down and vertical parts. I have a hard time believing that dessicant sprinkeled into the airgap between the windows 40 years ago would not have shaken down to the bottom.

2) One of my wing windows is original and is sealed with the black stuff (that has crystals growing out of it). The other has been repaired at some point and was done with some kind of grey glazing putty. They both have some moisture (fog) between the panes, but no crystals in the grey glazing putty.

3) If I look really closely, I can see tiny crystals that are just emerging from the rubber.

Some time in the near future, I will pull the window frames apart and rebuild/reseal the windows. I'd be glad to save a sample of the crystals if someone has access to a mass spectrometer and would like to do a detailed analysis. Any grad students out there looking for a thesis?

Since there seems to be some fans of Wikipedia on this thread, I went ahead and did a little search for "crystalized rubber," and low and behold, got a wiki hit:

Strain crystallization - Wikipedia, the free encyclopedia

Not a very enlightening article, but the gyst is right here:

Strain crystallization is a phenomenon in which an initially amorphous solid material undergoes a phase transformation due to the application of strain. Strain crystallization occurs in natural rubber, and some other elastomers. The phenomenon has important effects on strength and fatigue properties. There are various techniques for measuring crystallization in rubber, including: x-ray diffraction, specific heat changes, and density changes.

Because I tend to over-think these things, I did some more looking, and I have bad news for my budding grad student that might have gotten excited at the above. The study has already been done, you can find the dissertation (bed-time reading) at the link below (there are some sections in German, but don't them them slow you down). It gets really interesting around page 92 "Deformation-induced crystallization in polyethylene-polybutene copolymers depends on temperature and strain rate in a similar way as does polyisoprene rubber, although the molecular rearrangements taking place are dfferent. In the early stages of drawing an unoriented crystalline polymer, spherulites become..."

http://tuprints.ulb.tu-darmstadt.de/...ssertation.pdf

Ah...so if I take rubber and squeeze it between two sheets of glass for 40 years, it might undergo a phase transformation, producing crystals. QED. Guess I still have to take the window apart or live with them.
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Old 10-27-2012, 07:55 AM   #16
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1976 31' Sovereign
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Belegedhel: That's pretty much the conclusion we were drawing and makes the most sense. "Dan" had been parked in the shade for the last several years and since the end of June, has been parked directly in the sun, although the roadside has not been directly in the sun (the crystals are predominently on the curbside with only a few on the roadside). So there has been a change in the way the airstream has been exposed to sun and heat....Wow you have a lot more crystals than we do and I can see that if not taken care of, it can get a lot worse. Looks like we know what you and we will be doing in the not so distant future....Thanks for the research...........Janet
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Old 10-27-2012, 05:05 PM   #17
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Make some Airstream jewelry out of them.
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Old 10-27-2012, 06:04 PM   #18
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Whether it is rubber or diamonds, it's just a bunch of carbon, hydrogen, and oxygen, right?
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Old 10-27-2012, 06:27 PM   #19
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Indeed.. Vintage carbon, hydrogen, and oxygen :-)
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Old 02-02-2016, 03:26 PM   #20
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It's been a while since the posting about the strange Crystals growing between the windows in our 40+ year old Airstreams. I too have this amazing growth of not only golden, but also purple crystal growing in my windows of our 1976 Overlander. I call it my
Amber and Amethyst collection and I show it to everyone. Should I ever replace my windows, I promise to post picture of the jewelry that comes from these lovely stones.
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