Teonex Film

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Very interesting. I do worry that the "high rigidity" they tout sounds like high stiffness which, in turn, makes it seem like it could be "crinkly." That's complete conjecture, though. I have zero experience with the material. It would be great if it proved to have advantages over mylar.

When you shrink a film like Mylar or Teonex with a hair dryer on your ESL panels and then it relaxes, can you heat shrink it again or have you used up all the shrinkage potential?

Hello Bentoronto,

Most of the high-grade Mylar used in ESLs will shrink about 1.5% - 2.0% when heated to 150 -160 degC. Temperatures less than this do not permanently shrink the film.
In general, hair dryers are not able to achieve this temperature. A heat gun is usually needed.
Of course you also need to be careful with heat guns as it is frustratingly easy to melt holes in the Mylar with them if you aren't careful.
I use a temperature controlled hobby iron to heat shrink the Mylar during construction.
Capaciti gives some details on the technique he uses to get the right temperature with a heat gun. This same technique could be used to re-shrink Mylar in ESLs after assembly.

Concerning re-shrinking Mylar, I have found that once properly heat shrunk Mylar seems to be pretty stable.
Even 4 years of constant playing and there is very little if any drift in the resonant frequency of the panels I have built.
Out of curiosity, I did try to intentionally stretch the diaphragm with a pencil eraser on a test panel to see what would happen.
It left permanent deformation marks in the mylar and reduced the tension. Re-heating the Mylar worked well. Tension returned to its original value and no visible signs of the deformation remained.

Heat shrinking does not work well for re-tensioning IF:
1) diaphragms were originally stretched during assembly to achieve higher tension than possible with heat shrinking
2) diaphragms were assembled with different vertical and lateral tensions, like curved ESLs.
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