AD clock image preservation

[gigantea]

I've had this advertising clock for years now. I went through it a long time ago and saw that the image stuck to what seems like clear plastic is still perfect. I would like to keep it that way as long as possible. One way of course is to use LED bulbs to keep it cooler in there rather than use filament bulbs, or not use bulbs most of the time. I was wondering if anybody has come up with another technique to preserve the image, keep it from peeling off like I see pictures of that happening so often.

 

[shutterbug]

LED is a good idea. Maybe the smaller low voltage types would be better?

 

[gigantea]

I put the smaller LEDs in there, something like 1" diameter, practically no heat that would do damage over time. Been fantasizing over something like a thin epoxy sandwiched under another round cut thin piece of Plexiglas. But, if it's not broken, don't fix it works too.