Official Luthiers Forum!

Thanks again to all who responded to my earlier thread last fall about this.
To update, I located a UV curing booth at Gerhard Guitarworks aboout an hour
south of me in Windham NY.
Cue Gerhard was very accomodating in this project to darken a completed
French polished guitar.
Here is his booth:
This utilizes specialized tanning lights which have a built in reflector that focuses the UV A and B wavelengths into a narrower directed beam than regular UV bulbs.
We first exposed a test piece that I had prepared by FP'ing a similar top to the subject guitar
which was divided, one half for the test, the other to be maintained as a control.
I also included halves of the soundhole cutout on each piece to get a look at the effect
on the actual piece of spruce to be darkened.
Cue exposed the test pieces to 1/2-1 hour of exposure each day, tracking the temperature and humidy in the chamber with an eye toward avoiding "cooking" the instrument once we progressed to that stage..
After around 35 hours of exposure we could clearly see darkening of the spruce at least 2-3 shades
(on the grey scale).
The guitar was similarly exposed to the same excellent effect.
In between sesions it was kept in a humidified room and I took the further precaution of hanging D'Addario humidity control system packets inside to counteract any dryng effect of the lights while in the booth.
The final result was quite good and inclided a nice darkening of not only the spruce, but the holly bindings and purflings as well as the mahogany of the neck.

Question: Have any of you used UV on a guitar with celluloid bindings/purflings and has it had a noticeble (deleterious) effect on these?

Again, Thanks to all.