Vintage Guitars and Blacklights

This much help I can give you:

Polyurethanes can be made to glow under a black light by the addition of pigments.

That's how we used to inspect clear PCB coatings for coverage.

That's about all I know.

Good luck!

Thanks, that helps me actually. After reading this thread

http://www.lespaulforum.com/forum/showthread.php?t=154986

(the latest debate on the Les Paul Forum on this topic) and hearing your response,

my thought now is that there is a yellow pigment in the nitrocellulose lacquer which has phosphors in it. Guitars without the lacqer normally don't glow under a black light. It is known that many nitrocellulose lacquers are yellow-ish straight out of the can, and also it is known that nitro lacquers yellow over time (which creates an old look or also in the extreme case alters the color of the guitar, eg old blue Fender guitars form the 50's have mostly turned green).

What kind of phosphor could be expected in nitro lacquer?

And could one explain non-glowing 50 year old guitars by showing that the lacquer is still totally clear, without any yellow in it to cause a glow?

Or am I basically off track?

I don't have an exact answer but this true story may help direct you along a positive path. Many years ago, the company I worked for, purchased drawn wire from a well known manufacturer. Some folks were suspicious that traces of drawing lubricant might be left on the wire surface and that it could impact the reliability if the product. The problem was how to detect the presence of lubricating residue. Your's truly, being a young and amitious engineer, obtained a small amount of fluorecent chemical that was soluble in the lubricant. The plan was for us to inspect the finished wire under a black light to detect traces of the drawing lubricant. I mailed the dye sample to the president of the wire company with instructions of how much to add to the lubricant. The president passed the sample along to a forman who passed it along to a female operator. With each passing, some information was lost. The operator dumped the entire contents of this concentrated fluorescent dye into the lubricating solution. She wasn't terribly careful and spilled some of the dye on her hands. During the rest of the day, she touched herself, and soothed various itches all over her body. After work, she headed directly to her favorite disco with lots of flashing black lights. She noticed people staring at her, and when she realized that every part of her body she had touched all day was flashing brightly to the lights, she fainted. There is more to the story, but this is enough.

oH MY GOD this is off topic but aftert reading the last thread i had to tell you . iwas working for a security company we do this bit at the start of a seminar where we plant a flouressed dollar bill on the ground and ask who found it , then use the black light to fine the person if they dont speak up . knowing its a seminar most people say they fopund it then they come tothe stage and show their glowing hands, one time this guy comes up to the stage and we light him up and hes glowwing all over his crotch and butt crack, he must of had crabbs or something.

OMG!

Sorry Guest.

Another perfectly innocent question gets dragged into the depths of depravity by these overactive minds.

Apparently, none of us know anything about old coatings.

Good luck!

LL

Well, these were both very entertaining stories, and at the end of the day that's all I ever really want, a good chuckle!

Re the black light. I've come a long way in understanding what's going on. I still need to research what material in nitrocellulose lacquer is flourescent and how the material reacts with sunlight, oxygen etc.