why does a blacklighted guitar glow?

[Joe Desperado]

So I have now used a black light to inspect quite a collection of different guitars from the 50's including some LP's. All the straight ones glowed the normal greenish yellow hue. Ones that were touchup up showed obvious traits of work. Refins barely glowed at all. What I can't figure out is...is it the age of the nitro that makes it glow, or is it the compisition of it from back them that makes it glow. I have not had the pleasure to black light an old refin from the 50s or 60's. I know guitars that were refined in the 70's don't seem to show this same affect. Will the eventually glow too?

What say you? Is it age or compisition?

Thanks!
JD

 

[Zoomer]

So I have now used a black light to inspect quite a collection of different guitars from the 50's including some LP's. All the straight ones glowed the normal greenish yellow hue. Ones that were touchup up showed obvious traits of work. Refins barely glowed at all. What I can't figure out is...is it the age of the nitro that makes it glow, or is it the compisition of it from back them that makes it glow. I have not had the pleasure to black light an old refin from the 50s or 60's. I know guitars that were refined in the 70's don't seem to show this same affect. Will the eventually glow too?

What say you? Is it age or compisition?

Thanks!
JD

Old refins glow as well - I had a 1965 telecaster that was refined in 1984 that I played like hell in many a smoke filled bar - I sold it 2 years ago and it glowed under black light.

:2zone,

Zoom

 

[Rev.WillieVK]

I think the glow is due to oxidation or UV degradation of the chemical components of the nitro.

I've heard of nitro that glowed before it was applied, some that started to glow after only 5-10 years, and some that will not glow at all.

 

[retrobob]

I have heard its how much UV light the paint has absorbed.?

Had a 69 LP Custom that had the neck re-finished. It was done before I owned the guitar. I had it aprox. 9-10 years before I sold it.
The whole body glowed florecent green, but the neck was black as night with no glow whatsoever.

Recently did a touchup on a guitar. Had to patch some paint in and then oversprayed & blended the area with clear nitro. Under blacklight, It still glowed even with fresh paint.?

 

[Joe Desperado]

Ok as a follow-up. I black lit my 59 Gretsch that has spent its entire life in the case. (it was one owner under the bed before I got it.) I have only played it under the sun at one festival. Other than that has only been used on stage at night. It glows the same yellow greenish white color as the old gibsons. So at this time I am not inclined to think its completely a UV thing.

I also black lit several others this morning. My tele that I refined in the 80's glowed bright green and it has not been under the sun, but has been out of the case for most of its life. And the strange one is a MIM Fender bass from 93. It black and I thought poly...but it glowed the brightest of all of them.

Anyway, I was thinking it had to do with the quality of cellulious nitrate that was available in the past compared to today.

I sprayed an archtop last summer. Areas of it are also starting to glow under a black light. Especially the edges of the sunburst...and not as much in the center. It was a cellulious base lacquer too.

I would like to here more opinions if anyone has them on this subject.

J

 

[j45]

I've had many guitars from the 90's that glow much brighter than guitars from the 50's. it's no help in determining age, only helps to see inconsistencies in the finish.

 

[Joe Desperado]

ok, thanks. Here is the next question:

If a guitar from the 50's does not glow...was it refinished? A client of mine was looking at a 50's gretsch. All the ones I have black lit have glowed. This one did not. Was it original or refin? Could an old finish not glow?

THanks,
Joe

 

[modoc_333]

as J45 said, a blacklight won't tell you anything about how old the finish is, or if there was a complete refin. the point of putting it under a blacklight is that it will show repairs, partial refins, etc. what you are looking for is to see if the whole guitar is the same color. black, glowing, whatever. if it has 2 colors under a blacklight, then you can see the touchup, overspray, partial refin, repair, etc. if it's all one color, then you just know it was either original or a total refin.
determining whether or not it's a total refin needs to be done in other ways... no blacklight needed.

 

[JIMI55LP]

But still no idea why some don't glow at all or what makes the glowing one glow?

 

[Joe Desperado]

I would think that all the guitars from the same manufacture would glow the same if they are from the same period.

 

[Tom Wittrock]

But still no idea why some don't glow at all or what makes the glowing one glow?

Perhaps the place to start is to find the reason why anything glows under a blacklight.
Knowing that [and I do not] might help explain this.

 

[Joe Desperado]

Maybe I can ask this. .... If you had a burst that did not glow would you be skeptical of the finish?

 

[Tom Wittrock]

Maybe I can ask this. .... If you had a burst that did not glow would you be skeptical of the finish?

I haven't done this with mine, so I would be starting fresh. Since I would normally decide originality without the blacklight, then if it looked original to me before I blacklighted it, I wouldn't be skeptical. Curious maybe. But I would want more time with blacklights and finishes before I would let that one piece of evidence contradict my years of experience.

 

[sharq attaq]

All I know....my Hendrix posters looked totally cool with a black light.

 

[Joe Desperado]

Thanks Tom. Makes sense.

 

[j45]

ok, thanks. Here is the next question:

If a guitar from the 50's does not glow...was it refinished? A client of mine was looking at a 50's gretsch. All the ones I have black lit have glowed. This one did not. Was it original or refin? Could an old finish not glow?

THanks,
Joe

All old guitars, even the from the 50's don't glow...or at least bright enough to look any different from a 5 year old guitar. This is where a blacklight can lose it's credibilty for determining age. The guitars I've owned that didn't blacklight well did have something in common. They were all exceptionally fine examples that showed little or no wear and probably spent decades at a time in a closed case. I'm no expert on the factors involved but this leads me to believe that it is exposure to UV or lack of that contributes to the amount of glow. Like I said before, I've had guitars that were just 6-7 years lod that glowed brighter than some 50's that I knew were 100% straight. Like Tom said an experienced eye just can't be beat for determining originality.

One last thought....I thought I'd add that I've seen a few original custom color Fenders that did not glow at all. This was way back before good refins were common and "aging" wasn't really heard of. I know these were original finishes. I'm pretty sure I recall that most of these did not have a clear coat. I've never owned a blacklight for this purpose but all of my studio rooms have always had large blacklight fixtures so I'm very used to seeing vintage guitars under a blacklight.

 

[retrobob]

Something J45 said about the lack of a clearcoat triggered a thought.
I recall this as well, no clear coat, no glow. With the clear coat, there always seems to be a glow. Certain pigment in the paint? something about clear nitro
that brings the green glow?

But I will say, a guitar from the 50s should show some signs of an aged finish
(if its original) without black light.

 

[RamiLP]

here is my take(opinion) at the black light trick

i have used black lights in working on cars as a mechanic in fixing oil leaks and a/c system leaks. there is the addition of the color of things that you are looking into and the chemical or material.

most yellow/light green colors will glow very bright with a black light and a way to even help more is to get a set of yellow goggles and those enhance the glowing.

i know nitro turns to yellow/amber over time, and its actually somewhat yellow when its still in the can, so the use of a black light might make the laquer glow.


dont hold me by those words because its just a thought.

 

[Electric Lloyd]

When finishing (or refinishing) I use Behlin nitro lacquer. Not the "stringed instrument" kind, but their "Pale yellow" lacquer. This stuff seems to act like lacquers of the '50s '60s, as it checks quite quickly (within a few years) ambers into a nice patina, & glows snot green, just like an old finish under a black light.
Good stuff.

 

[Joe Desperado]

Thanks for the tip!