LowE
Active member
- Joined
- Nov 16, 2005
- Messages
- 2,454
I know some of the answer, but not all. First you have to know that a blacklight tube is a type of flourescent lamp (FL) as opposed to the regular domestic light bulb which is incandescent light (IL). An old fashioned IL works by basic heating up of a coiled metal filament (usually tungsten) via electricity, and the metal glows hot and gives off visible light which you can see.
With a flourescent tube its not the heat, but a mercury gas inside the tube which when excited by the electricity causes ultraviolet light to be emitted (from the mercury). A FL only sheds visible light if you coat the tube with a material that glows when exposed to ultraviolet light, otherwise, if it were just plain glass you wouldn't see anything at all, there'd be plenty of UV light emitted but it'd be pitch black in your room. The material that you coat a FL with is called a phosphor, and can be any of a range of materials that emit visible light (different colors depending on the material) when you shine UV light on it. Black lights are just like regular flourescent lamps, but instead are made of a glass tube that is black instead of clear (to absorb bad UV I believe), and it is coated with a phosphor that glows faint purple when exposed to the UV light. With a blacklight, there is both visible light being emitted in the purple frequency (the lowest freq), and there is also a lot of UV light emitted you can not see.
When you shine your black light on a guitar, you are seeing two effects. One is the simple reflection of the visible purple light that is coming off the tube and lighting up the room - and the other is the reflection of the UV light off the guitar, which can ONLY be seen by your eyes if there is some phosphor on the guitar. If there's no phophor on the guitar, you'll only see it normally in the room like everything else that is reflecting the visible purple light. But if there is phosphor, which I assume is in the yellow pigment of the nitro, and possibly in some poly too if it's yellow or otherwise tinted, then you will see glowing visible light due to exposre to the UV.
What I still don't understand is what kind of phosphor is in the nitro lacquer, and how does it react to exposure to sunlight?
When you look at a typical old Fender, the decal is over the finish and somehow protects the phoshor below it. It glows bright compared to the headstock. Protects it from what? From oxidation, from sunlight, something else?
With a flourescent tube its not the heat, but a mercury gas inside the tube which when excited by the electricity causes ultraviolet light to be emitted (from the mercury). A FL only sheds visible light if you coat the tube with a material that glows when exposed to ultraviolet light, otherwise, if it were just plain glass you wouldn't see anything at all, there'd be plenty of UV light emitted but it'd be pitch black in your room. The material that you coat a FL with is called a phosphor, and can be any of a range of materials that emit visible light (different colors depending on the material) when you shine UV light on it. Black lights are just like regular flourescent lamps, but instead are made of a glass tube that is black instead of clear (to absorb bad UV I believe), and it is coated with a phosphor that glows faint purple when exposed to the UV light. With a blacklight, there is both visible light being emitted in the purple frequency (the lowest freq), and there is also a lot of UV light emitted you can not see.
When you shine your black light on a guitar, you are seeing two effects. One is the simple reflection of the visible purple light that is coming off the tube and lighting up the room - and the other is the reflection of the UV light off the guitar, which can ONLY be seen by your eyes if there is some phosphor on the guitar. If there's no phophor on the guitar, you'll only see it normally in the room like everything else that is reflecting the visible purple light. But if there is phosphor, which I assume is in the yellow pigment of the nitro, and possibly in some poly too if it's yellow or otherwise tinted, then you will see glowing visible light due to exposre to the UV.
What I still don't understand is what kind of phosphor is in the nitro lacquer, and how does it react to exposure to sunlight?
When you look at a typical old Fender, the decal is over the finish and somehow protects the phoshor below it. It glows bright compared to the headstock. Protects it from what? From oxidation, from sunlight, something else?
b+). "Blacklight Blue" lamps peak at 365 nm."
