Question about black light blue flourescent tubes?

[scootermm]

Okay I have a rather odd question and am not sure whether its something to be concerned with or not.
For a couple years now I've been using a bank of (8) 48" 40Watt T12 Flourescent Black Light Blue bulbs in a homemade UV box for my alt process printing.
Last night I had two bulbs go out on me. I found a place locally that sells them, so I bought some replacements.
The question I have is that apparently BLB bulbs come mostly in the T10 diameter as opposed to the T12 diameter.
They are still 40watt bulbs and BLB, but I'm wondering if the UV output will differ greatly if I replace the two burned out bulbs with 2 of the T10 bulbs.
Basically having a bank of 8 bulbs where 6 are T12 and 2 are T10. My thought is to put the T10 bulbs on the outside edges of the full 8 bank of bulbs.
Apparently most manufacturers are going to the T10 diameter because its more efficient and they still work in the same ballasts/fixtures as T12 bulbs.

May not be a big deal and the smaller T10 diameter might just make it easier to put the bulbs in

 

[Monophoto]

You might want to poke around this site - it will tell you more about light bulbs than you want to know. Dead Link Removed

I couldn't find anything that was specific to black light bulbs, but there is enough about T12, T10, and T8 bulbs to lead me to suggest that the only good answer will come from the manufacturer of the bulbs. It is pretty clear that there are potential changes ("performance improvements") in going from T12 to T10, and some of those clearly could affect UV output.

By the way - relatively useless factoid of the month - the T number is the diameter of the tube in eights of an inch. So a T12 is 1.5 inches, a T10 is 1.25 inches, and a T8 is one inch.

 

[scootermm]

Thanks Louie.

 

[nworth]

Different brands may use slightly different phosphors and filters, and they may produce somewhat different light. It's just like the situation with standard cool white lamps - you can pick out different brands in a fixture. For consistency, it's best to keep all the tubes the same - same manufacturer, same kind, and same age. BLB bulbs may be a bit less effective than BL lamps because the paper is sensitive to the blue light produced by the BL lamp as well as UV, but the blue is filtered out by the BLB filter. You can get a rough idea of the evenness of the light by moving a fluorescent target around under the lights. Ordinary paper with UV brighteners will work.

 

[Mike Wilde]

next factoid - the latest skinny tubes I am designing with are T5's, and man, do they allow shallow luminares to be designed. The balast needed to make them light is another complexity issue though. I am not aware of anyone coming out with them in UV options so far. Production is just starting in North America, coming over from Europe.

 

[scootermm]

just an update to the initial post.
I placed the T10 bulbs on the outer most edges of the 8 bank UV box.
I printed 4 12x20 palladium prints last night and cannot notice any observable difference.
The bulbs did "look" brighter and more blue.
But there wasn't a visually discernable difference.

 

[FredW]

Thanks, that's good to know. When it comes time for me to get new bulbs.