BL, BLB.....I'm confused

What is the difference between these two types of bulbs and is one better than the other. The guy at Home Depot said there was a difference but he did not know what.

I want to make a light box to eventually expose for alt processes but i'll be darned if I can find anything to help clear this up. I know very little about light out side of turning it on and turning it off can some one help explain this?

mark said:

What is the difference between these two types of bulbs and is one better than the other. The guy at Home Depot said there was a difference but he did not know what.

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I answer this question in my article at

http://unblinkingeye.com/Articles/Light/light.html

Sandy

I believe that BL stands for Black Light (black coloured glass); BLB stands for Black Light Blue (blue black coloured glass). As far as AZO contact printing is concerned, the BLB emits the right wavelength that AZO is responsive to (so does the BL). I am almost certain that this is the case of alt-processes as well. I am considering a BLB bulb for AZO printing.

On the advice of Ed Buffaloe (www.unblinkingeye.com) I made my UV box out of BL bulbs and that sucker's fast! I print an "all-color" black digital neg in 4 minutes. The instructions that I (mostly) followed at Dead Link Removed say to use BL bulbs.

I have not researched these lights but do they use the same ballast/starter/choke as conventional white tubes ? I have a 'facial solarium' I intend to use for alt.printing and wondered whether I could replace the tubes in it with dark ones.

roy said:

I have not researched these lights but do they use the same ballast/starter/choke as conventional white tubes ? I have a 'facial solarium' I intend to use for alt.printing and wondered whether I could replace the tubes in it with dark ones.

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The answer is yes. Both BL and BLB tubes use the same ballast as regular white light tubes.

BL tubes print about 10% faster than BLB tubes but otherwise there is little if any difference in performance. Visually the light from a BL tube looks rather white whereas the light from a BLB tube has a very dark blue/purple color. The BL tubes themselves are white, while the BLB tubes are medium blue in color from a filter that cuts out all light above about 420 nm. The thing that makes me personally favor the BLB tubes and the reason that I used them in my UV bank is that the very weird light tends to highlight any dust or debris that may be on the printing frame or glass of the easel so I don't have to worry as much about dust. If there is any there I can see it immediatley and wipe it away. This feature of the BLB tubes is more important to me that the slight speed increase I could get with BL tubes.

In general BL tubes tend to cost slightly less than BLBs. On the other hand you can often buy BLB tubes locally at places such as Lowes or Home Depot since they are attractive as party lights.


Sandy King