UV light problem-Bands/stripes in my skies

[Jersey Vic]

I'm getting dark bands across the open skies in my prints that match the orientation of my lightbulbs when using my home made unit. Should I move my prints further away from the bulbs ? Any other ideas?
Thanks
Victor

 

[smieglitz]

Victor,

You don't say which process you aree using but I'm curious as to whether you see the banding printed out or if it only becomes apparent in the processing trays. I've had films band when using other than flat-bottomed trays. Perhaps some alt prints could suffer from the same problem.

If it is a banding caused by the "lightbulbs" (UV fluorescent tubes or ???) , you could also try moving the tubes closer together instead of raising them relative to the printing frame.

Joe

 

[Joe Lipka]

What type of negative are you using? In camera negative or digital negative from a desktop printer?

 

[Jersey Vic]

Thanks for the responses Joe S and Joe L (like Supermans father, right?)
I've been printing cyanotypes using darkroom derived negatives (Bergger 18 ortho & pos/neg process) and the banding becomes apparent in the printing out stage. Moving the prints back 3/4 of an inch has helped alot with no discernable change in exposure and I'll be increasing the distance another inch or so next weekend.
Thanks Again
Victor

 

[Kerik]

Vic,

How far apart are you tubes?

 

[sanking]

The problem could be the film. I experienced a problem with banding with Bergger BPF film when printing with UV processes. The bands do not show on the negative, and in fact don't scan, but when I print them with UV processes they are very prominent. This was 12X20 film developed with rotary processing in a drum. I considered the possibility that the method of development was the reason for the banding, but after a lot of thought concluded that the problem had to be in the film.

Sandy

Thanks for the responses Joe S and Joe L (like Supermans father, right?)
I've been printing cyanotypes using darkroom derived negatives (Bergger 18 ortho & pos/neg process) and the banding becomes apparent in the printing out stage. Moving the prints back 3/4 of an inch has helped alot with no discernable change in exposure and I'll be increasing the distance another inch or so next weekend.
Thanks Again
Victor

 

[Jersey Vic]

Thanks Kerik and Sandy; My unit was made using 4 of these:

http://www.homedepot.com/prel80/HDU...earchResults.jsp&MID=9876&N=2984+4233&pos=n12

Not elegant or super efficient but consistent and no problems up until now. All of bulbs are evenly spaced (1 3/4" or 2 1/4": sounds right..it's upstate now and I'm down) and the lights are now about 6 inches from the print. Here's the kicker- looking back at earlier prints of this negative that I made with a far better 'engineered' unit 'the problem' was noticeable-though far less so- because I printed it much lighter and split toned it. Couple this with the fact I noticed this issue with another Bergger BPF 18 negative and I think it comes down to Sandy's explanation-it's the Bergger film (tray processed)