zone vi cold light head issues ... any insights ?

hi

a friend of mine has a zone 6 cold light head ... it is one of the ones with 2 bulbs ..
he regularly enlarges to 16x20 without any issues but recently he has been making mural sized
images and noticed a dark vertical stripe that runs down his print ..
( he says the stripe doesn't extend into the margins of the paper so its not the paper ... )


zone 6 or aristo dual bulb users any idea what this might be ?

is there a place to get replacement bulbs if it is the bulb, or a way to "fix" this problem?

thanks !
john

Rotate the head inside the collar and see if the strip also moves.

Make a low contrast print and high contrast print to see if one bulb is at fault.

Inspect the plastic diffuser.

Perhaps something changed in the darkroom and there is an enlarger column reflection locally darkening the print.

With mural prints, darkroom light leaks can become an issue.

I would be looking for stray light or reflections.

hi ronald:

i forwarded your reply and suggestions to him
and he figured out what was going on ...

... it was stray light beam from the head not sealing well

thanks for your help and suggestions !

john