Convert Porta-Trace lightbox to alt process UV source?

Hi everyone,

The local art-supplies store is having a sale on 10x12" Porta-Trace lightboxes. It occured to me that it might be possible to open one of them up, replace the stock tubes with fluorescent BLBs, remove the translucent plexiglass top, and use it as an alt-process light source (inverted and resting on top of a printing frame). After all, they are designed for even illumination...

The advantage here would be that the fixtures and electronics are already in place. The challenge is knowing whether the tubes used in these lightboxes are a standard size/shape (i.e. are BLBs available in that size?)

Any ideas?

check the Porta-Trace website for replacement bulb specs. If they use a standard bulb, they should state what it is. Then go check the Home Depot website AND some lighting suppliers websites for that bulb size. I found a good variety of BLB bulbs at Home Depot that were not necessarily listed on their website, and vice versa. To make my own UV lightsource, I just bought six of these GE black-light fixtures they had (the cashier must have thought I was planning an industrial pot farm, or one hell of a rave party). The GE fixtures are about two dollars more than the bulbs alone, and come with cords, ballasts, and switches. To complete the rig, I tossed in a six-outlet surge protector which then plugged in to an old Gra-Lab digital enlarging timer I have which can set time up to 99 minutes. The whole rig (six fixtures, surge protector) set me back about $100-125, and I get nice even exposures on up to 12x20 print sizes, and my exposure times run in the 6 1/2- 7 minute range. They usually keep the GE blacklight fixtures in the same rack as the grow lamps and the under-the-counter fluorescent fixtures. If you have the room for it, a set of these fixtures will cost you the same or less than some porta-trace units, but give you faster exposures and more working space so you could in theory anyway cook two at a time.

Ok- so my solution won't be as cheap as the porta-trace. But your print times with it will be PAINFULLY slow... the 10x12 uses one 8w bulb. The rig I describe has 6 15w bulbs. The working distance you'd need with the porta-trace unit to get print times with palladium under 30 minutes would probably mean you'd have banding in your exposures. Part of the way they achieve their even illumination is through that frosted plexi top, which totally kills any UV you would pump through it.

BTW- the prices I quoted above are USD prices.