building an exposure unit

[strangedesign]

im planning on building an exposure unit and ive been searching through the forums for some answers but cant seem to find any.

i have 48" fluorescent fixtures with the unfiltered UV bulbs.

i will probably make the unit around 50" x 30" or so.

my questions are:

1. How far should light fixtures be apart from each other?

2. How much space between lights and screen?

if any other bulbs work better then the unfiltered UV, i could always use those

This is my first post here, i just joined the premium section. thanks for the help!

[clinttw]

kudos to you for going premium!

I think I had a process for building a shop from scratch on here, here's a link with basically the same info. It may not go into too much detail about how to build the exposure unit but it might give you an idea of how we did it in Tim's garage. It was fairly easy and cheap and works great.

INSIDE THE ROCK POSTER FRAME: Tim Doyle of Nakatomi and How to build an entire silkscreen shop for under 2K.


Welcome to the forums.

[mikeage]

Whoa, it's like I'm in bizzaro world: up is down, black is white, blonde is straight, new people go premium and vets offer help. I like it here.

[strangedesign]

thanks for the responses guys. thanks for the link, i saw it before but must have overlooked it.

im thinking 4 fluorescent fixtures should do the trick in a 50 x 30 box. what do you think?

[strawberryluna]

I have my fixtures about 3" apart, I think? And I've seen some as far as 6" apart too, anywhere in that range should be good. I'd keep the light about 6" - 8" below the glass too and you should be fine.

way to go starting out with class here!

[strangedesign]

thanks strawberrylune. i just want to make sure i dont get light bands and overburn or underburn some spots

[sixtybones]

Here is what I built. Everything but the bulbs were from the Restore (thrift store for building supplies). It was about $150 for everything. Whatever you build, use an exposure calculator. Makes life easier.
http://i.imgur.com/R3N9G.jpg

[Andymac]

very nice.

I think Jeremy Wilson and maybe some others added a vacuum lid to theirs - 3mm close cell neopreme used in wetsuits, attached to the bottom of a hinged frame that sits and clamps (eyehooks or similar) to the bottom section, and a valve made from pvc pipe you can hook a vacuum cleaner to.

If you notice visible thick and thin waves on your emulsion after exposure and washout, you need to (a) move the bulbs closer to each other in an evenly spaced pattern, or (b) move the bulbs away from the glass. or a combo of the two. We use 'super actinic' bulbs in our factory made units, they work pretty well (Delicious Design, Black Swan, Caughtin Customs, Burning Bones Press, John Brown University, Ryan Burkhart all have these flourescent UV bulb units)

[strangedesign]

i went to lowes to day to look at some light fixtures. due to my lack of space im going to be using 24" tubes. i know its probably smarter in the long run to make it bigger, but i just cant.

the dimensions will be around 26" x 26".

ill be using four 2 light fixtures, so 8 total bulbs.

before i buy the bulbs, are these the correct ones.... GE 10244 - F20T12/BL - 20 Watt - T12 Linear Fluorescent Tube - Black Light | 1000Bulbs.com

[Andymac]

looks like they work according to the comments.

generally, the UV output in the 330-440 nm range (what you want to expose with) Blacklight<unfiltered blacklight<super actinic

the ones we use come from aquarium supply places (or that's what they use them for, also tanning beds)