Deliberations on building a UV light box

[Tom Kershaw]

Using Jean-Bernard Roux's article on building a UV exposure unit as a starting point, and along with Sandy King's various contributions, I've been planning the construction of a UV exposure box.

My intention is to use twelve 24" black light blue fluorescent tubes installed in close proximity to each other. In Jean-Bernard Roux's article he places the ballasts and wiring etc. on the other side of the board to the tubes, which seems a sensible option.

I managed to find separate 'T8' tube sockets and 2 x 18W ballasts which should reduce any excess unit size. My plan is to paint the inside of the plywood white and varnish the outside.

Ballast:
Dead Link Removed

'T8' tube sockets:
http://www.firstlightdirect.com/scp...lasts_End_Caps/Fluorescent_Tube_End_Caps.html

Wiring the ballasts to the tubes is done in something approximating my following diagram as far as I'm aware:

This would be repeated six times to cover all twelve tubes.

Maplin sell this fan (120mm model): Dead Link Removed which looks suitable for cooling purposes.

French article:
http://www.galerie-photo.com/construire-insoleuse-uv-photographie_roux.html

I was planning on the black light blue tubes being situated approx. 120mm from the print surface / contact printing glass, is this a sensible distance?


Tom.

 

[Davec101]

I was planning on the black light blue tubes being situated approx. 120mm from the print surface / contact printing glass, is this a sensible distance?


Tom.

I have my BLB's 150mm from the print surface and get good coverage, am sure 120mm would be fine also.

 

[Colin Graham]

I used 10 24" tubes spaced about 20mm apart, which used to illuminate a 50x60cm area very well. At first it the contact frame was around 120mm from he tubes, but then I made a vacuum frame that brought it to around 90mm. Still very even across the bulbs, but the ends of 20" long prints have to be burned in slightly, even with 24" long bulbs. I might make an extension to mount the vacuum drawer in to get the extra distance back.

 

[Tom Kershaw]

Colin,

Which alternative process are you printing in your unit? I know David Chow prints cyanotype and pt/pd.

Tom.

 

[Colin Graham]

Sorry, should have mentioned that. Kallitype and carbon transfer, a bit of albumen as well.

 

[Tom Kershaw]

Colin,

Thanks. I'm also considering a HID lamp system which I posted about on the Bostick & Sullivan forum but haven't received any feedback yet.

Tom.

 

[Colin Graham]

I'm following that as well. Many of the industrial fixtures seemed to have a longish warm up time when I was building mine, that's what made me decide on a blb unit. Seemed like the best all around compromise at the time.

 

[Tom Kershaw]

I suppose the unit could be left on, the tissue only exposed when ready. I would be installing the HID system in a separate room adjacent to the darkroom, so could possibly get around the issue of UV exposure.

Tom.

 

[Trevor Crone]

Tom, this may be of interest to you?

http://www.lightbulbs-direct.com/product/2136/ultra-vitalux-300w-uv-reflector/

 

[Tom Kershaw]

Tom, this may be of interest to you?

http://www.lightbulbs-direct.com/product/2136/ultra-vitalux-300w-uv-reflector/

Thanks for the link Trevor, I had spotted that. I'm following the thread on the Bostick & Sullivan forum re: HID lamp systems, which has now generated some very helpful responses. Some indicate that 400 watts would not provide particularly short exposures, and encourage the use of higher wattage systems.

Tom.

 

[Vaughn]

I have already posted on the Carbon Forum, but I'll put this here also as a high-power alternative for alternative printing.

http://www.bulbman.com/index.php?main_page=product_bulb_info&cPath=5387_8870&products_id=10940

I actually use the 450W equivilent, with carbon printing exposure times of around an hour for non-staining developed negs. I don't mind the hour exposure times -- I can work with two different negs at a time. While one is being transferred and then developed, another neg is being exposed. And these lights are cheap enough to get two seperate systems going and that would keep one constantly working...no waiting for a tissue to be done exposing. I would not use the 450W for anything over 8x10 -- the 750W might work well with larger negs than that.

I personally would not use a bank of BL (or BLB) tubes for carbon printing -- the diffuse light would soften the image far too much for my taste -- I want carbon prints as sharp as the negative.

Vaughn

 

[Jim Noel]

I have two UV units. One consists of 24 inch BLB as close together as possible, 30 mm from the surface of the printing frame. There is no banding and I have used this unit for many years. The second unit is an HID lamp of 1000 W. I started with a 750 W unit, but this was too slow for me. The 1000 W unit provides times equivalent to the sun on a bright day in July in San Diego. I print almost all processes with one or both of these units.

 

[Tom Kershaw]

Vaughn,

I've made another post on the Carbon forum relating to a different type of integrated ballast 160W metal halide BLB lamp that could be used in a grid arrangement.

Tom.