When I learned how to handle printing-out-paper (POP), I realized very quickly that the sun is the best light source, but also very unreliable. Especially in the winter, you will need hours of exposing time and of course, you can only print during the day.
Therefore, I had to design a UV exposure box to get not only reliable but also reproducible results.
Initial thoughts
Based on the size of the collodion negatives I typically shoot, I wanted to print a maximum of 30x60cm negatives. That gives me a paper size of about 50x70cm. My Idea was to build the UV exposure box in a workbench with rollers from IKEA (Bror). A contact copy frame is placed on top, to check the print during exposure. The second question was which UV light source should be installed. There are currently two (feasible) options: UV LEDs or UV fluorescent tubes. Because of the broader spectrum of UV fluorescent tubes, I decided to use the Philips Actinic BL.
To evenly illuminate an area of 50x60cm, I then decided on the 36W variant, the tubes then have a length of about 60cm.
Materials:
- 15x Philips Actinic BL 36W
- 5x Philips HF-P 336
- 30x G13 Bipin Holders
- electronic Timer
- 2-way switch
- input socket with 2-way switch and fuse
- 2x PC-Fan with 220V to 12V converter
- Cables
- T-Splitters
First cabling
First I drew a schematic, a very good help here was the blog of Jose Esteve. I use the 2-way switch to enable two modes of operation, one with reduced power (9 of 15 tubes, 60%) and one with all tubes working. After that, I started with the cabling the Bipin holders & ballasts. This takes a long time but be careful to cable all correctly.
Assembly of the UV exposure box
As soon as all cables were in place, I double checked all for correct wiring and then assembled all in the IKEA workbench. As you can see, I used very thin wood with a white back to cover the sides. The first test of the UV exposure box was successful.
Results
After a few weeks of intense printing on albumen, salt and collodion chloride paper, I am very happy how the UV exposure box works for different negatives. I usually have a first exposure of 30-45min with 60% power and some layers of tissue paper placed between the frame and the unit. A final exposure with full power gives great depth in the shadows.
If you have any questions, please contact me directly.
