DIY UV lightbox - to reflect or not to reflect...

I am slowly acquiring all the bits to create a DIY UV lightbox for alt process printing. The box I am using is a fairly shiny ikea kuggis. I am unsure as to whether I should line it with something matte black to absorb any stray light reflections thereby ensuring all the of the light that hits the paper is coming directly from the LEDs or to line it with something very reflective like foil in order to maximise the amount of light hitting the paper and potentially shortening exposure times.

Any thoughts?

If you're going for led strips, then the light at the print surface will be semi-diffused already. Adding some reflection will gain you a small amount of light (not much) and otherwise not make a huge difference.

For prints on paper, provided you've got a good contact frame, diffuse light is generally not a problem. It's not ideal or sometimes even catastrophic in very specific use cases, especially thick-media processes combined with halftone screen negatives (e.g. carbon transfer using image setter negatives). However, for your typical cyanotypes, salt prints etc, a box with LED strips will work perfectly fine.

So all considered it's something I wouldn't spend much time or resources on to figure out. It just doesn't make much of a difference.

alexreltonb said:

I am slowly acquiring all the bits to create a DIY UV lightbox for alt process printing. The box I am using is a fairly shiny ikea kuggis. I am unsure as to whether I should line it with something matte black to absorb any stray light reflections thereby ensuring all the of the light that hits the paper is coming directly from the LEDs or to line it with something very reflective like foil in order to maximise the amount of light hitting the paper and potentially shortening exposure times.

Any thoughts?

Click to expand...

My home-made box is painted glossy white inside and out. It initially had fluorescent bulbs but was retrofitted, some years ago now, with 495 nm LED strips. No complaints about the prints from either iteration.

Okay great, thanks. I think I'll just leave it unlined for the first iteration then.

alexreltonb said:

Okay great, thanks. I think I'll just leave it unlined for the first iteration then.

Click to expand...

I just recently went through the same process, initially constructing a nice box with white painted interior and actually found whilst evenly illuminated, it was too bright with the LED array 30cm above the base. I was seeing Traditional Cyanotype exposures of about 30 seconds.

So I ditched the nice painted box and just hung the fixture under a bench at about 60cm distance from the printing frame which worked out at about a 4 min exposure for Cyanotype (inverse square law and no side wall reflection, etc).

I'm using a couple of 50W 395nm UV panels from Amazon.

I'd just set up something quick and dirty and then run some test strips with whatever process you're starting with.