Safelight Testing

[David Ruby]

I guess I should stop what I'm doing and finally test my safelights now that I have both of them installed where I want them. I am using two simple Kodak screw in safelights with OC filters, mounted at least 48" from my enlarger base board and my developer tray. (I was to anxious to get printing after months of work to test them first!, and I seem to be getting pretty good results so far.)

I've read numerous ways to test for safelight fogging. Some sound easy, some very laborious. What have some of you done to test your safelights? Would you recommend one method over another? Thanks.

 

[lee]

David,
The method I use can be done pretty quickly. Make a test print without the safelights on and process the paper. Find the time that is minimal exposure. Make another print using this time this exposure time with the safelights still off. Now turn on the safelights and without removing the paper from the easel cover about half the paper with a card stock and leave it there for about 5 minutes. Then process the paper. Compare the two sides of the paper. If you are safe, there will be no difference in either side. You might consider running another at about 8 minutes to see where you start to fog.

You need the minimal exposure to excite the paper and get a more accurate assessment. Fog is generally seen in the highlights and make the print look dingy. If you pass the 5 minute test, there are several other things that can cause a print to look dingy. Let's go with unsafe safelights first.

lee\c

 

[dr bob]

I use a variation of Lee’s method. I place a small strip of paper on the enlarger easel and cover half of it with an opaque object (my dodging/burning card). I leave it exposed to the safelights for about 5 minutes. Then I remove the object and place a coin on the covered/uncovered line of demarcation. Leave this for another 5 minutes then develop “normally”.

The “theory” is that a small number of photons light will sensitize the emulsion making additional exposure easier. If there is a problem, shadows will be evident beneath the coin as expected.

Hope these suggestions help.

 

[john_s]

If you use VC papers, test your safelights with each paper that you use. They are all different. Forte papers (at least some of them) are more sensitive.

I have settled on 660nm LEDs for safety, even though the very red light is not good for evaluating prints.