The Selenium Experiment

It seems I'm really bad at experiments!

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In all the years I've been printing in the darkroom, I've never done any toning of my prints. I generally prefer straight prints to say sepia toned prints for example. Recently though, I've been reviewing some of my work and found myself wishing the blacks were a touch deeper in several cases. Well, the other day I needed to restock some chemicals and decided to pick up a bottle of selenium toner to try.

Selenium toner converts the metallic silver in a black and white print to silver selenide. Depending on its dilution ratio, the amount of time it is immersed, and the type of paper used, selenium can produce a colour shift in the print from a slight red-brown through to purplish tones. As selenium works "bottom up", that is, it affects the blacks first and highlights last, it can be effective in improving the DMAX (deeper blacks) of the print. Selenium also gives the side benefit of improving the archival properties of the print.

Not knowing where to start I reached out to "The Darkroom" group on Facebook for advice. There are some very knowledgeable and helpful people in that group. Trying to follow their collective advice and suggestions, I put together a plan for an initial experiment...

I found four copies of an old print I made on Ilford Multigrade IV Deluxe RC paper that were all quite close in exposure. I cut three of the prints into three strips and kept one intact to use for comparison. I labelled the back of each print strip with the dilution ratio and time I intended to use.

My plan was to start with a dilution of 1:20 (50ml of selenium to 950ml of water) and immerse the three strips from print one for 60", 90", and 120" respectively. I would then add more chemical to the mixture to increase the dilution to 1:10 and repeat with the strips from print two. Finally, I would increase the dilution to 1:4 and repeat the process. I was aiming to identify which dilution and time combination I preferred and then try that combination on a couple of other prints.

But that isn't what happened...

The comparison print

Mistake #1

I completed stage one no problem. My initial three print strips were floating happily in a water bath. For stage two I intended to add 55ml more selenium to the tray but, for whatever reason, I didn't - I dropped the next three strips straight into the same dilution. Fortunately, I realised straight away what I had done so modified the experiment on the fly. I left the strips immersed for three, four, and five minutes instead. Not what I intended but I figured it would still be worthwhile.

Mistake #2

The original step three idea was for me to add additional chemical to make a 1:4 dilution. I pulled out my phone calculator and figured out that I needed to add 188ml of chemical to the 50ml already in the solution. I have no idea what possessed me but I measured out 238ml of selenium and poured it in, making a roughly 1:3 mixture. Again, I realised my error seconds after it was too late. Oh well. I pressed on and processed the last three strips for 60", 90", and 120".

I feel like all this had been a good plan but the execution was diabolically bad.

The results, such as they are

Despite my bungled experiment I think I gained some valuable information.

The three strips on the bottom left of the above photo are the first set at 1:20. Even after two minutes I can't really see much change in the tones.

The top right set are also at 1:20 for three, four, and five minutes - top to bottom. After three minutes I can detect a very slight tanning in some areas and by five minutes a definite deepening of the blacks.

The bottom right set were possessed at 1:3 for 60", 90", and 120", top to bottom. There really isn't a major difference between the second and third sets. I would say the results of the 1:20 dilution at the longer times are fairly similar in appearance to the 1:3 versions without being as strong. The 1:3 image at two minutes is too much for my taste.

As I understand it, warm tone papers and fibre based paper produce much more dramatic results than RC paper. Next time I print on fibre paper I'll make some extra copies and trial some different dilutions/times again.

A couple of whole prints

Since I already had everything set up I thought I may as well try toning a couple of reject prints from my enormous supply of rejects.

I re-engineered the solution to a 1:4 ratio, correctly this time, and placed in one of the prints. This time I didn't watch the clock, I kept my eye on the print and pulled it out when I thought it looked done. Same thing with the second print. After toning I washed the prints for half an hour or so.

I have to say, I am super happy with the results. The image of the boy on the slide displays a shift towards brown but it isn't overpowering. I think it would have been ideal to have pulled the print out just a few seconds earlier.

The second print has clearly improved after toning, it looked flat beforehand. The selenium seems to have deepened the shadow areas but not touched the highlights. No doubt you won't see it in the crappy phone photo above but it's really added some pop to the print.

I'm looking forward to some more trial and error in passionate pursuit of the perfect print.