SILVER MIRROR PRINTS

No colour.........no reversal.........environmentally friendly prints.......

John Pearle (Area 13)

An article in the January / February issue of the American magazine, Photo Techniques, described a new technique which produces what were described as Silver Mirror Prints. The author, Professor W.L. Jolly, has done a great deal of work over the years on the principles and practices of solarization and related techniques, but this process appears new. It produces prints in which the non image parts are not the base white but are reflective silver. When conditions are right, the results should be spectacular.

We have been trying out the process and the details here are based on what has been done so far. This may encourage other CRC members to experiment with the process and to this end recipes based on Prof. Jolly's article are given. These are suggested starting points, much improvement on our results is obviously possible.

The principle is simple. Ordinary black and white paper is used and exposed normally. A high contrast image is developed in a first developer which is more or less conventional. Then the undeveloped silver halide ( the white parts of the print) is converted to metallic silver using an energetic second developer which contains thiocyanate as a silver halide complexing agent. A sort of fogging physical developer. We have had a few problems getting it to work however.....

First, some background - skip this if you just want to find out how to do it, go to The Recipe. The original article gives a method and recipes. However Prof. Jolly uses some proprietary Kodak chemicals which might cause some problems. They are:-

Dektol. A readily available paper developer. Used by Prof. Jolly as a component of the second developer. Unfortunately the US version of Dektol seems to be different to the UK version. To add to the confusion, there are two UK forms, and three names. There is a similar variety in the US types. I won't go into the details of these here but in essence the US versions are MQ developers but the UK versions use hydroquinone only. So the Dektol we buy won't be the same as that used by Prof. Jolly and may well give different results.

S2. Kodak actually call this stuff Activator SII, and it is basically sodium hydroxide solution. It is made for machine printing processes using developer incorporated paper - like Kodabrome. It's really a commercial graphics item and our local photo dealer told us it wasn't available in the UK. The stuff is made in France so I don't believe you can't get it but we haven't tried further.

As a result of all these confusions we have gone back to basics and produced a recipe which is as close as we can get to Prof. Jolly's using chemicals you can easily get. It can produce good results "as is" and will serve as a good basis for experiments. He recommends Kodabrome ll RC paper grade 4. We have not tried any others. This is a developer incorporated type. Others would behave very differently.

The Recipe

First Developer.
Metol ................................................................................... 3.1g
Sodium sulphite .................................................................. 25g
Hydroquinone ....................................................................... 2g
Sodium carbonate (anh) ..................................................... 43g
Sodium bromide ..................................................................... 2g
Water to ................................................................................. 1 L
Dilute 1 + 1 for use.

Second Developer.
This is made up of four components

D72 (Dektol Substitute) .............................................. 95 parts.
First developer ............................................................. 65 parts.
Sodium Thiocyanate 5% ........................................... 185 parts.
Add before use

Sll Substitute 155 parts.
Use this within a few hours of adding the Sll (hydroxide) solution.
It is important that the D72 and first developers used here are not oxidised, keep the air away from them, otherwise there will be fog on the final print.

The recipes for the D72 and Sll components are as follows:-

D72
Metol ....................................................................................... 1.5g
Sodium sulphite ................................................................... 22.5g
Hydroquinone ........................................................................... 6g
Sodium carbonate (anh) ......................................................... 40g
Potassium bromide .................................................................... 1g
Water to ................................................................................ 500mL

Sll (substitute)
Potassium hydroxide ............................................................... 50g
Sodium sulphite ........................................................................ 50g
Potassium bromide ..................................................................... 5g
Water to ................................................................................. 500mL

You will also need a normal acetic acid stop bath, and a hardening fixer.

Procedure (@20°C)
Use a safelight appropriate for the paper.

First developer ............................................................................30s
Drain ............................................................................................ 10s
Second developer 60 - 90s Agitate vigorously for the first 35s.
Stop ...................................................................................... 30 - 60s
Fix ......................................................................................... 15 mins
Wash ................................................................................... 30 mins.

Solution Capacities

In his original article, Prof. Jolly suggests replenishment methods for first and second developers. We have not tried these.

The first developer seems to go on for ever. If you keep the air out of the bottle with an inert gas it just keeps going. Eventually it gets so black (not brown, like oxidised developer, but black as if it has a metallic powder suspended in it) that I lose my nerve and throw it out. The limiting factor is probably fog. It must produce clear white areas.

The second developer will process from five to seven 10 x 8 prints per 500mL. When the silver areas show a noticeable grey veil when the print is in the fixer, it's done. In common with other caustic developers, the working solution does not keep well, so use it within a few hours. We haven't done any tests to find out how long it will last, but if you make it up in 500mL lots there is no need to store it. In use it accumulates a brown suspended "fluffy" sort of material, presumably the silver thiocyanate complex. If excessive, this indicates too much thiocyanate, but seems to do no direct harm.

The stop bath gets the most punishment. The second developer is strongly alkaline so the acetic acid doesn't last long. Replacing about 100mL with fresh solution for every five prints seems to work. We have been using an indicating bath and replacing it all when the indicator looks pale. A rinse after the second developer would prolong the life of this bath but this has not been tried. (I haven't got room for another tray).

The fixer should last a long time. Remember that the silver halide usually removed here has, in theory at least, all been converted to metallic silver. We haven't done any tests on this. Good news for the environment, bad news if you collect silver laden fixer.

The first and second development steps can, with practice, be done by inspection. Be careful not to print the image too light, good solid blacks show up best. The whites must be clear for a good silver finish. Remember that the silver will appear in the white parts of the picture and will lower the apparent contrast depending upon the viewing angle. The silver layer will appear after about 30 seconds, if you get the viewing angle right you can see it under the safelight. It look better under this light than it will when dried.

Handle the print with great care, especially when wet. Don't touch the surface with anything. Make prints with borders wide enough to keep fingers away from the image area. When dry, there will probably be a deposit of silver powder on the print surface. This will be worse if the D72 or first developer used in the second developer have oxidised. This can be gently brushed off. Depending on how the second developer has behaved, the silver layer may be dull with a slight bronze effect when seen from certain angles. This can be removed by gently polishing the surface. Do this with great care, the surface is easily scratched.

When finished the print surface is easily marked, greasy fingerprints will not come off completely. Also remember that the surface is silver and sooner or later will start to tarnish so must be protected. Laminating or coating with lacquer should work to keep air and fingers off the surface.

The Process

Professor Jolly gives some explanation of how the process works, this is my interpretation, as a non chemist, based on what appears to be going on when the process is used.

The initial image must have good solid blacks since the silver deposited in the white areas will appear to lower the contrast, and clean whites, since it is the non-image silver halide which will form the metallic silver.

There must be very low fog. Any produced by the first developer may act as nuclei for the second developer (as in physical development) and be amplified by it.

As you would expect, the key to the process is the second developer. It consists of a very active high contrast caustic developer and a silver halide complexing agent - sodium thiocyanate. This provides the source of silver for the developing agent to work on. The metallic layer appearing to be formed at the interface of the emulsion and it's support. There is therefore a balance between the rate at which the complex is formed (silver halide dissolved ), and the rate at which it is used by the developer. If the complex is not formed fast enough, the developer will reduce the silver halide still dispersed in the emulsion, and the silver layer that is formed will be overlaid by a light grey fog. I this happens, try increasing the thiocyanate. If the complex formation is too rapid, it may diffuse away from the interface. This results in the silver metal being formed in the bulk of the emulsion giving a "satin" like look. If this happens try reducing the thiocyanate.

For the Future

More work needs to be done identifying problems and documenting cures. Apart from the second developer we have not determined the processing capacities of the solutions. There is the use of organic anti-fog agents to be tried in both developers ( this gave mixed results when I tried, it seemed to alter the appearance of the silver) . The somewhat odd method of making up the second developer from four components could be tidied up (we have done some of this but again with mixed results). The process also needs to be tried with other paper types.

Methods for protecting the prints also need to be tried. Cellulose lacquer applied with a brush does work but it is very difficult to get a good surface. Laminating should work but you need to have access to the equipment to do it properly.

The process is capable of producing remarkable results on the right subjects. I hope that other CRC members are encouraged to try this and related processes out. It's not colour and it's not reversal - the confession of a heretic.

April 1999.