Lexy Xiao finds alternative ways to do the silver mirroring toning without the commercial toners which are mostly discontinued today. She shares her recipes and process here.
WARNING: This is for experienced and advanced users only. Read the safety sheets before attempting to use chemicals and use the correct safety equipment. Hazardous chemicals are used.
A little knowledge about silver mirroring
Silver mirroring looks like a reflective metallic sheen. It is a chemical deterioration mostly appearing on the surface of silver gelatin based B&W historical photographs, due to three factors in the storage environment: acidity, humidity and the electrostatic force. The acid in the presence of humidity causes the transformation of silver into silver ions (oxidization). The silver ions are driven by the electrostatic force to the surface of the emulsion and then are neutralized on the surface (Mestre, Vergés and Udina, 2018). The reactions produce a reflective metallic sheen which can be observed under oblique light. The sheen can be seen as in reddish, bluish, greenish, golden, bronze colours, etc.; bronze is the maximum reaction. The effect is recorded in a chapter as The silver bronze mirror toners in The master photographer’s toning book by Tim Rudman.
Short videos to understand the silver mirroring effects:
This article is for carrying out the silver mirroring toning without the commercial products, just in case all of them are discontinued in the future. I managed to create my alternative recipes and processes to make the silver mirroring as the unique visual effect for my prints, bringing the silver back to the surface, and the deterioration back to the artwork. The visual from my recipes and processes present a colourful reflective metallic sheen or a tarnished silvery layer on the top of the image. Silver mirroring is a mesmerizing effect that the viewer has to look at in reality; I do not want us to lose the ways to produce it, and only achieve it by chance. Thus, I share my two recipes and the processes here, so that more people will know how and try it out; also, it ism meant for further development of this technique.
For each recipe, there are two ways to do the silver mirroring toning. Direct silver mirroring toning happens on the highlight areas before the fix bath; indirect silver mirroring toning happens on the shadow areas after the fix bath. Think about the images that you would like to test for the different types of toning.
Abbreviations of formulas
- potassium hydroxide = KOH
- sodium hydroxide = NaOH
- potassium thiocyanate = KSCN
- Copper(II) chloride = CuCl2
VERY IMPORTANT: Label everything CLEARLY when doing the preparation; read MSDSs of the chemicals before the experiment; wear safety equipment for ALL the experiments.
Materials and chemicals needed
- Ordinary black and white darkroom chemistry; I applied Ilford developer and rapid fix, diluted acetic acid for stop bath (can also use ready-made stop)
- Gelatin silver paper; I applied Ilford RC pearl; other RC and FB papers can also work but need experiments
- KOH flake; I applied a 90% concentration (recipe 1, direct and indirect toning)
- KSCN flake; I applied a 98% concentration (recipes 1 and 2, direct and indirect toning)
- CuCl2 Solid; I applied a dehydrate of the compound (recipes 1 and 2, indirect toning)
- NaOH Solid; I applied caustic soda drain cleaner; make sure the ingredient is only NaOH (recipe 2, direct and indirect toning)
- Ammonia liquid; I applied 9% ammonia cleaner; make sure the ingredient is only ammonia and water (recipe 2, direct and indirect toning)
- Sodium thiosulfate anhydrous or pentahydrate solid for hypo fix bath; I applied pentahydrate solid (recipe 1 and recipe 2, direct toning)
- Trays and tongs
- Measuring cylinders and jars
- Masking tape and pen for labeling the chemicals
- Non vented goggles and fume mask against ammonia; I applied 3M ABEK 1 filter for the mask.
Silver mirroring toning Recipe 1
Applying KOH and KSCN, developed from my chromo recipe, without an ammonia smell.
- Activator stock: 10% KOH solution; add 30 g KOH flake to cold water to make 300 mL solution in total; be careful as the dissolving process can give off a lot of heat. The stock can stay on the shelf for a long time.
- Stabilizer stock: 20% KSCN solution; add 60 g KSCN flake to cold water to make 300 mL solution in total. The stock can stay on the shelf for a long time.
Keep the KSCN away from any acids; contact with acids liberates very toxic gas!
- Chromo toner:
1:1:1=Activator stock: Stabilizer stock: working strength developer; e.g. get 100 mL activator stock, 100 mL stabilizer stock, 100 mL working strength developer to make a 300 mL toner in total.
- Hypo fix bath: sodium thiosulfate solution; for the anhydrous compound, 3:20=the amount of the compound in grams: the total volume of the solution in mL, e.g., get 150 g compound to make a 1 L solution in total; for the pentahydrous, 6:25, e.g., get 240g compound to make a 1L solution in total.
- KSCN stabilizing bath: 1:120 KSCN solution;
Method 1: get 12.5 mL stabilizer stock in a measuring cylinder and then add cold water to make a 300 mL solution in total (refer to the following formula to reach a desired amount of the solution: Aimed dilution x desired amount of stabilizer in mL÷the dilution of the stock; e.g., 1/120 x 300 mL÷20% = 12.5 mL).
Method 2: add 4.2g KSCN flakes to cold water to make a 500 mL solution in total.
- CuCl2 bleach: 0.7% CuCl2 solution; add 2.8 g to cold water to make 400 mL solution in total.
PS. Chromo toner, Activator and Stabilizer waste can be collected in the same waste container as the chromo mixture for future use; you could mix old chromo mixture and developer stock to make new toner, e.g., 290 mL chromo + 10 mL Dev; if not working, add more Dev and warm the toner up.
Silver mirroring toning Recipe 2
Applying NaOH and ammonia, inspired by the Rockland Halo-chrome toner and silver mirror reaction by Tollen’s reagent, with an ammonia smell. Carry out the process in good ventilation area, wear gloves, non-vented goggles and a fume mask.
The percentages of the ingredients for the toner are 4% NaOH, 8% ammonia liquid, 2% developer stock, and warm water to the desired amount; e.g. make a 300 mL toner:
- Add 1.2 g NaOH solid to 50 mL room temperature water in a jar; be careful as the dissolving process can give off a lot of heat.
- Add 24 mL ammonia liquid to the solution.
- Add 6 mL developer stock to the solution.
- Add warm water to 300 mL, and place the jar in a hot water bath to keep it warm
PS. Make the toner just before use, at least mix the developer stock and warm water; from my experiments, this toner can only last around 1.5-2 hrs, but it also depends on how many and how large the prints you are making during the time. The colour of the toner will turn darker while doing the toning. Dispose of the waste as developer.
Process: Direct silver mirroring toning
- Prepare a developer tray, a toner tray (use just enough solution to cover the bottom of the tray for the toner; e.g., 4×5 inch print in the 25x20cm tray, applying 200 mL toner; 8×10, 37.5x32cm tray, 300 mL toner), a hypo fix tray, a KSCN stabilizing tray, and a large tray or tank of water for rinsing.
- Warm the toner up to 30-35°C by hot water bath.
- Make an ordinary exposed print with a medium or higher filter by the enlarger.
- Do everything in the safe light.
For Recipe 1: develop it for 50 seconds, just about the latent image becomes clear; it can be longer when the developer gets less fresh.
For Recipe 2: develop it for 2 mins.
- For Recipe 1: immediately remove the print from the developer and immerse it face up in the toner, then immediately turn on the white light, and vigorously and constantly agitate the toner tray; the highlights will get darker or into other colours; about 1 min, the mirroring on the highlights and Sabatier with Mackie line can be observed; after 3 mins, no obvious change.
*The mirroring can also happen when you do the process in safe light, but sometimes it is not very strong.
For Recipe 2: remove the print from the developer and immerse it face up in the toner tray with vigorous and constant agitation. About 1 min, the mirroring on the highlights can be observed in the safe light; after 3 mins mostly no obvious change.
*The white light can be turned on to observe the mirroring after the mirroring is formed; there would not be huge changes in a short period of time.
- When the colours and the sheen are desired, immediately remove the print and rinse it for 1 min; everything can be done in white light from the rinse.
- Place the print in the hypo fix tray for 5 mins.
- Rinse the print for 1 min.
- Place the print in the stabilizing tray for 5 mins.
- The final rinse of the print, RC for 10 mins.
- Dry it on the rack/ screen/ shelf; room light is OK.
Conclusion and suggestion – Direct silver mirroring toning
- RC paper is easier than FB to work with.
- High contrast images work better.
- Higher temperature of the toner works faster and stronger, easier to get the bronzing effect, e.g., 40-45°C.
- Do not touch the mirroring surface when the print is wet; it is easy to remove the mirroring by rubbing; when the print has dried, the mirroring is stronger, but gloves are required to avoid fingerprints.
- Do not wipe the surface unless it is necessary; gently wipe the surface with a dry soft cloth (e.g., silk) to remove dust or grease; do not apply for removing any liquids.
- Printing with a filter can help the formation of silver mirroring; higher filter, like 4, works well.
- Black silver dot stains grow on some of the prints that I did not stabilize; it is my idea that the stabilizing bath prevents the stains from happening. The stains could be silver sulphide, formed by reactive silver ions reacting with atmospheric hydrogen sulfide or the decomposition product of thiosulphate (Baines, 1970). It is important to keep the hypo fix and the stabilizing bath fresh, and wash the print using a good balance—neither excessive wash nor lack of wash.
- For recipe 1, apply different strengths of the developer in the toner (e.g., lower strength), to get different colours for the mirroring; I tried 50%, 80%, 100% strength of the developer; all work well but differently.
- For recipe 1, the mirroring can also be achieved by Chromoskedasic painting, referred to my article Self-made activator and stabilizer for Chromoskedasic painting. By gently rubbing the back of the print on the sink (or another material), and making sure the whole surface of the print is covered with the liquid, this would help the formation of the silver mirroring. My deduction is the action causes the electrostatic force, driving the silver ions to move to the surface of the print.
- The different colours with/without the sheen are based on the exposure light for doing the printing, the first development time, the strength of the developer, and that of the toner. Thus, experience and notes from experiments are important ways to know how they could work.
- Bronzing mirroring effect can stay after rapid fix, but rapid fix can fade other colours.
Process: Indirect silver mirroring toning
- Prepare a high contrast, well fixed and washed print; Ilford Rapid fixed print and hypo fixed print can both work.
- Prepare a CuCl2 bleach tray, a toner tray (use just enough solution to cover the bottom of the tray for the toner; e.g. 4×5 inch print in the 25×20 cm tray, applying 200 mL toner; 8×10, 37.5×32 cm tray, 300 mL toner), a KSCN stabilizing tray, and a large tray or tank of water for rinsing.
- Warm the toner up to 30-35°C by hot water bath.
- Immerse the print in the bleach with constant agitation, until there is only a yellowish ghost image; do not let the print stay in the bleach too long, e.g., over 15 mins; it will probably make the toning fail.
- Rinse the print for 1min.
- Immerse the print in the warmed up toner with rigorous and constant agitation; the colour of the print will immediately turn darker. In about a minute, the reflective or tarnished silver mirroring on the shadow areas can be observed; after 3 minutes, no obvious change.
- Remove the print from the toner and rinse it for 1 min.
- Can be fixed again by hypo fix for 5 minutes and then rinse for 1 minute, but I did not do that.
- Place the print in the stabilizing tray for 5 minutes.
- The final rinse of the print, RC print for 10 minutes.
- Dry it on the rack/ screen/ shelf; room light is OK.
Conclusion and suggestion – Indirect silver mirroring toning
- It is the same with the first five conclusions and suggestions from the direct toning.
- Do not do step 8 by rapid fix; the tarnished mirroring will disappear, and the image can be irreversibly bleached; if you prefer a brownish image with the reflective mirroring (it can happen sometimes), try the rapid fix treatment in a controlled short time period.
- It is possible to repeat 4-7 steps for a second or third time, if for some reason the mirroring is not strong enough (e.g. the toner is not warm enough) or washed out by rapid fix, but it can fail too.
- It is possible to apply other bleach, e.g., potassium ferricyanide instead, but I have not tried it yet.
- For recipe 1, this ratio is mostly for a golden reflective sheen.
- For recipe 2, I mostly got tarnished or a combination of tarnished and golden reflective silver mirroring effect, but I also got an even blue-greenish reflective sheen; not sure why yet, but this could be related to the PH level.
- Mestre, J., Vergés, J., Udina, R. (2018). Silver Mirroring: Its Importance, Formation Process, and a New Elimination Procedure. Available at: https://www.ritaudina.com/en/2018/10/14/silver-mirroring-removal-from-historical-photographs/
- Baines, H., Bomback, E. (ed.). (1970). The Science of Photography. Fountain Press: London. pp.154-156