Gold toning for Van Dyke brown and Kallitype prints
A good formula to gold tone a Van Dyke print is the Clerc's formula.
With this recipe you can obtain a tone range that goes from dark red to neutral grey. In some case you could obtain both tones at the same time.
The formula is as follows:
Gold trichloride (so. 1%) 50ml
Thiourea (sol. 1%) 50ml
Tartaric acid 0,5gr
Sodium chloride 20gr
Distilled water 1000ml
Preparation of the solution:
Add the thiourea solution to the gold trichloride solution until the precipitate dissolves.
Dissolve the tartaric acid in 600ml of distilled water. Add the gold-thiourea solution to the tartaric acid solution and stir well. At the end add the sodium chloride, bring to 1000ml and shake until the solution will turn transparent. Store in a dark bottle. This preparation won't expire before 1 year time.
To tone a 8x10” print you need about 40-50ml of toner. To minimize the necessary amount we suggest you use a tray with a perfectly flat bottom. Dispose of the toner after you use it, it won't work a second time.
Toning must be done right after the development and a quick rinse; afterwords proceed with the fixer as usual, then wash throughly for at least 30-40 minutes.
Chemical products used in this procedure are to be considered toxic and non-suitable for human or animal consumption. As a user you must be aware of the risks and take care to protect the environment. Never dispose of chemical waste in a domestic sewage or with common garbage. For a correct disposal please see your local disposal laws.