(Source : Basic Photography - Michael Langford)
Hot water 750 ml
Sod. Thiosulphate cryst 150 g
Pot. alum crystals (added slowly) 25 g
Water to 1 litre
Then either add to this solution :
Silver Nitrate cryst 0.14 g
Just sufficient drops of strong ammonia sol. to dissolve the milky precipitate.
- OR -
Ripen the toner using several waste prints before use.
Prints tone in approx. 5 mins. @ 50ºC. Wash well and swab to remove any scum.