Quote Originally Posted by Gerald C Koch View Post
There is also a thiourea toner which uses sodium carbonate instead of sodium hydroxide.

Thiourea 2.0 g
Sodium carbonate monohydrate 100 g
Water to make 1 l
The great thing about this recipe is that you can fine tune pH with Bicarbonate and achieve unbelievable control over the tone you get, from dark brown all the way to very light yellow.