This method uses tannic acid to slow the action of the toner, sodium carbonate (washing soda).
Solution ONE , 1 g of tannic acid in 100ml of water
Solution TWO 1 g of sodium carbonate in 100 ml of water.
Immerse the developed cyanotype in solution ONE for a few seconds and then wash, retaining the tannic acid for future use. Immerse the cyanotype in solution TWO until the desired effect is achieved.
This should produce a brown cyanotype. Wash for five munutes.