Iron vitriol

Recipe for about 40 square meters of unplaned wood:

Dissolve 1 kg of ferric vitriol in 20 liters of hot water while stirring. Add 1 bag of water-soluble silver mordant.

Apply the solution to the wood with a brush. The iron vitriol water has no color of its own, but thanks to the silver stain, the surface immediately turns gray and this is visible, for example, if you have free spots. The iron vitriol’s own gray color only develops after a few months, while the stain disappears.

ATTENTION! Iron vitriol should not be applied to the wood until it is on the walls, otherwise there is a risk of applying too much solution and the color will be uneven.