Varnishing process
Step 15

“Iron mordanting”
Iron mordant is a method of dyeing wood black by reacting iron with tannins.
When the iron in the iron mordant solution penetrates the wood, it reacts with the tannins in the wood, gradually changing the color to a dark gray.
When using iron mordant, care must be taken to maintain high “fastness.”
So when dyeing, it is important to use a dark color.

The iron mordant process began yesterday.

Test coating with 5% aqueous iron mordant solution.
After a year and a half, it has become transparent.

After a few years, it was iron mordanted so that it would look like this cello.
Traces of iron mordant create a transparent navy blue image.
GIOVANNI GRANCINO ( 1637-1709 ) Cello, Milan 1690年頃

Joseph Naomi Yokota