with Tannic Acid

Come virare una cianotipia

One of the most interesting features of a Cyanotype print is the possibility of being toned in an infinite number of ways.
One of the most frequently asked questions that I am asked during a Workshop is just like toning a Cyanotype.
So let’s quickly see this process.

The Materials

First we need to decide how the final aspect of our toned Cyanotype will be.
To tone a Cyanotype we can use a multitude of “ingredients”. The most common are Tea or Coffee. Each type of Tea and Coffee (or any other element we decide to use) will introduce a different final shade. This is mainly due to the amount of Tannic Acid present in the infusion used as a virating agent.

Most of these agents introduce a color change with warm tones ranging from golden yellow to intense brown. But the interesting and characteristic part of this procedure is the relative impossibility of prior defining the final result.

In the example of this article the goal were to create a toned Cyanotype as close as possible to black and white. This result is usually obtained by using pure Tannic Acid and proceeding with a very long and complex color change.

The necessary “ingredients” are:

  • a Cyanotype print printed at least 24h before
  • a teaspoon of Sodium Carbonate (Soda Solvay)
  • two spoons of Tannic Acid
  • 3 liters of demineralized water
  • 3 trays

How to tone a cyanotype – the process

Place the three trays next to each other and pour one liter of demineralized water into each.
Starting from the left, dissolve a teaspoon of Sodium Carbonate in the first, leave simple demineralized water in the second and dissolve two tablespoons of tannic acid in the third on your right.
At this point the toning procedure can begin.

First, we proceed to moisten our Cyanotype in demineralized water. There is no definite time, the important thing is that the print returns to wet as before the final drying, after the washing at the end of the printing process.
Drain well the print and immerse it with the emulsion upwards in the Sodium Carbonate.
The print will begin to color magenta and lose definition in the highlights. There is no defined time for this phase and you will have to decide when to stop washing (also called “bleaching phase”). It usually doesn’t last more than 30 seconds.

After the 30 seconds of bleaching you will have to immerse the print again in the demieralized water to stop the chemical reaction with the Sodium Carbonate and, at the same time, for avoid to contaminate the Tannic Acid bath.
Leave the print for 30-60 seconds in water and then dip the print in the Tannic Acid.

The Tannic Acid bath can last several hours, depending on the colour you want to obtain.



From time to time a new washing and bleaching phase is carried out by passing the print first in the demineralized water and then in the Sodium Carbonate bath for another 30-60 seconds. The print is then washed again in demineralized water and then dipped again in Tannic Acid.
The print I present here required a process of about 3 hours with 4 Tannic Acid passages alternating with bleaching phases.

Cianotipia virtata con acido Tannico

During the more complex workshops, the toning phase with different agents (typically classic tea and coffee) is also addressed.
If you are curious, keep an eye on the next scheduled workshops by clicking below!

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