Wednesday, February 8, 2012

Barkanol ™

I was thinking about alternate developing agents and remembered that tea, the kind you drink, is leaves from a bush. Well, it must be possible to extract some developing agents from other plants and trees.

The tree bark contains a lot of chemical compounds, so maybe some of them will work as a developer?

Well, I dived into the basement and found some burning wood that still had some bark. I selected a species with dark strong smelling bark and carved off about 50g of the bark.

I brought it back to the kitchen and put it into a blender and grinded it into a fine powder.
This was transfered into a pan and boiled with about 500ml of water for little more than an hour.

I filtered the "tea" through a coffe filter and had about 300ml of the dark brown liquid.

Into this I mixed

30g sodium sulfite
30g sodium carbonate
3.5g salicylic acid
7.5g sodium askorbate.

This was diluted to 700ml.

A clip-test was blackened in a little more than 2 minutes, but the temperature was a bit  on the high side.
Correcting for the temperature I estimated a developing time of about 8.5 minutes.

The only testfilm I had for the moment was a PolyPan F exposed at 100 ISO.
That is one step push. Starting a developer test with a one step push development isn't what I prefer, but lacking another exposed film, this was going to be dipped into the developer.

Well, lets run the test and calculate the time for one step push development.
8.5 minutes x 1.4 is about 12 minutes.

Developing for 12 minutes worked out quite well. maybe a tiny bit overdeveloped. The contrast came out a bit on the high side so slightly less development would be perfect.
Grain is fine. About the same as with other fine grain developers.
The developer is ment to be used and reused again. I suppose it is possible to develop at least 12 films per liter developer before it is exhausted. Keeping qualities is unknown, but in short time I will test some chemical to increase lifetime of the developer.

PolyPan F @ 100 ISO.

PolyPan F @ 100 ISO.

Addtional information  March 20. 2012
Testing the Barkanol developer today showed no activity.
I even tried to develop a film with some test exposures. 100ISO B&W film for 12 minutes @ 22c gave almost blank film. Just some faint images can be seen.
I measured the pH and it hadn't changed. Well, something must have changed.
I suspected the developing agent from the bark was dead. This may be closely related to pyrogallol and it may be easily destroyed by oxidation.
To test this I added the equivalent of 0.015g/L of Dimezone-S, a phenidone variant.
This brought the activity back up to about the same as D76. This indicates that the sodium ascorbate is still intact, but the component from the bark is dead as suspected.

With this in mind, this is a developer that may be reused within a day or two, but despite adding several chemicals including Dequest 2010 to prevent destruction of the developing agents, it wasn't successful.
The chenicals has indeed protected the ascobate, but to no avail since the other component is destroyed.

To simplify this developer, the salicylic acid and the sulfite may be left out and the developer may be used as one-shot just as caffenol.

I have done some tests on caffenol using the same chemicals to increase the lifetime of the developer, but the same happens to the caffenol. It dies in a couple of weeks. Adding too much sulfite drops the activity of the developer.

Adding fresh coffe brings it back to life, so the ascorbic acid/sodium ascorbate is still there, so the coffe component dies after some time. Seemingly, neither ascorbic acid or sulfite will protect it from destruction, so mixed caffenol can't be tweaked to allow a reasonable long lifetime.


  1. For what I know as chemist what you may have in hands are catechols (similar to pyrocatechol with other substituents in the aromatic ring). These kind of compounds are very easily oxidized to the corresponding quinones thus loosing its "activity" as developers. In the case of caffenol, my guess is that the developing "agent" might be caffeic acid (another catechol type compound) with the same stability "problems".

    1. You have pointers to other, similar substances that we might find in our backyard?

  2. Well, I guess that almost every bush would have some of these kind of compounds, especially those producing berries, but I do not know of specific ones. In fact in virgin olive oil there is a considerable amount of hydroxytyrosol. I know that you are not going to use virgin olive oil as a photo developer (I hope, if so let me know!!), but if you have access to olive tree bark or leaves you should give them a try!

  3. Eucalyptus bark is high in caffeic acid too (for those in Oz or Hawaii)