Re: Cyanotype/Cuprotype

Jim Patterson,

Hi Niranjan,
The Se/S toner is my favorite.  It is Selenium powder dissolved in Sodium Sulfide solution.  It is listed in Anchel’s Darkroom Cookbook, 3rd Ed, p 296.  I dilute 1:20 for use.  Low odor.

Selenium powder dissolved in sodium sulfite works.  Selenium powder is very toxic by inhalation.  CAUTION.

2 % Sodium Sulfide solution works.
2% Liver of Sulfur (sodium polysulfide) works.
Both of these offgas Hydrogen Sulfide (toxic).

Thiourea sulfide toner does NOT work.
Kodak Rapid Selenium Toner does NOT work.

Some old developers (0.25% solution) bind to the Copper Ferrocyanide and air oxidize to a final color:
Amidol = purple brown
Rodinal = sepia
PPD + Catechol 1:2 = black.

Many of these are toxic.  Fume hood, outdoor ventilation, etc.  Don’t try these in the kitchen or bathroom.

On Jun 1, 2021, at 11:24 AM, Bruce McCaughey <steelbar@...> wrote:

Hi Jim
As I recall I  was trying to wash it out with long washes that did not work. I will need to try with citric acid. I did enjoy results so I will have have to revisit the process. 

On Jun 1, 2021, at 6:01 AM, Jim Patterson, <jimbobnola@...> wrote:

Hi All, 
I have several Cuprotypes several years old with no blue stains.
If any iron is left in the paper, a Cyanotype blue stain will result.  After developing in the thiocyanate/citric acid solution, wash well in at least 3 trays of citric acid water (1/2 tsp/liter) to remove all residual iron.  Then tone with the potassium Ferricyanide.  You can skip the Ferricyanide toner and use the Selenium/Sulfide toner at this point for a dark brown.

If printing a Cyanotype/Cuprotype combo, print the Cyanotype first to avoid changing the Cuprotype to a Cyanotype.

You can selectively change parts of a Cuprotype to a Cyanotype by using a small brush with Ferric Ammonium Sulfate solution.

On Jun 1, 2021, at 7:22 AM, Niranjan Patel via <nirpat89@...> wrote:

Hi, Bruce:

I am afraid a cuprotype is probably not in the cards for me imminently but when and if I try it, I will be sure to share here. 

Blue staining is probably something to do with not being able to clean out the residual irons, I am guessing but Jim would be the one to ask.


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