A Really Simple Cyanotype (Apologies to Mike Ware)

[gealto2]

A while back I experimented with Mike Wares "Simple Cyanotype" using concentrated ammonium hydroxide. I miked a solution somewhere between his low and medium density range formulas, going for a required density range about 2.0 to make it compatible with my VanDyke Brown printing negatives I've experimented with. For VanDykes, I use a formula from Sandy King that uses citric acid instead of tartaric, in fact that formula uses half as much citric acid as ferric ammonium citrate. This is also about the optimal DR for the new Ferroblen printing process for those following that.

As it turn out the Simple Cyanotype wasn't very simple. It was difficult to mix. I combined the FAC with the Potassium Ferricyanide, but it kept for ony a few weeks in the refrigerator. The sensitizer itself was not optimum for 2.0 density, but for closer to 1.5, and most of the blue dissolved out in the water like traditional cyanotype unlike the less soluble FAC I thought I had made. My ammonium hydroxide was supposed to be 28% but I had no way to confirm that.

Then I got the brite idea to mimic my Sandy King formula for VanDyke and use half as much citric acid as FAC with classic cyanotype. My thinking was that the VanDyke, which is a cyanotype developed with silver nitrate instead of potas. ferri. Since it's optimum for 2.0 dr, the classic cyanotype may be as well with the same amount. The simple cyanotype makes the sensitizer more or less acidic to control contrast. So I mixed a 20%-10%-10% sensitizer (fac-citricac-pferr) and coated some cheap watercolor paper. It much greener than normal, so I was worried it had gone bad with the paper. However it printed just fine, and was a fair match to my 2.0 density range negatives. Also, very little of the blue washed out, just as I expected with simple cyanotype. This allows much longer washing times than classic cyanotype without removing pigment. It also has better tonality than classic.

So this is a way to lower the contrast of classic cyanotypes and is much simpler. Ten percent is about the limit of how much citric acid can be added to a 20-10 (FAC-PF) due to solubilities, but less will give more contrast. It works the same way as Mike Ware's simple but has less of a range. I mix my sensitizer just enough for one sheet at a time. This also gives contrast control over a shorter range but still a useful one. Citric acid is more available, cheaper, and more stable than concentrated ammonia solutions.

Try it, you'll like it.

 

[koraks]

Simple Cyanotype wasn't very simple. It was difficult to mix. I combined the FAC with the Potassium Ferricyanide

I don't really follow this bit; I interpret this as follows: you're mixing Mike Ware's Simple Cyanotype, but in your case this involves ferric ammonium citrate and potassium ferricyanide. If I interpreted that correctly, IMO you're just making regular classic cyanotype, not Simple Cyanotype.

 

[gealto2]

I don't really follow this bit; I interpret this as follows: you're mixing Mike Ware's Simple Cyanotype, but in your case this involves ferric ammonium citrate and potassium ferricyanide. If I interpreted that correctly, IMO you're just making regular classic cyanotype, not Simple Cyanotype.

With Mike Ware's Simple Cyanotype, you are making ferric ammonium citrate by mixing ferric nitrate with citric acid, and then adding concentrated ammonnia solution in various amounts to adjust the contrast of the sensitizer solution by changing the Ph, then adding potas. ferricyanide to finish the sensitizer. Ware claims the nitrate ions left in that solution make it stable when refrigerated. This is very complicated way to make cyanotype sensitizer. Concentrated ammonia solution is only guaranteed to be in some range of values, so you need a way to measure the specific gravity of it. Very complicated. I assume this is why my attempt failed because I don't have an ammonia hydrometer or secific gravity attachment for my scales. The FAC forms as the solution is drying on your paper.

My simple solution which produces a very similar result, is to add 2% to 12% citric acid to a Classic Cyanotype sensitizer to control contrast in the same way, which is much, much, simpler. When FAC is dissolved in water it forms ferric, ammonium, and citrate ions. Making this more acidic by adding citric acid causes the ferric ammonium citrate to form on drying in the less soluble form as it does in Ware's Simple Cyanotype method. At least, that is my theory on why it works. Ware uses a fixed amount of ferric ion, fixed citrate ion, and variable amount of ammia ion. I use fixed ferric, variable citrate, and fixed ammonia, but it works similarly, I believe. The outcome is the same. The contrast is lower so I can print with higher density range negatives. The image qualtiy is better because the blue doesn't dissolve away.

Mike Ware is a great chemist and I am not. His formula is great for a commercial chemical manufacturing company to mass produce, but too complicated for home use. I know there is another way of doing Simple with alternate chemistry but others have failed with as well for unknown reasons. My experiment and finding this was by trial and error.

 

[fgorga]

Concentrated ammonia solution is only guaranteed to be in some range of values, so you need a way to measure the specific gravity of it. Very complicated. I assume this is why my attempt failed because I don't have an ammonia hydrometer or secific gravity attachment for my scales. The FAC forms as the solution is drying on your paper.

Measuring specific gravity (the modern term is 'density') is not complicated at all.

Four steps...

1) Determine the weight (in grams) of an appropriate container using a scale that measures to the the nearest mg (three decimal places). In this case I would used a closed container with a capacity of just over 100 mL.

2) Add a carefully measured 100.0 mL of the ammonia solution to the container and reweigh the combination.

3) Subtract the value determined in Step 1 from the value determined in Step 2 and divide by 100. This gives you the density in g/mL.

4) Use a table (such as this: https://airgasspecialtyproducts.com...queous_Ammonia_Solutions_at_20-4º_C_Table.pdf) to convert density to concentration (in % ammonia).

You will need to work carefully and accurately to get a 'good' value as, if you look at the table I have linked to above, the density varies over a fairly small range for ammonia solutions. However, you should get fairly close to the 'right' result with this method.