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.

 

[nmp]

I think the impetus for making Simple cyanotype was to make a well characterized FAC from scratch, something that is lacking in FAC from commercial sources. (It is Simple compared to New cyanotype but not simple in absolute terms as it still involves some reaction checmistry.) The fact that it also allows one to control the contrast by changing the amount of ammonia in the formula is incidental as is the fact that the presence of nitrate ions make it more stable when ferricyanide is added. If contrast control is needed, one can also accomplish this by simply changing the ratio of FAC to K Ferri as well.

You can also replace ammonia with ammonium bicarbonate which will allow much better control with ratios than using ammonia when making Simple cyanotype. Alternatively, try Mike's cyanotype which he came up with later that uses triammonium citrate.

:Niranjan.

 

[gealto2]

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

Thanks for the information. My equipment does not have the accuracy needed. I would need to spend lots of bucks, as would other home users of cyanotype. Since my method of adding citric acid works, I have no need. This is why I'm sharing my method with others. It's trivially easy for any person that makes cyanotypes since it requires no new equipment or chemicals. I was also theorizing on why my attempt at Simple was a fail. It's just a guess.

 

[gealto2]

I think the impetus for making Simple cyanotype was to make a well characterized FAC from scratch, something that is lacking in FAC from commercial sources.

Yes, that's correct. Ware describes the reduced form as a less soluble form of Prussian Blue that doesn't wash out easily and dilute the highlights thus increasing the contrast there. I am taking the commercially sourced FAC and converting it from the highly soluble to the less soluble forms.

The fact that it also allows one to control the contrast by changing the amount of ammonia in the formula is incidental as is the fact that the presence of nitrate ions make it more stable when ferricyanide is added.

The improved tonality and contrast are the only reasons for this formula. It's interesting to chemists having a more regular form for the FAC crystals, but to photographers using it, the only reason would be better image quality. I believe Ware stated he thinks the nitrate may improve shelf life but isn't specific. He claims it has good shelf life in the mixed version when refrigerated. A couple of weeks is not very good in my thinking, but different strokes for different folks.

If contrast control is needed, one can also accomplish this by simply changing the ratio of FAC to K Ferri as well.

This doesn't work well. People have tried adding drops of potas dichromate for higher contrast, but who want higher? Everyone want lower, I believe.

You can also replace ammonia with ammonium bicarbonate which will allow much better control with ratios than using ammonia when making Simple cyanotype. Alternatively, try Mike's cyanotype which he came up with later that uses triammonium citrate.

:Niranjan.

These are the other ways of doing Simple I was referring to earlier. It has other problems I've heard, but haven't tried myself. Thanks for the fun discussion.