Sunday, January 18, 2009

Bulk chemicals vs. pre-packs

At some point one will ask themselves the question "Should I buy pre-packaged chemicals or buy them in bulk?" This is almost the same as deciding whether to do your shopping at the corner grocery store or at Costco.

The difference in price is great when you consider the chemistry needed for cyanotype.

I buy a lot of my supplies fro Bostick and Sullivan. They sell a pre-packaged cyanotype kit for $24.95. The kit comes dry, pre-measured in bottles. They state that the kit will allow you to make about 200 8" x 10" prints (about $0.12 per print). The kit is shipped dry, you simply add distilled water to the top of each bottle and shake and you're done.

What is very convenient and safe about this is that you never handle the dry chemical, there is no measuring and transfer, and little opportunity for the fine powder to go airborne. All that said, wear gloves and a mask when preparing and handling the kit. Once the solutions are made, the emulsion is mixed as needed in small amounts for coating paper by combining the two solutions in a 1:1 ratio. The shelf life of the solutions is two years.

What is cool about Bostick and Sullivan is they have instructions on line for several alternative processes, including cyanotype.

You can buy the chemicals for the cyanotype process in bulk from a place like Art Craft Chemicals. There are many formulas for mixing the sensitizer and the Prussian Blue precursor (ferric ammonium citrate and potassium ferricyanide). I am mixing 
  • Solution A: 20 grams of ferric ammonium citrate (green) into 100 milliliters of distilled water (the sensitizer)
  • Solution B: 8 grams of potassium ferricyanide into 100 milliliters of distilled water
I bought 1 pound of ferric ammonium citrate for $30.00, and 1 pound of potassium ferricyanide for $16.50. Normalizing the quantities (I need less potassium ferricyanide than I ordered) this is sufficient to make almost 10 times the amount of solution at only twice the cost of the Bostick and Sullivan kit, or very roughly 2 cents a sheet of 8" x 10" paper. And you can coat 2,500 sheets.

And herein lies the basic problem. How sure are you that you will like the process to do that much printing? Is blue your favorite color? The other problem is: to create the stock solutions you will need to purchase a small scale for weighing and some measuring cups (you're not going to use the measuring cups you use for cooking, just as you are not going to prepare the solutions anywhere near food). As you transfer the bulk chemicals and divide into smaller portions you have a much greater likelihood of airborne dust - more a hazard than the mixed solutions themselves.

A final problem is that these - and other chemicals for alternative processes - are hazardous materials. If you tire of a process you will have more chemicals to dispose of properly if you buy in bulk than if you buy the smaller kits. Christopher James's book has a good discussion on handling many of the chemicals for alternative processes.

Some things to consider as you explore different processes.

A final thought. It is well known that the sensitizing Solution A for cyanotypes is a perfect breeding ground for mold - I've been skimming it off in fascination. It does not seemingly harm the sensitizer (but can ruin a coating if you don't remove it from the solution). I never saw this with the Bostick and Sullivan kit - I think Kevin Sullivan is adding a preservative to Solution A to eliminate this problem.

I'm not a fan of mold.

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