Tuesday, March 30, 2010

Sun Printing, for when the sun Comes out (Cyanotype)

A Brief History of Cyanotypes
Cyanotyping is a photographic printing process that gives a cyan(blue) print. It is one of the cheapest, simplest, and oldest photographic processes dating back to the 1840s. Cyanotypes are made by coating a piece of paper with a 1:1 mixture of Potassium Ferricyanide and Ammonium Iron(III) citrate (C.F.) Cyanotypes were later used by engineers because they were simple and cheap to produce, this is where we get the term "Blue Print" from.

Making the Mixture
The Mixture is a 1:1 ratio (10ml:10ml, 1oz:1oz, etc) of Potassium Ferricyanide and Ammonium Iron(III) citrate that applied to an absorbent surface and allowed to dry in the dark. The 2 mains ways to get your cyanotyping chemicals are to order them in liquid form. You get 2 bottles one is "Solution A" and the other, "Solution B" you can get around 1/2 liter of each and they're sold together for around $20.00 from B&H. (http://www.bhphotovideo.com/c/product/313645-REG/Photographers_Formulary_07_0091_Liquid_Cyanotype_Printing_Kit.html) That's how I get my chemicals. For those who want to be a bit cheaper, need more than the liter of solution that you get from Photographers' Formulary or are just a little more ambitious than most, you can order the chemicals in powder form, and put them in solution yourself etc, this will require a bit further reading and some experimentation, but it'll be cheaper and possibly more fun/versatile.

Once you have your chemicals in solution (whether you ordered them from photographers forumlary or you ordered in bulk) you now make a 1:1 mixture of the chemicals. Typically I do a 1/2 a cap of each. Stir this together (using the brush is fine) and now apply this to your medium. Typically I use watercolor paper, and apply it with a cheap foam brush, but you could use any number of surfaces/brushes (C.F.)After the mixture is painted on (and you want to do this away from UV light as we are dealing with a UV sensitive chemical) you want to store it in the dark until it dries.

Preparing the Print
This entire process will vary based on what you're printing, here's a basic guide, but be creative! Typically I try to print things I find outside, such as leaves and branches, but I've also tried other stuff--paper clips are an alternative. You're not limited to objects of course, you can make prints of (dense) negatives. Once you've chosen your object/negative/whatever, place it on the paper, put glass over it to keep it flat on the paper (the flatter the sharper) *Don't use glass with a UV coat! and clamp it together (between a board and glass or something of the such.)

Exposing the Print
This is the part where experimentation is really required. The amount of sunlight required to expose the print varies from region/time of day/time of year, etc. Most of my stuff I did in the winter in the north, not a lot of sun, I left prints out for a 1/2 hour or so. Its easy to tell when they're ready as they start to change colors a little bit and if you move what you were exposing there should be an outline.

Basically what happens is the UV light from the sun reacts with the mixture and causes it to become fixed and bond with the paper, where as what is hidden under the object/negative isn't exposed and when the print is rinsed this bit washes away!

Developing the Print
Once you've made the paper, let it dry, picked something to make a print of (the hardest part) and left it out in the sun for a suitable amount of time you now need to wash out the not exposed bits, and finish "fixing" the rest. This is accomplished by rinsing the print under some water! I usually do this with a big dish tub I got at the dollar store. Just put the print in, and you'll start to see the covered bits washed away and the greenish brown exposed parts turn blue. Agitate this solution for a few minutes/until it stops changing a lot. Now take it out of the water and let it drip off a bit, transfer into a tub with a bit of water (at least 4cm or so) and a cap or 2 of Hydrogen peroxide (h2o2) this acts as an oxidizer and gives the print its nice deep "Prussian Blue" color. Let it soak for a minute or two, agitate it around, take it out, shake it off and hang it up on your DIY/make-shift print drying line!

Sit back, and enjoy the time lapse of me making cyanotype paper, notice the proper lab technique of eye-balling my 1:1 ratio, and the fact that I'm wearing a lab coat.. I use any excuse to put it on. I apologize if you're in German, Apparently Sony doesn't want you to hear the song in the video. It's "Sunshine on my Shoulders" By John Denver--I saw the name as fitting the concept of sunprints here.

And Here's the video on how to expose/develop your cyanotypes! Thanks for reading, and stay tuned next week for some crazy cyanotype ideas!

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