Making Cyanotype Prints
The Cyanotype, which is also known as ferroprussiate or blueprint was invented by Sir John Herschel in 1842, when he discovered that ferric (iron) salts could be reduced to a ferrous state by light and then combined with other salts to create a blue-and-white image. Not long after, Anna Atkins, one of the few women in photography during that century, published the first book with photographs instead of illustrations, "British Algae: Cyanotype Impressions"
Cyantype is a contact print process and you will need a negative the same size as the size of the print you want. A cyanotype with a blue image on a white background is obtained using a negative transparency. In order to obtain a pale white image on a blue background, a positive transparency must be used.
Cyanotypes are created with a simple solution of ferric ammonium citrate and potassium ferricyanide. If you don't want to find your own chemicals, Freestyle carries an excellent all-in-one kit for you.
The cyanotype emulsion is sensitive to ultraviolet light. Therefore either sunlight or another UV light source must be used for exposure. For consistent results, a UV light box is recommended. Freestyle offers an excellent, hand made version that is perfect for this application. Another option is to use a General Electric 275-300 watt sunlamp, but the light gets extremely hot, so keep your material at least 12-18 inches away from the bulb. It may be tempting to use a piece of glass to keep your negative down, but bear in mind that glass does not transmit UV light well.
Besides all the chemicals and a UV light source, Freestyle Advisory Board Member Jill Enfield recommends the following:
Apron, gloves, cheesecloth, hair dryer, clothesline, mask, clothespins, mixing rod, contact print frame, newspaper, cups and bows, pencils, distilled water, plastic spoons, drafting tape, plexiglas, drying screen/blotter book, scale, fan, tongs, glass and wax paper.
Following is a summary of the process containing important tips and reminders.
To learn how to really do it up in full, and make use of all these wonderful items, get a copy of Jill's book, Photo-Imaging: A complete Guide to Alternative Processes.
Characteristics and negative choice
The cyanotype process has a long exposure scale, so the best cyanotype prints are made when you use a negative with a wide density range. That means that if you have detail in your very bright highlights (Zone 10 or 11, for you zone system folks) you can reproduce it in cyanotype and still get great shadow detail. In general, if your negative will give a good print using grade 0 paper, it will give an excellent cyanotype print.
Almost any paper can be used. We suggest that you use a sized but unsensitized paper, which we offer here at Freestyle.
Want to use something other than paper? Fabric containing at least 50% cotton can be sensitized with cyanotype emulsion. Soak the fabric in the emulsion preparation and hang it up to dry in the dark. Stretch the material taut, place your negative and cover it with a piece of optically clear glass.
Be sure to handle all chemicals carefully. Use disposable rubber gloves, and mix and pour very carefully.
You will need at least three plastic or glass dark brown or black storage containers with plastic tops. Do not use metal. Two at 500ml and one at 100ml.
Distilled water is recommended over tap water.
Mix the light sensitive solution in subdued light. Once mixed, it will last only for 2-4 hours, so be ready to use it right away.
As with all printing, be sure to make a test strip before you make your print! On average a exposure time is about 10-20 minutes. Expose your print until the highlight values seem darker than you prefer. They will come back in the wash.
Wash your print for five minutes in running water. Be advised that if you have hard water, then a softening filter may be preferable. The iron salts in hard water can alter the appearance of the print. Be sure to wash for the full five minutes or you risk having your print fade.
Drying and Spotting
Dry your print in a dark room.
For spotting your print, use a Persian Blue watercolor.
Problem: The entire print turned blue and over exposed while drying.
Solution: It was not washed enough. To prevent this, rinse well, and dry print in darkened room.
Problem: My hands are blue!
Solution: Did you use rubber gloves? A good scrub with a strong soap might help. Otherwise, the stains will fade-away naturally taking a few days to a few weeks.