Cyanotype FAQ
Short answers about making cyanotype prints and digital negatives, with the sources quoted under each.
What is a cyanotype?
A photographic printing process that gives Prussian blue monochrome prints, made by coating paper with iron salts and exposing it to sunlight or UV. The Getty Museum credits Sir John Herschel with inventing it; Jacquard dates the discovery to 1842. History.
“Cyanotype is an antique photographic printing process distinctive for producing Prussian blue monochromatic prints.” [Jacquard, Cyanotype FAQs]
“Sir John Herschel (1792-1871), a confidant of William Henry Fox Talbot and scientific colleague of Atkins’s father, John George Children (1777-1852), had invented the process.” [Getty Museum, Anna Atkins, British Algae]
“Discovered in 1842 and distinctive for producing rich, Prussian blue monochromatic prints, Cyanotype was popular well into the 20th century as an inexpensive method for reproducing photographs, documents, maps and plans (hence the enduring architectural term “blueprint”) and famously, for making impressions of biological specimens in the field (“photograms”).” [Jacquard, Cyanotype Chemistry]
How do you make a cyanotype?
Mix the sensitizer, coat the paper and dry it in the dark, lay an object or a negative on it, expose it to sunlight or UV, then rinse it until the water runs clear and dry it. The steps are quoted from Jacquard's instructions. How to make a cyanotype.
What can you print a cyanotype on?
Jacquard says any natural surface can be treated with the sensitizer, and that polyester generally cannot be used.
“Yes, any natural surface can be treated with the cyanotype sensitizer, including silk, cotton, wool, hemp, linen, canvas, paper, leather and wood.” [Jacquard, Cyanotype FAQs]
“As polyester is not a natural fiber, it generally cannot be used for cyanotype.” [Jacquard, Cyanotype FAQs]
How do you make a digital negative for cyanotype?
Make a black and white, inverted version of your photo, print it on transparency film at 100%, and use it on the coated paper where you would use an object. The free tool here previews it on screen from a photo: it crops to the paper, turns the photo black and white, and inverts and mirrors it. Full-size print negatives at 4 × 5, 5 × 7 and 8 × 10 are made in the Cyanotype app; you can also do the same steps by hand in any photo editor. The digital negative preview.
“Use a digitally-printed photographic negative (an inverted black and white photo inkjet-printed onto a transparency*) instead of an object to create full-resolution photographs on paper or fabric.” [Jacquard, Cyanotype Chemistry]
Why is the negative mirrored?
The Cyanotype app's negative sheet tells you to lay the printed side against the coated paper, and the app mirrors the negative so that the print then reads the right way round. The preview here does the same. The digital negative preview.
Does the digital negative include a calibration curve?
No. Neither the preview nor the app applies one; the app's sheet says to print on transparency film at 100% and adjust exposure to your chemistry.
How long should I expose a cyanotype?
Jacquard's kit says 10-20 minutes in sunlight or UV, depending on conditions. The Getty Museum, describing the process, says five to fifteen minutes in the sun. Neither source gives a UV-lamp time, so this site does not either. Exposure time.
“Coat the included Hahnemühle Platinum Rag Fine Art Paper with the sensitizer and, once dry, create prints by exposing to sunlight or UV (10-20 minutes, depending on conditions), using the included glass printing frame and objects or a film negative to create an image.” [Jacquard, Cyanotype Kit]
“The entire package is placed out in the sun for five to fifteen minutes.” [Getty Museum, Anna Atkins, British Algae]
Does the app tell me the exposure time?
No. The Cyanotype app makes the print preview and the negative; the exposure is yours to find for your chemistry and light.
Is a cyanotype permanent?
Jacquard calls cyanotype prints archival, with cautions about phosphates and alkaline environments and about over-washing. The Getty Museum calls it one of the most permanent processes.
“Yes, cyanotype prints are archival. However, yellowing may occur if prints are exposed to phosphates or alkaline environments” [Jacquard, Cyanotype FAQs]
“Over-washing may also cause the print to fade.” [Jacquard, Cyanotype FAQs]
“It turned out to be one of the most permanent processes as well.” [Getty Museum, Anna Atkins, British Algae]
Why is my cyanotype blurry, pale or yellow?
Jacquard's troubleshooting sheet explains each: a negative that is not flush on the paper, a print not exposed long enough, or exposure to phosphates, soap or dirty objects. Troubleshooting.
Can you tone a cyanotype with tea?
Yes. Jacquard describes toning as two steps, a bleach step and a toning step that needs tannins, and says teas that contain tannins, such as black tea and green tea, work. Toning with tea.
“Toning a cyanotype print generally involves two basic steps: a bleach step, and a toning step.” [Jacquard, Toning Cyanotype Prints]
“Make sure to use teas with tannins in them, like black tea or green tea. White tea, red tea and most herbal teas don’t contain enough tannins to effectively tone a print.” [Jacquard, Toning Cyanotype Prints]
Is cyanotype safe?
Jacquard says care should always be taken to avoid ingestion, inhalation and contact with skin. The Photographers' Formulary data sheet for ferric ammonium citrate rates it slightly hazardous. Read the safety data sheet of what you buy; this site gives no handling advice of its own.
“Cyanotype is non-toxic and does not present any significant health risk or danger. That said, care should always be taken to avoid ingestion, inhalation and contact with skin when handling the cyanotype chemicals and fabrics.” [Jacquard, Cyanotype FAQs]
“Slightly hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation.” [Photographers' Formulary SDS, ferric ammonium citrate, green]
“Information on the human health effects from exposure to this substance is limited.” [Photographers' Formulary SDS, potassium ferricyanide]
Can I see a photo as a cyanotype before I print it?
Yes. The free cyanotype preview on the Cyanotype app page turns a photo into a Prussian-blue print in your browser, and the iPhone and iPad app does it in seven looks. Cyanotype preview and app.
Is my photo uploaded?
No. The digital negative tool and the preview run in your browser, and the app makes no network connections.
On your phone: Cyanotype
For iPhone and iPad.
The app shows your photo as a cyanotype print first, in seven looks, with print sizes and matte borders, so you can see the blue before you coat anything. Then it exports the digital negative at full resolution: black and white, inverted and mirrored, and for 4 × 5, 5 × 7 and 8 × 10 paper at the resolution that prints at the paper’s size. It all happens on the device. There is no account, and the app makes no network connections.
How this was checked
Statements about the process, its chemicals, safety and history are quoted word for word from the maker’s instructions (Jacquard), the Getty Museum and the Photographers’ Formulary safety data sheets, and linked where they appear (checked ). Where we could not fetch a source for a fact, we left the fact out, so this section gives no concentrations or amounts of chemicals: use the instructions and safety data sheet that come with what you buy. The digital negative tool is compared by an automated test with the Cyanotype app’s own code. If something here is wrong, tell us at a@noshu.net.