Posts Tagged ‘Cyanotype’
Last week I got interested in Cyanotype photographic printing and started investigating about the chemistry and the whole process of doing it. It’s real fun and cheap way of printing photographs. In short Cyanotype printing involves sensitizing Paper/wood/cloth/glass with some chemicals and expose it to UV radiation/Sun light with a negative film covering the print area.
There are hundreds of tutorial talking about the whole process, here I merely repeating the process again. In Cyanotype process two major components are the sensitizing chemical and the paper. Let’s talk about the steps in Cyanotype.
I followed the old Cyanotype process. The two chemicals I need for that is
Ammonium Ferric Citrate
Most of the tutorials of Cyanotype process talks about Ammonium Ferric Citrate (Green), I couldn’t find Green version instead I used the brown one.
These two chemicals comes as powder, so need to mix it to create A and B solution.
- Solution A: 100 ml water and 25g Ammonium Ferric Citrate mixed together.
- Solution B: 100 ml water and 10g Potassium Ferricyanide mixed together.
Note: some sources says, use distilled water, I used the normal filter water for mixing.
Both A and B should be kept in separate containers. This can be reused to create working solution. To create the working solution, take equal parts from two (A and B) solutions and then mix well.
Sensitizing the paper
Paper type is very important in Cyanotype process, I used different types of paper for this process. I got really good result from very cheap drawing paper sells at normal stationary shops, which cost around 8₹ for a large sheet and can cut 6 or more A4 sheets. I also tried with A4 paper which cost around 12₹ each and got a very dirty yellow look, which I didn’t like. I suggest start with cheap drawing paper.
Next we need to sensitize the paper with the working solution we created from the A and B solution. I used a normal paint brush and paint the solution to the paper. Make sure to use a moderate dark room. Keep the paper to dry in a dark place, I used my bookshelf to dry it completely. You can also use a hair dryer and can be used immediately, I don’t have a hair dryer instead I used a hot air gun in very mild temperature. The paper will turn yellow once it dried.
Printing or Exposing
I experimented with A4 size paper. To print photos, we need to create a negative of A4 size. To create the big negative I used a black and white photo and invert it in an image editing app. Then adjust the contrast to get a desired look for the negative. This negative should print on a transparent sheet, I bought couple of OHP sheet and print the negative using my laser printer.
Next we need to expose the sensitized paper with UV rays. I used an A4 size plywood and transparent plexi glass to keep the paper and negative in position. Here is good video showing the whole process.
Sun light is the best resource for UV rays. But I live in an apartment and I don’t get enough sunlight in my balcony. So I used a light source created for my Aeroponic system. My Light source is an array of 3W red and blue LEDs, which I sourced from Aliexpress and assembled by me and my father. Also this artificial UV source helped me to experiment at night as well. Below is my UV light source, it’s not very fancy, a DIY system. Important part is, it’s shock proof :).
In normal sun light, we need to expose the paper for about 8-10mins, in my light source I need to expose for around 50mins. I experimented with different exposure time and came to 50mins as ideal.
Developing the paper is an easy process, just dip the exposed paper in water for 3 to 4 mins. My tap water is bit Alkaline, Cyanotype works well in Acidic water, so I put couple of drops of Phosphoric acid to water to make it acidic and wash for a minute then wash it in normal tap water for about 3 mins. The timing can only determined by trial and error, when you see the blue color is fading take the paper out and keep it for drying.
1. Dirty yellow stained print, this caused by the paper type. This A4 sheet is around 12₹, but gives me a very bad output.
2. An over exposed print, highlight become mild blue. Under UV Light for around 2hrs
3. Reasonable good print, exposed for around 50mins.
All the above photos are scanned using a normal scanner not from a good photo scanner. Later I will post some photos from my photo scanner. The actual image looks a bit more bluish.
I need to spend some time experimenting the bleaching and tanning process. The whole process is real fun, need to experiment with different photos as well.