Gum Bichromates – Failure & Progress

For some weeks now I have been struggling with gumbichromate and it has given me some gum(sad) time. Here, sharing with you some experiences and lessons learnt.

In the process of gum bichromate we uses,

  1. Potassium or ammonium bichromate
  2. Gum Arabic or Gum acacia powder.
  3. Water color paste.

Though this looks very simple, so as I thought but there are different variables which makes this process stubborn. I started off this process as recommended by http://www.alternativephotography.com  but the result was far from satisfactory. While I started off with 30% solution of gum acacia to 10% solution of potassium bichromate. Initially I got some faded images which when exposed in sun 30 to 45 min.

Till this time I couldn’t figure out the problem.

After this I tried this process on various kinds of papers and instead of distilled water i was using normal tap water. The time it was taking for printing was very long  like one and half hours under sunlight and the impression was faint. Here while washing , I was using the brush rigorously, hence you can see some scratch on some prints.

In the next phase the distilled water was used and UV light was fixed. Meanwhile  Shreyasi  Kar visited us. She made a good print using 1:2 ratio of potassium dichromate to gum. Her exposure time was two min in sun. Now I tried repeating the process under UV light.

2 min exposed under UV light

2 min UV exposure with increased color pigment.

4 min in UV light

8 min under UV light

12 min exposure under UV light

One important lesson I got here is distilled water and a good water color paper makes a huge difference. Third phase will be in the next blog.

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2 Responses to Gum Bichromates – Failure & Progress

  1. Arpan Mukherjee says:

    Dear Tanima

    there is no need to expose the matter for so long. the 30% gum and 10% Ammonium Dicromate with sun is a very strong combination. I’ll suggest you to go for UV exposing table instead of sun. even you can expose it under normal tube light banks. the distance between the matter and the light determine the exposing time ( with many other parameters). in my case i use 6 UV tube light bank and the distance between the matter and the light is 6″. i use 30% gum and 10% A.D in 1:1 ratio. the maximum expos i give is 1min45 sec. and i got excellent result both in color and B&W prints.
    Dont develop with brush go for automatic development, dip the print upside down in a tray of water (normal) for 30 m change the water you will get the print.
    Another important thing is are you sizing the paper with gelatin ? It gives the white of the print.

    • tanima das says:

      Hi Arpan
      Thanks a lot for the information .. I tried with exposing with uv light.. i will put that on in the next phase of the blog. I am using Potassium dichromate instead of Ammonium ..i have’n tried sized my paper with gelatin. i will try but. I will put on my further findings, do follow and your suggestion are greatly welcomed. thank you.

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