Test 3 Gum Bichromate - Final Integrated Assignmet

Now that I had made a decision on the theme of this final photographic project it was a case of what creative approach to take. Through university I have been exposed to the alternative photography processes. This is something that really intrigues me with the more manual approach to creating imagery. One such process is Gum Bichromate. Invented by Mungo Ponton 1839 when he established the light sensitive properties of dichromates. A little later, Fox Talbot, whilst experimenting with this chemical,l found mixing it with Gum Aribic or gelatine, exposing to sun part of the image became insoluble after washing in water. Both Alphonse Poitevin and John Pouncy further develop this technique in the 1850, by combining carbon pigment and then colour pigment to the chemical, respectively. The distinct appearance of this process was particularly of interest to a new photographic movement - the Pictorialists. This group sought to distance themselves from the growing amateur photographers of the time (1880's). They looked to create imagery rather than just record. The Gum process with its dreamy soft painted look was ideal for this new group of photographers, the major exponents of this process were photographer such as Edward Steichen and Robert Demachy.


The Gum process require a negative that can be contact printed. For this I will be using 5 x 4 negs. First thing to say is I have had no training in the Gum process and when researching the process there are many statements stating that this is a process that can take time to master. Oh well, I'll give it a go. The starting point was to research the process, for this I used Christopher James book, "The Book of Alternative Photographic Processes and Sarah Van Keuren "A Non Silver Manual". The first item that both these authors write about is the hazardous  chemicals that are used in the process. They are not trying to frighten here - far from it. They want to instill caution that one particular chemical 'Potassium Dichromate' if not used properly has some serious side effects. Potassium Dichromate is poisonous and highly allergenic. Safety equipment must be worn which included dust mask, safety glasses, latex gloves and an apron. The below in an extract from Christopher James book on the safety of dichromates.

NOTE: Be cautious in how you handle ammonium or potassium dichromate: It is dangerous and poisonous and highly allergenic. Never put bare skin in contact with any dichromate solution. This chemical can cause lesions on your tender flesh through contact and can damage your lungs by breathing it in its dry state. Be very careful with storage and never leave the chemistry unlabeled or where children can get their hands on it. 

With the above warning at the forefront of my mind I proceed with caution.




The Gum Process comes in two parts: the first is preparation of the paper, the second is the actual printing of the gum process.


Paper Preparation:

You can print on many different substrates and papers using the gum process, but using the experts recommendation I chose to print on Fabriano Artistico water colour paper. The first thing to do is pre shrink the paper, this is done by soaking pre ripped paper in a tray of hot water for 10 minutes. Hang to dry.

The next stage is to size the paper. This allows the colour pigment to attach itself to the substrate. Take one level tablespoon of knox gelatin and sprinkle it on the surface of a glass jug of cold water 250ml. Allow the gelatin to soak up the water - 10 minutes. Heat a double boiler to a temperature to 54 c. Maintain the heat and ensure the gelatin is fully submersed in the water.

Tape the now dried pre shrunk page to a board. When the gelatin is ready paint onto the paper with a sponge brush. Vertical strokes followed by horizontal. Allow to dry before applying a second coat. However, the gelatin must remain at this temperature or it will solidify. The use of a hairdryer speeds up the process at this stage.  Once two coats have been applied leave to dry.

                                 Getting ready for gum printing.




Printing Process




The first part of the gum process is to prepare all the chemicals. The recommendation is to use a 10% potassium dichromate saturated solution. To do this mix 10 gr of potassium dichromate with 100ml of distilled water. Pour into a dark medicine bottle and label correctly.


Now we're ready to print:


Next make a sensitise solution, pour 6ml of gum arabic into a plastic cup, next take your chosen water colour paint or gouache paint and mix between a quarter inch to an inch. Mix thoroughly together

Add 6ml of the pre pared dichromate solution and mix well.

Mark out the image area on the water colour paper to indicated where to paint up to. Paint quickly and lightly in even vertical strokes then horizontally. Work the paint into the paper until it just becomes taken. Allow to dry.

Put the sensitised paper in a contact frame, put a chosen negative emulsion side down onto the paper. Take outside into sun light for exposure. The recommendation for exposure are 2 to 10 in full sun, but this will depend of time of year and cloud cover. The sensitised solution will only react to UV light. This is all a bit trial and error.  You can use a test strip but with changeable condition it can be a bit superfluous. An artificial light can be used and is probably the best way to control exposure.

The next stage is to wash the print, I set up 3 trays of cold water for this purpose. Once the paper is exposed take out of the contact frame and remove the negative. Put the paper exposure into the first tray and rock gently removing the orange dichromate solution. This is roughly 10 minuets. Remove and put in the next tray rock the tray to remove any paint from the image, you can pour water from a jug from a height to aid with this. The third  tray is used if fresh water is required.

Once the image is washed to your liking remove and dry.




Conclusion


As they say the gum bichromate process is very addictive and its one that I will pursue to become competent in. I really like the paint effect that you are able to active. This is just the look I am after for this final project.