Gum Bichromate

The process of gum bichromate is a means in which to process images. It is a short tonal scale process. Gum Bichromate allows photographers to have freedom in the way their prints turn out. Gum bichromate requires many materials and equipment which can be confusing, but overall is said to be quite simple. The gum bichromate process began in the 19^th century. It was originally invented by Mungo Ponton in 1839 and later revised to its final form by William Henry Fox Talbot and Alphonse Poitevin. The process all together has twelve steps. Which goes along like this:

1. Negative Preparation - The negative needs to be enlarged in order to properly create a gum bichromate print.

2. Sizing Paper – The paper has to be the correct size before processing begins due to a water submersion processing which shrinks the paper about fifteen percent.

3. Preparing Sensitizer – The sensitizer is made up of a formula of Ammonium Dichromate, Water at 52 degrees Celsius and cool water.

4. Preparing Gum Arabic Solution – The solution remedy used includes, Mercuric chloride, Cool distilled water and powdered gum Arabic in liquid form.

5. Preparing Stock Pigment and Gum Solution – Add gum solution to total amount of stock pigment.

6. Preparing Paper for Printing – Place the enlarged negative produced in step one and lay it in the exact position sought after for the final print. Then, secure the negative with tape and create pinholes in the top two corners.

7. Preparing the Emulsion – The formula is made up of the prepared Ammonium Dichromate and the prepared pigment and gum.

8. Coating the Emulsion on Paper – During the emulsion process, you should be in a darkroom. First, secure the paper and then use brushes to coat the paper in emulsion.

9. Exposure – Place the negative and paper in contact frame and position it for exposure. The exposure could take anywhere from two to fifteen minutes.

10. Development – Following the exposure immediately immerse the exposed print in water face up for one minute and then transfer to another tray emulsion side down in a u-shape. Transfer the print back to tray one with clean water and continue this process for fifteen minutes to one hour.

11. Multiple Printing – After developing the print it is possible to repeat the steps of the process in order to create the complete range of tones possible.

12. Print Stabilization – Allow print to dry and then submerge in a five percent solution for five minutes. Then, give the print a running water rinse and hang to dry.

The gum bichromate process is still employed today by many photographers. One famous photographer who uses the gum bichromate process for all of their images is Massimo Attardi. Attardi is from Italy and resides in Rome. His gum bichromate prints have been processed on wood, paper, metal, glass, stone and plexiglass. Today, many of his exhibitions have been displayed in the Laboratory Museum of Contemporary Arts in Rome. 

This is an image created by Massimo Attardi. Gum bichromate on wood. Original link listed below.

http://www.co-mag.net/wp-content/uploads/2007/10/massimo_attardi_14.jpg