Terry King gives an overview of gum bichromate printing, along with a step-by- step guide to the process. Fifteen years ago, I was in a similar. Gum bichromate process definition, a contact printing method in which the image is formed on a coating of sensitized gum containing a suitable colored pigment. In the late s, pictorialist photographers favored a diversity of photographic techniques, including the gum dichromate process. Sometimes superimposed.
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They are Bockingford lb and Fabriano 5 Not gsm. Keep away from food, children, pets, ;rocess. Other material Rabbit skin size, potassium metabisulphite from home made wine departments. Check your local art shop or graphic arts supplier. Film The gum emulsion is very slow and is only capable of accepting a density range of about 0. As with all chemicals, treat them with respect. Other tools A 5cc spoon from the pharmacy, long bladed plastic or steel palette knives and a white ceramic tea plate as your palette, map pins and drafting or magic tape, a contact printing frame or two pieces of 5mm plate glass.
Paper below gsm in weight will need stretching by taping it to a smooth surface around the edges of the paper and then soaking it so that as it dries, it shrinks and stretches. The light source will harden the dichromate in proportion to the densities of your negative. A negative or matrix is then laid over top the vum and exposed to a UV light source.
Gum Bichromate Process | NINIANE KELLEY PHOTOGRAPHY
You will need to preshrink your paper if you plan to do multiple print layers. It is good for your first experiments. Progression of print layers click to enlarge. A staining pigment will stain the whole of the image area.
William Henry Fox Talbot later found that colloids such as gelatin and gum arabic became insoluble in water after exposure to light. Before you begin, coat a small sheet of paper with emulsion and let dry. Some photographers prefer substituting the cyan emulsion in the CMYK separations with a cyanotype layer.
The negative is sandwiched between the prepared paper and a sheet of glass in registration with previous passes.
You may need to switch to a dry brush to help smooth the emulsion. For larger sizes, use graphic arts films. Several changes of water bath are necessary to clear the print. More information on casein printing can be found here.
Mix the dichromate crystals with the 80mL of warm water until dissolved.
When the print is completely dry and no more layers will be applied, a potassium metabisulfite clearing bath is used to remove excess dichromate trapped in the paper. My preference favors a potassium bichromaye.
As an example for a typical 8 x 10 print, combine 3 eyedroppers full of gum with 3 eyedroppers full of dichromate. I developed the film in bichrommate Dektol 1: A gelatin size coating prevents the unhardened dichromate from permeating the paper fibers. Insert into your contact printer or sandwich with your plate glass see step three in the Cyanotype process.
An introduction to the gum bichromate process
Liquid gum sold as an etching resist is too thin. Someone suggested to Demarchy that he should go back to the experiments of the s. Gum prints tend to be multi-layered images sometimes combined with other alternative process printing methods such as cyanotype and platinotype. Some are more complicated and achieve different aesthetic results. Gum Gum arabic comes from a tropical acacia tree. Indicate each step including how many coats, length of baths, and hardening agent for archival and personal purposes.
It can be as simple as taking a digital image and using photo manipulating software to invert and flip the shot to a negative making an inkjet print on paper or transparency film.
Those factors include the following:. Gum bichromate, or gum dichromate as it is also known, is a photographic printing process invented in the early days of photography when, inMungo Ponton discovered that dichromates are light sensitive. A heavy weight cotton watercolor or printmaking paper that can withstand repeated and extended soakings is best.
Gum bichromate – Wikipedia
Blackburn is a freelance photographer working in the Dallas, Texas area. I have been doing my first prints.
Gelatine is a very effective size and one that ggum gum printers continue to use today with excellent results. That procedure will help maintain the registration of your negative s as you progress from one print layer ggum the next. Start your sessions exposing a small test print of a step wedge or a negative with long tonal range for reference to help keep time and material waste to a minimum. Store finished solution in a light-tight bottle.