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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Gum arabic A dichromate usually ammonium or potassium Pigment The emulsion is spread on a support, such as paper, and allowed to dry. Gum printing is traditionally a multi-layered printing process, but satisfactory results may be obtained from a single pass. The dichromates, formerly known as bichromates, are cumulative poisons that can be absorbed through the skin; the dust can eat away the mucous membranes, eg in the nose and lungs.
That procedure will help maintain the registration of your negative s as you progress from one print layer to the next.
Gum Bichromate Process
Several changes of water bath are necessary to clear the print. Download this article as a printable pdf. Blackburn gives us an introduction to the Gum bichromate process including a step-by-step to give anyone a good start. That was orocess health warning.
It is good for your first experiments. Successful gum printing can be achieved through a careful management of the many variable factors associated with the process.
As an arbitrary starting time for your very first print, set the timer for three minutes and adjust your next prints accordingly. Gelatine is a very effective size and one that many gum printers continue to use today with excellent results. I avoid problems of sizing and lack of lateral stability by using papers that are adequately sized and of adequate weight.
Photographic processes dating from the 19th century Alternative photographic processes. 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. The process is more forgiving as those two variables are effectively grasped.
Those experienced in the making of gum prints, however, might tend to add temperamental, tedious, and elusive to the descriptive repertoire. Make lots of sized paper at one time.
Both papers are PH neutral and archivally sound.
Gum bichromate – Wikipedia
If pigment stains paper after printing, repeat step 7 with remaining sized paper. Potassium Dichromate should be treated with utmost care.
Producing quality negatives ones that have adequate contrast and density and paper sizing are perhaps the most important variables to master, especially as you begin. Alternatives are blacklight fluorescent tubes or mercury vapour UV graphic art lamps which offer greater flexibility. Afterward, it is usually recommended that another coat be applied of the same color or perhaps another color over top of the first layer to help improve the tonal range and density of the print.
I have been doing my first prints. Fifteen years ago, I was in a similar state of mind to that of Robert Demarchy some ninety years before. In closing, here are four helpful disciplines you may wish to include in your printing routine: 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.
Brush as quickly and evenly as you can. Ammonium dichromate NH4Cr can be dissolved to the extent of one part in three in water. Before you begin, coat a small sheet of paper with emulsion and let dry.
Terry King gives an overview of gum bichromate printing, along with a step-by-step guide to the process. AKD-sized papers are my personal preference and have been for many years. You will probably see some orange solution wash away almost immediately. You will need to make contact prints and give more than one exposure if you wish to obtain a wide range of tones with good gradation.
Well that was fairly simple; remembering these principles should enable bichromxte to answer most of the problems that the process throws up. Gum bichromate or dichromate printing involves creating a working emulsion made of three components:. Should you choose a very strong UV source, a weaker solution may offer better control of your exposures.
Let your paper soak in very warm water for at least 10 minutes some papers may require more soaking time and proceess dry allowing the paper to shrink. Often just a minor adjustment of one or two knobs will make a big difference. Leave a comment Cancel reply Your email address will not be published.
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The following sources of materials are those that I have found give good and reliable service. Brushes The gum bichromate emulsion is essentially a modified watercolor.
Introduction to gum bichromate printing – National Science and Media Museum blog
And if that is the peak of your ambition, then fine. Label all paper with pencil after sizing. The beginner gum bichromate printer would do well to study the works of those early masters. Some are more complicated and achieve different aesthetic results. Hello Terry, Thank you for your inquiry. 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.