GUM BICHROMATE PROCESS PDF
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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A UV light source see Dr. The variables become more manageable while the image quality is virtually identical. I, for my part, went to a talk by a gentleman from Maidenhead called Steinbock. 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.
Label all paper with pencil after sizing. It can be as simple as taking procesz 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. Light You need near ultra violet light x m available free from the sun but inconsistent. Check for adequate density and contrast.
Both papers are PH neutral and archivally sound.
It is an essential key to quality gum printing. Before you begin, coat a small sheet of paper with emulsion and let dry.
Check your local art shop or graphic arts supplier. Increase your time until you begin to see pleasing images which capture the details of your negatives.
Consult a paper supplier or the manufacturer for current information. The dichromate molecule can be excited by light at the right wavelength to throw one of its oxygen atoms which fills in the gaps between the spurs on the gum molecule chain. Just do a search on this site to find it. I cannot any longer aford large film negs. The ammonium compound is three times bichromatw nasty and three times as fast. Gum bichromate is a 19th-century photographic printing process based on the light sensitivity of dichromates.
In my opinion, you have two basic choices. Part B is a saturated solution of dichromate salt. As an arbitrary starting time for your very first print, set the timer for three minutes and adjust your next prints accordingly. Each layer of pigment is individually coated, registered, exposed and washed. Potassium Dichromate should be treated with utmost care. Hello Terry, Thank you for your inquiry.
Film The gum bifhromate is very slow and is only capable of accepting a density range of about 0. Put in terms that I can understand, the gum molecule is a flexible chain of hydrogen and carbon atoms with oxygen side spurs. Papers that are gelatine sized sometimes need additional size applied to the surface followed by an application of a weak formaldehyde or glyoxal solution hardener to help maintain paper quality throughout multiple print layers and many water baths.
One would think gum printing has, at last, come of age. I have lrocess doing my first prints. It is capable of rendering painterly images from photographic negatives.
Introduction to gum bichromate printing
You might try a mixture of Prussian Blue with Burnt Sienna as an alternative to single black pigments. Start with proccess good negative: Make a test exposure on the small sheet using a Stouffer scale to determine correct exposure time for your light source.
And if that is the peak of your ambition, then fine. The print emulsion consists of a saturated solution of potassium dichromate, gum arabic, and a coloring agent, in this case, watercolor pigment.
But the technique of this black and white print gave it a power, a hyper-reality that seemed to outshine so many of the silver gelatin prints I had seen. There are probably no two gum printers who approach their work in precisely the same manner.
procwss There are many other ways of making a gum print. Alternatives are blacklight fluorescent tubes or mercury vapour UV graphic art lamps which offer greater flexibility. Gouache was added as the final touch.
Gum Bichromate Process | NINIANE KELLEY PHOTOGRAPHY
Artists choosing to use the sun for their UV source can expect to see a greater degree of variation from print to print than those using a more consistent light source. Why let your paper soak unnecessarily in dichromate that otherwise can easily be removed by a brief initial rinse? Paper formulations can change, often without notice, greatly affecting the quality of your work. That procedure will help maintain the registration of your negative s as you progress from one print layer to the next.