Re: Single coat gums
Hey Don and other gummists
While I don't have Mr Z's recipe I've found in the September 1921 issue of Camera Craft part two of an article called The Gum Process In Portraiture by Prof Daniel Cook with illustrations by Nancy Ford Cones. The recipe implies to me that it is a single coat process and I quite like the illustrations. Here's the recipe:
'The first step is to select a paper that has enough body to remain on the surface of the solutions. A paper that becomes saturated and sinks to the bottom of the tray is difficult very to handle, but the heavy grade of Whatman, and some imported papers, particularly the French charcoal, are very satisfactory. The next step is to prepare a solution of gum Arabic, 1 oz. to 3 ozs. of cold water, by placing in a muslin bag and suspending in a wide-mouth jar so the gum will be partly submerged. This solution will require about 30 hours to dissolve, and will be about the consistency of strained honey.
Next, a saturated solution of bichromate potassium is made, and is kept in a dark colored bottle, as this solution is sensitive to light. The paper is soaked in this solution until thoroughly limp, and then hung up to dry in a dark room. For the pigment, any dry color will do for a trial, black being easiest to work with. If moist water color is used, one should be sure that is has no oil, such as glycerine. Pigment is now gradually worked into the gum solution with a spatula until the proper amount of color is obtained. This will be the depth of the darkest shadows, a very interesting point.
A smooth board is next padded with several thicknesses of newspaper,a sheet of the sensitized paper is pinned on it, and with a bristle brush - about two inches is a good size - the color is quickly painted on the paper. One should try to cover the surface evenly at the first application, so that there will be no overlapping streaks, then one should immediately blend each way with a badger blender. When dry, the sheet is ready to print.
About the same exposure in bright sunlight is needed as required to print solio proof deep. In a tray with plenty of cold water, it is better to have it two or three inches deep, the exposed sheet is floated face down in the water, and as the bichromate dissolves out, the print is lifted carefully by one corner and allowed to drain for a few seconds so it will not stain. if the print has been properly timed, the outline should appear quite distinctly in about five or ten minutes. The paper should be left in the water until the image is fully developed. The time is usually from fifteen minutes to half an hour, although it is not absolutely necessary for the print to develop in such a short time. If it is over-exposed, the development can extend into hours and still make a good print, though of different quality. When dry, the print is more permanent than can be obtained by any other process.
The chief mistake with beginners is usually in coating the paper too heavily. In working with gum prints, one is more and more surprised at the small amount of pigment required to make a strong print. By practice one will be able to coat the paper to suit the negative. A very thin coating is required for a contrasty negative, while a flat, thin negative must have a heavier coating which will make a better balanced print."
----- Original Message ----- From: "Don Bryant" <firstname.lastname@example.org>
Sent: Saturday, May 19, 2007 12:46 AM
Subject: RE: Single coat gums