The Mortensen Pigment Process

From Mortensen's extensive handwritten notes it is evident that he and George Dunham worked closely in the myriad experiments to develop the pigment process for which WM became famous. The following pages reveal, in Mortensen's own hand, some of the painstaking steps that were taken to find just the right set of ingredients and proportions for coating the paper. In the Appendix of Robert Balcomb's upcoming book, One Mortensen Student: My Experiences With the Master, William Mortensen, he writes:

In his Laguna Canyon studio Mortensen showed me how to paint an 11x14" sheet of Strathmore watercolor paper with a sub-coat of dissolved gelatin, dry it, then paint on a coat of watercolor pigments mixed with starch and sensitized with Ammonium Dichromate (or Bichromate) and set it in a dark area to dry (the sensitizer becomes light-sensitive when dry; the emulsion is very slow).

The coated paper was then covered with a paper negative of the same size made from a negative I had taken of George and sandwiched between two heavy sheets of glass, secured together with strong rubber bands. It was then placed outside in the hot July sun for an exposure of 2-1/2 hours, after which it was taken to the darkroom sink (with lights on) and washed. Areas where the sun had cooked the emulsion through the light areas of the negative had hardened and resisted washing off; areas which had received less or no light washed off, all in proportion to the amount of exposure.

The dried print was finally worked over with a Wollfe's carbon pencil to retouch it and add details such as the signature and monogram and to darken certain areas.

In the following notes, certain letters and words appear which may not be familiar. Here is a key to identifying some of them (others are a complete mystery):

Knox = Knox Gelatin Dist. = Distilled water Vano = Vano starch Wold = Wold Lamp Black W.N. = Winsor & Newton

"R" and "G" may refer to Red and Green color separations. "G°" and "M" probably refer to George Dunham and William Mortensen, respectively.

TEST EXAMPLES (click on thumbnail image to see full version):

	This is a sample of the many color-swatch pigment tests that Mortensen made.		An original drawing to test the pigment process.
	Another pigment test.		An exquisite photograph testing a sugar-and-formaldehyde subcoat.
	A test for Wold Sepia and Winsor & Newton Siennas.		Hot-press watercolor paper test using a fragment of "Pouring Milk."
	Formulas for making gelatin subcoats.		"Pouring Milk" testing matt and sheen subcoat surfaces.
	Vano starch formula. instructions for making the subcoat and pigments. Brush and roller techniques.		Odd George Dunham photo with notes on the back pertaining to the next pair of images.
	More subcoat notes. Also, WM practiced his signatures.		Two tests of "Pouring Milk."
	A test sheet in two halves, using different exposures.
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