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Glimpses of Gumoil

Posted by on 11 Jul 2008 | Tagged as: Gumoil

Yes, we all know that one weekend’s workshop for learning the basics of both bromoil and gumoil printing is far too short, but nevertheless, the students were enthusiastic and started some great gumoil work to be continued later on their own.

Gumoil printing is an alternative photographic printing process, developed by Karl P. Koenig in 1990’s. Although it is not as historical as many other alternative techniques, it is clearly related to both gum printing (which uses gum arabic as binder to pigment) and bromoil (which forms the image with oily printing inks).

Every gumoil print is a unique piece. The process begins with coating paper with liquid gum arabic which is sensitized to light, continues with exposing the paper to UV-light in contact with a positive film, and ends with inking with oil color pigments after developing the image in water. After the inking stage the excess color is wiped off, and if multicolor image is desired, the print is treated shortly in bleaching bath. This will remove some of the hardened gum arabic and allow adding the next color.

Sequential bleaches and inkings can then be done until the print is finished, the whole process may take take several days or weeks. Adding more colors will produce more tones and sense of depth.

Digital positive films for exposing gumoil can be printed quite easily with an inkjet printer – the UV-blocking color doesn’t need to be extremely accurate, and one can experiment with different output options.

After the image has been converted to grayscale and adjusted to one’s liking, a Photoshop correction curve is applied. Here we used a curve that will lower the contrast and also lighten the shadows considerably.

We used Photoshop’s Hue/Saturation adjustment to colorize the image. After a few tests we chose red (360) as the “Hue” slider position. This image was then printed on transparency film with an inkjet printer.

After a successful exposure the image appears as a faint yellow-green print-out in inverted tones. The exposure has hardened gum arabic, and the unhardened parts can be washed away. After washing the print in water for 5 minutes or so, it can be sprayed with water to remove all soluble gum. The print is then dried, and it is ready to be inked with artists’ oil color.

The dried print is covered with oil color.

The image is totally covered with the paint, spread with a brush, sponge, paper towel, rag…
Inking can also be done with more than one color in turn, but the darkest tone (black) is usually the first and most intensive color of the palette.

Here the excess paint has been wiped off, and the original subject matter is revealed.

Gentle spray of water can help to remove the soluble gum at the water development stage.

Drying of the gum matrix may take a long time, but it can be hastened by an air blower.

Applying oil paint over the image.

More on gumoil printing

Gumoil photographic printing by Karl P. Koenig
Making The Gumoil Print (video)