Experiment: Applying Collotype Techniques to Bromoil

Gene Laughter:

Many of the old books on bromoil mention that workers often used soap in
the soak water. Glycerin is a basic ingredient of soap.

1. In collotype, the plate (matrix) is not soaked in water, but a formula is brayered onto the surface and the swelling lasts for approximately 100 impressions.

2. The formula varies, but the most prevalent seemed to be glycerin 2 parts, water 1 part ... plus some alcohol or ammonia. The alcohol acted as a wetting agent and the ammonia forced more swelling. Every studio's formula seemed to vary.

3. For this experiment I used only glycerin and water (two to one), brayering it on with a foam brayer for 30 minutes and then blotting the surface dry. Thirty minutes was derived from the book, Studio Collotypes.

4. Ink: I mixed up the ink that had been left on my tile over the weekend.

5. Inking: I brayered on the ink with a poly brayer, cleared with a wet brayer and then inked with a brush.

6. Total time spent in inking: Less than 10 minutes.

7. Matrix. A leftover 4 x 5 inch demo matrix from the recent workshop. Agfa MCC 118 paper. Size: 4 x 5 inches.

8. Conclusions:

A. I believe two parts of glycerin to one part of water is too much for bromoil. Will try half and half next time.

B. The glycerin/water mixture certainly made the matrix earier to accept the ink.

C. I need to wet a brayer for clearing as the ink blocked up the shadows.

D. I do not feel my ink was stiff enough. Collotype ink was stiffer than litho inks that we use. Next timme I will use stiffer inks and a hard rubber brayer, as was on the collotype presses. I will also add a bit of ammonia to the soak formula.

Overall: Inconclusive.

The image: The edges and outside extremeties of the left side and bottom
were purposely streaked and lightened with steel wool.

Studio Collotype

Gene Laughter:

I got the highly technical book, Studio Collotype by Kent Kirby and have
been busy studying it.

Collotype is essentially bromoil transfer using glass or aluminum as a substrate rather than paper and lots of heavy duty, fancy equipment. The
book has lots of interesting, highly technical stuff re inks and ink modification, effects of humity, etc. It's also interesting to note that it explains (and confirms) how potassium dichromate tanning causes links at the molecular level in the gelatin and those links form micro ridges (crinkles) that trap the ink, which is one of the main characteristics of the Collotype (and related processes) that make it possible. Perhaps Mortensen and Partington weren't so crazy after all. In fact, my guess is they talked to some collotype printers of the day. Printing high quality collotype illustrations for books was a decent size industry at one time.

A few other things learned from reading and studing the book, Studio

1. A special ink, called photogelatin ink was used for collotypes. **Photogelatin ink is an extremely dense, stiff ink, even more so than
lithographic roll-up ink. ** It's my guess that this is the ink that was used for bromoil in times past and labeled **Bromoil Ink**. Handsche Chemical Co., Chicago, still makes this ink to order.

2. Ink with less tack (short) is best used in the shadow areas and ink with more tack (long) is used in the highlights. I had never considered this. Of course! A revelation!!! The controls: Magnesium carbonate and bee's wax lessens tack and Canada Balsam increases tack.

3. Rubber base inks (Van Son) leaves less haze in the highlights and may
be used to thin photogelatin ink (collotype).

More to follow. Stay tuned!