Gum Bichromate Printing Reversal Demonstration

Here are two early samples which demonstrate the problem of a gum bichromate print where the resulting print has reversed out to a negative. The original negative is 4x5 shot on Tri-X film. Ignore the dust marks etc. on this first print as it was taken from a poor quality contact sheet, however, it will serve as a reference point for what the final product should look like.

Now, here is the same negative printed on gum bichromate -- as you can see, the level of detail is quite good. The gum print was made using an emulsion mixed as follows:

• 2.5 ml gum arabic solution


• 2.5 ml potassium bichromate solution


• 0.5 gm Daniel Smith Lamp Black watercolour pigment

The problem is that Lamp Black is a very heavy pigment and 0.5 gm is way too much for this amount of emulsion. You can see that the image has reversed itself to negative. The emulsion was coated on Lanaquarelle Medium Watercolour paper (140 lb.) and the print was exposed for 20 minutes under a #2 blue photoflood lamp in a reflector about 25" away from the print.

Partial Success?
Here's what happened after I switched to Daniel Smith Burnt Umber using similar amounts of gum and bichromate as before. It still reverses!! The amount of pigment was approximately 0.1 gm. although it is difficult to measure such a small amount even with my triple beam balance. I should also note that the gum arabic solution used for these first three prints was made up from gum powder. I'm not sure about the percentage solution, but it is quite thick.

At this point in my testing, I switched to the premixed gum solution sold by Photographer's Formulary. Finally, I got success with the same formula as before, however, the contrast level and exposure are not acceptable.

Gum Bichromate Testing #1

Printing the Adobe Olé black and white test neg today. Pigment load 0.2 grams Payne's Grey in 2.5 ml gum arabic and 2.5 ml potassium bichromate. The mix is enough to make two 7x9 images on Arches Aquarelle paper. Mixing the emulsion to ensure consistency because I think past problems have arisen because of not taking enough care. Poor mixing leads to splotchy emulsion. Coating evenly is a major technique to learn.

Exposures: 5 minutes and 4 minutes.

Also tried a new approach to development using two water baths. The first water bath for about 10 minutes and the second for about five minutes seems to fully develop the image. Used the same water for both prints.

Analogue: Holga Images @ Wired.com

After Flight
Submitted by Vitala Tauz









Analogue lives! Wired.com recently sponsored a competition for photographs made with Holga cameras and film. I've got a Holga and it's fun to play with. Here's a fantastic sampling of what people are still doing with film on the Wired web site.

Top 10 Wired Holga Photos

WWAD?

What Would Ansel Do? (stealing a question from the Evangelists). I've often wondered how Ansel Adams would be responding to Photoshop, megapixels and dpi. Would he be using Photoshop to manipulate the Hurter and Driffield curve he helped to define in practical terms? In his day, he had to adjust the slope and shape of the curve through careful and exhaustive testing of many film, developer and development time combinations. This was the only way to adjust image contrast and hold the Zone III shadows and the Zone VI highlights within the printable range of the paper.



Today, a few mouse clicks offer many times more flexibility with the results immediately viewable on the screen in front of you. Colour balance problems? Split your RGB image into its channels and adjust the curve of each to get just the right balance. Want to create a negative to print on platinum? Download one of the many available ready-made curves designed especially for platinum. It's almost too easy.

Ansel Adams was a keen experimenter and early adopter of new technology. If the result was a print which captured his artistic intention more precisely, he used it. Would he use Photoshop?

Digital Vs. Analogue Photography

One of the things I'm interested in exploring is the digital vs. analogue debate among photographers. For many people this is a no-brainer: digital is here, so get over it. But, like most things in life, it's not that simple.

Some time ago, I was out with my daughter looking for a camera (digital, of course) as a graduation present. We found what we wanted and the sales clerk started to push the extended warranty which has become ubiquitous with any high-tech gadget you buy these days.

Sensing my hesitancy to get sucked in, she started talking about the complicated technology of digital cameras and how the warranty was sensible protection. "How long are you planning on owning the camera?" she asked. She said something to the effect that if you were planning on owning it for more than a few years it was an excellent investment as protection for the inevitable problems that would arise. I just about lost my self-control at that point.

It just so happened that they had a Leica M3 on a cloth draped pedestal standing all by itself in a glass showcase across the store. A dinosaur on display. It may be irrelevent that its list price was 3 times that of the digital camera we were about to buy. So I said to the clerk "You know, that camera over there has been taking photographs for 40 odd years and it will still be taking them 40 years from now. Why can't I expect the same service from a digital camera?"

She had no answer, of course, but she dropped the extended warranty pitch.

Don't worry about it. Don't fight it. Digital is the future. But don't give up on analogue either. It ain't dead yet.

Truth Beauty: Pictorialists at the Vancouver Art Gallery

This spectacular show opened at the VAG recently and runs through April 27. It includes over 150 images by some of the most important pictorial photographers of the late 19th and early 20th centuries.

Elias Goldensky
[Portrait of three women]
c. 1915 platinum print
George Eastman House Collection

http://www.vanartgallery.bc.ca/the_exhibitions/exhibit_truthbeauty.html