[Alt-photo] Re: Stochastic screening in Gum

[Christina Anderson]

Dear Peter,
I have done this for the reason of trying to approximate an autochrome. Gum surprisingly prints great detail so if you are trying to grain up a print, it works. I have also done gum printing with a bitmap negative with the bitmap quite coarse, and also with adding noise to the channels individually. What i notice is that the contrast does go down and I think you therefore could get by without curving the gum negative to be lower contrast. It produces a very soft, very minute grainy look. It was something I thought intriguing enough to explore but never got back to it. What I did was print the image regularly and then also with grain so I could see the comparison side by side. I didn't see an advantage to it technique-wise, only the way it looked--minute grain. But I find that minute grain is also part of casein's charm. It's not the grain you get when a gum print goes awry, but much smaller and deliberate.
It also made me realize that a regular bitmap negative is just fine for gum whereas it might not be good for other one-step processes like platinum or VDB.
Chris

Christina Z. Anderson
http://christinaZanderson.com/

On Dec 6, 2013, at 4:21 PM, Peter Friedrichsen wrote:

> Has anyone applied a stochastic screen to gum printing? This is a half tone technique that uses dot frequency to emulate color/greyscale. The smaller the dot size, the more photographic the rendition. My UV box generates diffuse UV light so I think that may not be as effective as a more point sourced arc type UV lamp.
> 
> Has anyone done anything like this before? I was wondering what the minimum dot size that could be realized from a contact negative?
> 
> Peter Friedrichsen
> 
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