U of S | Mailing List Archive | alt-photo-process-l | Re: was Miracle size for gum now tonal range

Re: was Miracle size for gum now tonal range

On Oct 11, 2009, at 12:04 PM, Katharine Thayer wrote:

I have a demonstration on my website showing what happened when I compared ammonium dichromate at saturated concentration vs ammonium dichromate cut to 1/5 of saturated concentration, and exposed accordingly (it took 5x the exposure to properly expose the dichromate at 1/5 the concentration). The actual experiment involved five different concentrations showing a linear relationship between concentration and exposure, but I only showed the two outside conditions to save space on the website. The 5x diluted dichromate printed only four steps, vs eight steps for the saturated concentration.

Link if anyone's interested: