U of S | Mailing List Archive | alt-photo-process-l | Re: again on color absorption

Re: again on color absorption

Light source and other chemicals in the sensitizer are ever interacting with the sensitive substance, so that the effective wavelength can be shifted from the optimal one (that is, the wavelength where the sensitive substance has its maximum quantum yield).
For example, it would be interesting to compare HSB cyanotype tests with two different concentrations of ferricyanide (for example, 25% FeAmCitr. + 12% or 25% K ferricyanide), and a cyanotype Rex and a kallitype which does not have K ferri in the sensitizer (ferric oxalate). With the first two, one will see (and will be able to calculate) the masking effect of ferricyanide, whilst with the last two one should see almost equal tests.