Contrast & Increasing Dmax with Kallitypes

[menglert]

Hello,

I want to see if I understand increasing contrast with Kallitypes. If I make two emulsions, one with normal contrast, and one with an increased contrast then: coat them both on the same paper, but different sections, while exposing, the increased contrast solution will obtain Dmax faster than the normal solution, correct?

Also, aside from double coating, Tween 20, and toning, does anyone know of some methods to increase Dmax with Kallitypes?

Regards,
Martin

[sanking]

Hello,

I want to see if I understand increasing contrast with Kallitypes. If I make two emulsions, one with normal contrast, and one with an increased contrast then: coat them both on the same paper, but different sections, while exposing, the increased contrast solution will obtain Dmax faster than the normal solution, correct?

Also, aside from double coating, Tween 20, and toning, does anyone know of some methods to increase Dmax with Kallitypes?

Regards,
Martin

Martin,

Normally there is an optimum mixture of FO and SN that gives maximum Dmax. Depnding on your chemistry this could be a 1:1 mixture of the two, 1:2 or 2:1. Play around with this.

The other methods of optimizing Dmax are double coating, workings in conditions of relatively high humidity (60% or more), and choosing a paper with a fairly heavy size. You could also try coating a sheet of fixed out photographic paper, matte works best, but this will take a lot of trial and error to work out. The best two papers out of the box for Dmax are COT 320 and Arches's Platine.

About the most you can expect in terms of Dmax is a reflection reading of about log 1.55.

Sandy King

[menglert]

Martin,

Normally there is an optimum mixture of FO and SN that gives maximum Dmax. Depnding on your chemistry this could be a 1:1 mixture of the two, 1:2 or 2:1. Play around with this.

The other methods of optimizing Dmax are double coating, workings in conditions of relatively high humidity (60% or more), and choosing a paper with a fairly heavy size. You could also try coating a sheet of fixed out photographic paper, matte works best, but this will take a lot of trial and error to work out. The best two papers out of the box for Dmax are COT 320 and Arches's Platine.

About the most you can expect in terms of Dmax is a reflection reading of about log 1.55.

Sandy King

Thanks Sandy... I'll have to get back to testing in the coming weeks. I'll test some of the suggestions you had and see how it turns out.

-Martin