Re: Contrasting agents

[Tom Ferguson <tomf2468@pipeline.com>]

There are curves in Dick Arentz's book (at least the early version I have).
>From experience I believe that the contrast agents do work correctly in
platinum, but the ones I tried in cyanotype simply decreased d-max rather
rather than truly altering contrast.
-- 
Tom Ferguson
http://www.ferguson-photo-design.com

> From: Monnoyer Philippe <monnoyer@imec.be>
> Subject: Contrasting agents
> 
> Hello Folks,
> 
> Is a contrasting agent in Pt/Pd processes (or even cyano) just working
> as an oxidizer ? Meaning that it reduces the density evenly on the
> print, and as the concentration is low, the reduction is low too. This
> gives burned highlights. Isn't it more a reducer than a contrasting
> agent ?
> I would expect a contrasting agent to boost the high densities.
> 
> Does one of you have Pt/Pd DlogE curves and experiments to share about
> it ?
> 
> Thnak you,
> 
> Cheers,
> 
> Philippe