[alt-photo] Re: Gum over cyanotype question

[C.Breukel at lumc.nl]

Loris,

I think it was Marek actually, but I agree completely, this bleach back technique is very useful, I even used it on bullet proof Pyro negatives, tailored to Pt printing..

Best,

Cor

Ps let me plug again a page I did make onit:

http://members.casema.nl/cordieuwke/GumOverPlatinumII.html

> -----Original Message-----
> From: alt-photo-process-list-bounces at lists.altphotolist.org [mailto:alt-
> photo-process-list-bounces at lists.altphotolist.org] On Behalf Of Loris
> Medici
> Sent: woensdag 29 februari 2012 16:28
> To: The alternative photographic processes mailing list
> Subject: [alt-photo] Re: Gum over cyanotype question
> 
> For the records / reminder for everybody:
> 
> There's a very nice way of doing one coat gums with "convincing
> blacks"; mixing a highly pigmented gum emulsion rich of dichromate and
> giving it a hard exposure then developing in very mild bleach
> solution. (Or you just give a kick-start to the development in bleach
> solution and then continue in water...) It works like a charm! I think
> it was (again) Alberto who coined this few years ago, but I maybe
> confusing the person. Another **very useful** trick I have learnt
> here!!! :)
> 
> Regards,
> Loris.
> 
> 
> 29 Şubat 2012 16:38 tarihinde Christina Anderson <zphoto at montana.net>
> yazdı:
> > ...
> > Interesting you have not found prolonged exposure necessary with black.
> My guess is your black layer is thinner/less opaque than mine. An old
> pictorialist tradition was to use a thick gum/highly pigmented black layer
> with super long exposure and then good development to get one-coat gums. I
> find the trick is to use enough black for density but not too much because
> flaking occurs. I have not yet mastered this, though...on my list of
> things to do. With the one coat--no sizing, no shrinking, and if I
> remember Buxton/Ashton Platinum was the recommended paper when this
> discussion was going on.
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