[alt-photo] Re: Gum over cyanotype question

[Alberto Novo]

I don't remember if I suggested this, though I used it with profit with 
casein which is harder to develop than an hard gum. 

Alberto 

> 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 .ubat 2012 16:38 tarihinde Christina Anderson <zphoto at montana.net> yazd.:
>> ...
>> 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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Alberto
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