[alt-photo] Re: 3 color gum and PDN calibration?

[Henry Rattle]

Just in case it's relevant here, I found it impossible to judge the yellow
under fluorescent light of any kind. There are quite a lot of missing
wavelengths in the yellow region of fluorescent tubes/energy-saving bulbs,
so you don't get a true impression.

For the record, I use W&N Permanent Rose (PV19), Winsor Blue (Green
tint)(PB15), and Winsor Yellow (PY154) and find that yellow requires about
one-and-a-half times the exposure (12 min against 7 min) of the other two.

Best wishes to you all,

Henry


On 27/09/2012 07:17, "Loris Medici" <mail at loris.medici.name> wrote:

> Johnny, I kinda agree with the comment below.
> 
> Just for the records / for the case you may feel the need for an
> alternative method in the future:
> 
> - Calibrate for a much more simpler / stable (in terms of consistency,
> number of parameters and ease of calibration) process such as
> cyanotype, p/pd and such (shorter scale processes are better, since
> gum also has a relatively short scale)
> - Find the correct pigment-dichromate ratio, exposure time and
> development regime to suit the negative for each separations. I mean:
> Don't confine yourself into a strict set of parameters, use the
> flexibility of gum! It would be a good exercise in exploring /
> learning the capabilities of the gum process too!
> 
> Hope this helps somehow,
> Regards,
> Loris.
> 
> 2012/9/27 Mary <gneissgirl at spamcop.net>:
>> ...
>> I have to admit that after struggling with PDN for calibrating gum, I kind
>> of gave up. I just didn't have the patience to deal with it. I remember
>> yellow being particularly frustrating. I admire your tenacity!
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