[alt-photo] Re: NuArc 26-1KS problem (Slow printing times)

[Paul Viapiano]

Loris...

Good luck on your experiments. Our individual digi-negs are also a big 
variable here, although I know you said you exposed a 31-step Stouffer.



----- Original Message ----- 
From: "Loris Medici" <mail at loris.medici.name>
To: "The alternative photographic processes mailing list" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Friday, May 14, 2010 9:24 AM
Subject: [alt-photo] Re: NuArc 26-1KS problem (Slow printing times) 
/Cross-post, original @ apug.org


> Hi Paul,
>
> No, the emulsion is not solarizing (I observed the exposure
> intermittently to make sure). The paper is still limp when I take it
> out the frame, therefore it's not humidity loss. (Also, the back is
> covered with thick black impermeable plastic stuff that came with the
> unit.) I use 10 mmHg vacuum power.
>
> 18-21 for dop is longish, then I have to expect something even longer
> with pop... (Bad news!)  But current tests indicate even 35minutes
> won't be enough...
>
> My usual gum exposures were 3-5 minutes range with 5% AD and UVBL bank
> w/ very robust layers.
>
> Thanks for the info,
> I'll test the emulsions with my old lightsource, it's somewhere else
> right now. Will test tomorrow with both the sun and old exposure unit
> to make sure it's not my emulsions...
>
> Regards,
> Loris.
>
>
> 2010/5/14 Paul Viapiano <viapiano at pacbell.net>:
>> ...
>> So that being said, are you sure that the emulsion is not solarizing with
>> long exposure, giving you an anemic dMax? Also, with long times, the 
>> vacuum
>> frame draws a lot of moisture from the paper. Are you laying a large 
>> piece
>> of mylar or other thin plastic on the bed before placing your negative
>> sandwich? This will help keep the paper humidified. Isn't that a big 
>> factor
>> in pop palladium? I also use a vacuum of about 15 pounds of pressure 
>> rather
>> than let it rip all the way to 25 or 30. Don't know how much difference 
>> it
>> could make as well.
>>
>> I've found that my DOP palladium negatives need 7-8 minutes in the sun
>> (bright, clear, So California sun), but 18-21 minutes in the burner (with 
>> a
>> brand new bulb), so I'm crafting new negatives and curves to compensate.
>>
>> I also see this in my gum printing with paper negs that normally print in 
>> 2
>> minutes in the sun take 6 minutes in the burner.
>>
>> I share your frustration. I thought that a burner would just be a drop-in
>> replacement or get faster exposure times, but instead there is a lot of
>> recalibrating etc in order to maintain what I consider decent workflow
>> times.
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