[alt-photo] Re: NuArc 26-1KS ideal vacuum pressure?

[david drake]

I also just got my NuArc 26-1K working this past weekend.
I am only getting a maximum of 12 which concerned me, but from what  
I'm hearing here that's plenty.
That's a great idea about the backing Jeremy.

thanks
david


On 6-Apr-10, at 9:23 AM, Jeremy Moore wrote:

> I use ~9, but that's assuming my dial is accurate. Any higher than  
> this
> setting and I don't get any increase in sharpness so I've just left it
> there. You should also be sure your emulsified paper/negative combo is
> backed by something to help keep the moisture from being sucked out.
>
> -jeremy-
>
> On Tue, Apr 6, 2010 at 3:08 AM, Loris Medici  
> <mail at loris.medici.name> wrote:
>
>> Hi all.
>>
>> Yesterday, I finally managed to have my new NuArc 26-1KS installed.  
>> Pretty
>> exiting, seeing the vacuum bed operate was a real eye opener; I will
>> finally
>> be able to make sharp prints sized 12x12" / 11x16.5" or 12x16".  
>> Plus, the
>> light integrator is a real bliss.
>>
>> My question is, what is the ideal vacuum pressure for the following
>> processes? (If the concept isn't a total nonsense, that is...)
>>
>> - Iron / iron-silver processes: Cyanotype, Vandyke / Argyrotype and
>> Pt/pd...
>> - Dichromated colloid processes: Gum Dichromate, Casein and Carbon...
>>
>> As we all already know, humidity level and/or maintaining an absolute
>> minimum of humidity in the paper/emulsion is essential for making  
>> those
>> processes work successfully. Therefore, I fear of using too much  
>> vacuum and
>> to cause humidity escape from the paper/emulsion.
>>
>> I'm thinking something around 10 mmHg... ???
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david drake photography
www.daviddrakephotography.com