[alt-photo] Re: NuArc 26-1KS problem (Slow printing times) / Cross-post, original @ apug.org

[francis schanberger]

I have no idea how old the bulb in my 261K is but I find that with inkjet
negatives and DOP I have been working with 15-16 minute exposure times.
Don't ask me the units because I am trusting the Gralab timer in my
workflow.

Last week I did make a Ziatytype but need to dial in the humidity in the
work area and contrast in the final print.

For my light ground vandyke brown prints I aim for a 5-8 minute exposure in
the 261K.

-francis



On Fri, May 14, 2010 at 10:58 AM, Paul Viapiano <viapiano at pacbell.net>wrote:

> Loris,
>
> I'm glad you included times along with units, but as you may see from
> another thread here a few weeks ago, units are arbitrary because the NuArc
> can be calibrated many different ways. What matters most (to me) when
> comparing theses burners is times with a new bulb. That seems to get people
> in the ballpark for exposure comparisons.
>
> 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.
>
> Paul
>
>
> ----- 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>; <
> CarbronTransfer at yahoogroups.com>
> Sent: Friday, May 14, 2010 12:59 AM
> Subject: [alt-photo] NuArc 26-1KS problem (Slow printing times) /
> Cross-post,original @ apug.org
>
>
>
>  Hi all,
>>
>> I purchased a brand new NuArc 26-1KS plate burner a couple of months ago,
>> for the purpose printing with UV sensitive alternative processes.
>>
>> I've just had time to use/test it and I think there's something seriously
>> wrong with the device; I currently struggle with pop palladium (Li2PdCl4 +
>> AFO or Na2PdCl4 + AFO, noble metal solutions' concentration 0.52M, AFO
>> concentration 1.05M), and the exposure times are incredibly long.
>> (Workplace
>> conditions, 26C/77F 50% RH.)
>>
>> I was using a bank of UVBL tubes before (Philips 40W, /05 series - not
>> manufactured anymore, replaced with /10 series recently), and my standard
>> exposure time (with a 31-step tablet) was 6:30, giving me 28 distinct
>> steps
>> including dmax and paper white.
>>
>> With the NuArc, I print for 900 units (17:15), and the step tablet test
>> says
>> I still have to give 1 stop more exposure for being able to get 28
>> distinct
>> steps, and more importantly I'm currently getting a pretty anemic result
>> with low dmax. Awful. Something's wrong, WRONG!
>>
>> What is your usual pt/pd (or any other print out iron process) printing
>> time
>> (not units, time!) with this unit? (Or, similar units?)
>>
>> What could cause the problem? I'm suspecting the bulb (NP-80) but it's a
>> brand new unit and I just don't get how could a brand new bulb work that
>> much slow? (The visible light illumination is pretty strong BTW.)
>>
>> TIA,
>> Loris.
>>
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>>
>
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-- 
francis schanberger

www.frangst.com