RE: Potentially stupid pt/pd question

[Eric Neilsen <ejnphoto@sbcglobal.net>]

Why did you go with the Vellum and not the RAG? When they say they are the
same, did you ask about "whiteness", weight, ??  Whom at Legion did you
speak with?


Dmax can be compromised by not enough coating for a paper and by letting in
soak in to deep. It may be a material that likes a lower humidity to start
with for coating.  

The pH of the substrate is only one factor in coating paper. This paper may
need to have a more direct air stream or heat applied to it during the
drying process.   

How are you guessing .9? Black paper with two holes with one over the known
value and one over the unknown value? 
 

> -----Original Message-----
> From: Don Bryant [mailto:dsbryant@bellsouth.net]
> Sent: Friday, October 13, 2006 6:47 PM
> To: alt-photo-process-l@usask.ca
> Subject: RE: Potentially stupid pt/pd question
> 
> For clearing try using a 3 % solution of citric acid for 5 minutes
> directly
> after the developer without a water bath. Clear in Kodak hypo clearing
> agent
> @ a 1:3 dilution from stock for 5 minutes in the next two baths. Wash.
> 
> 
> -----Original Message-----
> From: Camden Hardy [mailto:camden@hardyphotography.net]
> Sent: Friday, October 13, 2006 7:10 PM
> To: alt-photo-process-l@usask.ca
> Subject: Potentially stupid pt/pd question
> 
> I started calibrating my new shipment of Coventry Rag Vellum paper, which
> Legion assured me was te same as their Coventry Rag (thanks to Eric for
> the recommendation and sample).  Right out of the box, I could tell you
> that it's not the same.  But I swiped it with a pH pen, and at least
> looked acidic enough for pt/pd, so I decided to give it a try.
> 
> I'll start with my workflow.  I pre-humidified the paper at 55% RH for a
> half hour, coated, then let it dry in 55% RH for another half hour.  I
> exposed a 31-step tablet for 6 minutes, developed in potassium oxalate
> (100 degrees F), cleared in hypoclear+EDTA.  This has been my normal
> workflow and until now proven to work well.
> 
> Now here's what I'm encountering.  First of all, the Dmax is nowhere near
> what I would have expected.  I don't have access to a working
> densitometer, but I'm guessing it's about 0.9.  The other issue is that it
> took twice as long to clear as any other paper I've used.
> 
> So here's my question.  What are the possible causes for this?  Are these
> issues independent of each other, or could they have the same cause?
> 
> Thanks,
> 
> Camden Hardy
> 
> camden[at]hardyphotography[dot]net
> http://www.hardyphotography.net
> 
>