U of S | Mailing List Archive | alt-photo-process-l | RE: Potentially stupid pt/pd question

RE: Potentially stupid pt/pd question

> 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?

Here's the story.  I placed the order through an "authorized Legion
dealer" for the rag paper.  I got an email the next day saying that the
rag was being discontinued and replaced with the vellum.  They said that
it was "exactly the same" as the rag, so I went ahead and tried it. 
Clearly they were wrong, hehe.

> 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.

Interesting.  I've always been told more humidity = more dmax.  I'll try
one without humidifying and see what happens.

> 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.

So does heat prevent the emulsion from absorbing into the paper too much?

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

I had a printed step wedge with densitometry readings written on it.  I
used that for a comparison.

Should I be concerned about the slow clearing with this paper?  Is
doubling the clearing time the right thing to do, or should I be
increasing the strength of my clearing bath (or does it matter)?

Camden Hardy


>> -----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