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 camden[at]hardyphotography[dot]net http://www.hardyphotography.net > >> -----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 >> >> > > > >
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