RE: Potentially stupid pt/pd question

[Eric Neilsen <ejnphoto@sbcglobal.net>]

So it is only happening on the new vellum Coventry?  If there is no fog, as
you can see with the edge test, you may not need to test your ferric for
ferrous. The way to do that is to take a 25ml sample of distilled water and
add generous pinch of Potassium Ferricyanide to it. Now take a drop or two
of the ferric and put them in the solution. It should appear brown, if it
shows blue, your ferric has ferrous in it. 

If the paper that I sent you is not showing the same signs, then you must
suspect that paper from your mystery supplier.  

Do add a few grams of oxalic acid to your developer. Filter it, and see what
happens after you make those changes.


I process my prints for 2 to 5 minutes and as Clay suggested to you, one can
use the longer times on paper that show a bit more ability to hold on to the
ferric/ferrous regions of the coating solution. I then use ?? depends on the
paper and where I am processing. Papers that clear more easily can get a
light rinse with distilled water. Then I clear in an acid, citric more than
others but also, phosphoric, oxalic acid, or rarely HCL. The prints then go
into an EDTA / Sodium Sulfite bath. Di sodium first than tetra later. A 5 to
10 minute per bath is used. With a 1/2 hr water wash. Rolled face down on a
sheet of glass, and screen dried face up. 

Standard mix for the edta/sodium sulfite is 15g of each per liter of water
used, but can go up depending on paper.  I have also used Heico's  perma
wash which has ammonium sulfite as a last wash and as a treatment for prints
that showed yellowing over time. It worked quite well. 

Eric 
 

Eric Neilsen Photography
4101 Commerce Street
Suite 9
Dallas, TX 75226
http://e.neilsen.home.att.net
http://ericneilsenphotography.com
Skype ejprinter
> -----Original Message-----
> From: Camden Hardy [mailto:camden@hardyphotography.net]
> Sent: Monday, October 16, 2006 11:13 PM
> To: alt-photo-process-l@usask.ca
> Subject: RE: Potentially stupid pt/pd question
> 
> > Did you print with clean edges so there is a way to check for fog?
> 
> I did.  There isn't any visible fog on the test print.  Paper white on the
> step wedge matches (visibly, at least) paper white where the paper wasn't
> coated.
> 
> I'm fairly sure it's something in the developer and not my ferric because
> I just used it on the sample you sent me the day before.
> 
> 
> > Have you run a ferrous test on your ferric oxalate?
> 
> How would I go about doing this?
> 
> 
> Camden Hardy
> 
> camden[at]hardyphotography[dot]net
> http://www.hardyphotography.net