[alt-photo] Re: pd/pt coating solutions

Eric Neilsen ejnphoto at sbcglobal.net
Wed Mar 30 19:32:34 GMT 2011

David, I am saying don't add it at all. And  now that you are talking about
digital negs, a very small amount may be needed. Just as with photoshop
workflows where one needs to know the whole thing, hardware type and
software versions, before offering up to much "do it this way", it is
important to know others entire process to put the mixture into perspective.

Potassium Chlorate does indeed make images have contrast, but even in slight
amounts can produce pronounced grain. IS that a problem? Not for some, and
that's visually speaking. You may have been told you MUST add a little to
keep the fogged highlights down. That may be or not. 

Nomenclature 101 - Not everyone prints with the B&S chemicals, nor Dick
Arentz method or... so Ferric Oxalate can come in a powder or liquid form.
It can be home made in either type. I make a liquid. I have gone from Pot
Chlorate, H2O2, tried Dichromates, (sodium, potassium, ammonium) in separate
solutions and at different concentrations in the developer. I currently use
the platinic acid method that B&S users might refer to as Na2. All the
methods that restrain the highlights can be looked at for you preferred
workflow. Several can be made as separate solutions and added to the coating
solution just prior to coating the paper. Some can be added to the ferric
prior to the drop count time and you just end up with more solutions to add.

If you are using solution two, in the B&S system, then that is where the
chlorate comes in and the chlorate has more effect on some solutions than
others. The balance is in PD and PT for color and contrast. The additional
contrast changes come from gold and how it reacts with pd, pt and any other
parts; say lithium. Each new concentration and balance of pd, to pt to
sodium, to ammonium, to lithium changes the retainers that one might use. 
Any change in your pt, pd ratio, as well as a change in humidity and any
additional additives like gold will benefit changes.  The changes to be made
will be depend on what you want to see. 

Eric Neilsen
4101 Commerce Street, Suite 9
Dallas, TX 75226

Let's Talk Photography
SKYPE ejprinter

-----Original Message-----
From: alt-photo-process-list-bounces at lists.altphotolist.org
[mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of
David Ashcraft
Sent: Wednesday, March 30, 2011 12:50 AM
To: The alternative photographic processes mailing list
Subject: [alt-photo] Re: pd/pt coating solutions

On Mar 29, 2011, at 9:20 PM, EJ Photo wrote:

> David, I would first try it WITHOUT the chlorate in either case.
I'm assuming when you say without that you're suggesting that the  
chlorate be added to the ferric solution just before printing?  Or...  
what method are you using?

> it does add some graininess so test the look without it first and  
> see if it
> works for you.
Not sure how to mix coating solution #2 without Chlorate since it is  
the only difference from sol. #1?
> Pot Chlorate can be added as a separate solution too.
How does one do this?
> the percentage solution is the key.
This is why I made the post, to find out what others have used and if  
and when adding the gold is there any benefit to adjusting the  
Chlorate in sol. #2?

> What are you doing about the PD and PT
> solutions? ordering them in powder too?
I have only ordered PD and PT in solution so far but I'm looking into  
the powders.

I'm fairly happy with my prints but am always looking for ways to  
improve them.  Still photographing with film but printing with digital  
negs.  Most of my prints are made with 1:1 solution #1 and #2 and if  
not just a slight drop change.

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