Re: Pd with dichromate contrast control
Hi Camden, No, I could not tell you how much to add, but it would be a very small amount. If I were gong to test this I would try a 1% AD solution and see what would happen with 6-6-1 rate (6 drops FO + 6 drops PC + 1 drop of the 1% AD solution. But I could be way off on this. I know that adding one drop of a 5% solution of 2ml of combined FO+PC has a very significant impact on contrast. Sandy At 11:08 AM -0700 12/14/06, Camden Hardy wrote: Sandy, Thanks for the information; that was just what I was wondering about. I've got a surplus of ammonium dichromate that I've been looking to use up. Just out of curiosity, do you have any estimates as to what ratio of 5% dichromate I would have to add to my sensitizer (instead of the developer) to get roughly a 2s mix? Camden Hardy camden[at]hardyphotography[dot]net http://www.hardyphotography.net On Thu, December 14, 2006 10:58 am, Sandy King wrote:Camden, Any of the dichromates can be used, and when used at the same percentage solution will give similar results. I don't recommend sodium dichromate for most applications because of its deliquescence, and its greater solubility offers no advantage in this application so far as I can see. Sandy At 10:50 AM -0700 12/14/06, Camden Hardy wrote:Thanks for pointing that out, Mark; somehow I missed it entirely. Too obvious, I guess. :) However, the book only talks about sodium dichromate. I've heard potassium dichromate mentioned here before (was that you Sandy?). Am I just imagining the use of ammonium dichromate? I thought someone mentioned it in the Ware/Malde POP discussion (the search function of the recent archives is down at the moment, so I can't verify it). Camden Hardy camden[at]hardyphotography[dot]net http://www.hardyphotography.net On Thu, December 14, 2006 10:35 am, Ender100@aol.com wrote:Camden, Dick has such a conversion chart in the second edition of his book. Best Wishes, Mark Nelson Precision Digital Negatives - The System PDNPrint Forum at Yahoo Groups www.MarkINelsonPhoto.com In a message dated 12/14/06 11:22:46 AM, camden@hardyphotography.net writes:I've been using the Dick Arentz method of pd contrast control with various concentrations of the Na2 solution. I'd like to try printing pure palladium with ammonium dichromate for contrast control, as I've heard someone mention in the past. So my question is, how does one method translate to the other? What kinds of quantities/dilutions of am. dichromate would I need to use to get comparable contrast results to Arentz's 1s/2s/3s solutions? I realize this is an apples/oranges question before asking it, but I'm having trouble finding a better analogy. :) Thanks, Camden Hardy
|