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 Originally Posted by PVia
Should ammonium citrate be treated the same way as PO (mentioned in a previous post), ie, checking its ph and adding oxalic acid to keep it acid...?
Yes! Keeping the developer pH slightly acidic makes the print easier to clear.
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Originally Posted by PVia
Should ammonium citrate be treated the same way as PO (mentioned in a previous post), ie, checking its ph and adding oxalic acid to keep it acid...?
In addition to what Don just said PVia, when you need to make sodium citrate more acidic... you use Citric Acid. Sodium Citrate is Sodium salt (carbonate etc) and Citric Acid.
Whereas with Potassium Oxalate you add Oxalic Acid as its made up of Potassium Carbonate and Oxalic Acid.
Nigel Tufnel: It's like, how much more black could this be? and the answer is none.
None more black.
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Gah, could anyone help me. I'm having some big trouble with this. I'm trying to work out my exposure by making a test strip through pictorico. The first one seemed to work ok but wasn't dark enough at 7 mins so next I tried a test strip with increments of 7 mins upto a maximum of 49 mins and the thing solarised, brown and patchy pretty much the whole way through. I phoned B&S and they don't really know how to help me out. This is using the NA2 kit, 10 drops ferric oxalate, 10 drops pd, one drop pt on arches platine coating with a rod, trying to print a step table marginally bigger than 4x5. Not sure what to do. I think its down to my shoddy coating technique. It's going on too thin I reckon 
Last edited by Jarvman; 03-02-2009 at 07:35 PM. Click to view previous post history.
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Jarvman...
What light source are you using? If sun, how bright is it outside?
What are you using for a test strip negative? A step wedge or something else?
Are you using Ferric Oxalate #1?
You mention NA2...did you use any of it in the solution?
Also, make sure your contact printer glass is not anti-UV.
Keep things simple, stick with pure palladium for now.
6-7 minutes in bright sun is standard for a perfect print in my neck of the woods...
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I'm using 9 25W blacklight bulbs in a box much the same as the one Trevor Crone showed me in another thread
It's a step tablet printed on pictorico film for the purpose of making an adjustment curve
Like I said, 10 drops ferric oxalate #1
The NA2 is mixed in with the platinum, sodium chloroplatinate it is. I'm using one drop of this
The glass is definately fine, its a printing frame supplied by B+S
I don't seem to be achieving a good black, I think its down to spreading the solution too thin. How black should i be expecting it to go? Using pure palladium aint a bad idea for now. hmm
Last edited by Jarvman; 03-03-2009 at 05:13 AM. Click to view previous post history.
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Jarvman-
A word to the wise- if you are doing pt/pd mixed prints, you are throwing away your money using NA2 as a contrast agent. I learned this lesson the hard way. If you want to use NA2 for contrast control, stick to pure palladium. If you are going to blend, then you have to use either the A+B method (ratio method) or dichromate in the developer.
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Don't have a choice... It's this http://www.bostick-sullivan.com/cart...&cat=49&page=1
Perhaps I should've got the classic kit. Does anyone have experience with using this?
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The kit you listed has all you need to process like the classic kit. The Na2 is optional, so using your drop count you can start off using 10 of FO + 10 of Pd. The Na2 is most likely 20%, do yourself a favor and take 1/2 of that amount (5ml) and put it in a seperate bottle with 5ml of distilled water (now you have 10 ml of 10%) take 5ml of that bottle and move it to another bottle add 5ml to it and you will have 10ml of 5%, do the same thing and you will have 10ml in a bottle that is 2.5%. At this point you will have the 4 bottles - 5ml @20%, 5ml@10%, 5ml @5% and 10ml@2.5%. Most of the time you will use the 2.5%, or you can dilute it down even more so you have 1.25%.
As to your blacks, what paper are you using? Paper and the amount of humidity in it will have as much affect on your blacks as anything else. Also, what do the blacks look like that surrond the test strip - are these black? Also, what are you using to coat the paper with - coating rod or brush? Try a practice run, using water (add a little food color if it helps you see what you are doing). Check the paper, it could be one that has a side A and B - meaning one side is much better for coating, the other is not. It could also be a paper that needs a bath in oxalic acid, which can also make a difference.
There are lots of variables going on...it takes a little time, but one day it all comes together and starts to fall into place. Of course there are days where the gods are unhappy and not matter what you do (or how long you have been doing it) everything turns out wrong 
You have gotten good advice in this thread from the likes of Kerik, Scootermm, Don and Vaughn to name a few. These guys are good, so check other threads and see if they haven't covered this before.
Good luck, but most of all Have Fun.
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Originally Posted by Jarvman
Jarv-
if that's the kit you're using, then you're fine using NA2 as a contrast agent. Your previous statement gave the impression that you were using a combination of platinum and palladium. Since you are only using palladium, then you can continue to use NA2 for contrast control.
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No no, I am using a combo of platinum and palladium, but the NA2 is mixed in with the platinum. It's called sodium platinum solution. It's used as a contrast agent instead of ferric oxalate no.2. Rather you just use ferric oxalate no.1 and leave out the no.2
Last edited by Jarvman; 03-03-2009 at 10:02 AM. Click to view previous post history.
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