Couple o platinum questions

[photomc]

Jarvman, check with one of the woodcare type shops. Some carry oxalic acid to bleach/clean wood products. Here is a link to a place I found using google and it is 8.75 inc VAT for 1Kg.

 

[Kerik]

Yeah, you need to find a chemical supplier that will sell in much larger quantities. There are many here in the states like The Chemistry Store:

http://www.chemistrystore.com/Chemicals_G_R-Oxalic_Acid.html
http://www.chemistrystore.com/Chemicals_G_R-Potassium_Carbonate.html

I buy the chems from a local place that sells pool chemicals and the like to the public.

 

[Jarvman]

ooh ooh, another thing, how many of you actually presoak your paper before coating it? Leaving it to dry out before applying the pt/pd obviously.

 

[Allen Friday]

It depends on the paper. I don't presoak unless the paper is too alkaline, in which case it gets an acid pre-soak.

 

[donbga]

Vaughn you are correct. Heating the developer releases water vapor resulting in an increased concentration.

FWIW, I use a large - 2 QT. Pyrex measuring cup with plastic lid to heat my PO. The lid minimizes evaporation and the vapor condenses on the inside of the lid.

As Kerik said filter the sludge and check the pH. Top off with fresh PO as the volume declines or add a little water to dissolve crystals at the bottom.

You are good to go.

 

[Vaughn]

Thanks, guys. I'll get some litmus paper (though I may have some around somewhere...or I'll hit up the Chemistry Dept for some) and will aim of a pH of 6...I have plenty of Oxalic acid. I have some crystals in the bottom of the jug, so I'll add a little water.

I'll have to get some more potassium oxalate, too. I spilled a little during my last printing session and I have barely enough to print with. Hate doing that, but sometimes the old brain/body connection falters in the wee morning hours.

Vaughn

PS...my guess is that my pH will be good -- I generally use an Oxalic acid treatment on my paper (soaking the paper a couple minutes in a 5% solution) before coating.

 

[PVia]

Ummm... you missed the point. Maybe I wasn't clear. You apply the tape prior to coating the paper then remove it after drying. The idea is to mask off the area to be coated, not masking over the coated area. That's what Rubylith, Amberlith or Goldenrod are for.

Yes, yes...of course!

(slaps forehead)

 

[PVia]

The way he used a tilted easel rather than laying it on a flat surface and started from the top of the print and gently lifted the top edge of the paper allowing the solution to flow down the paper. This he did in sucessive brushstrokes down the paper until it began to pool at the bottom then he began to draw the excess away with the same brush where the tape was and drain it back into the pot. The coating was exceptionally even though. Apparently there is a slight difference in exposure at the bottom but this must be factored in when printing. Obviously everyone has their own way of doing things but this seems to work for them. He was quite blase about humidity really. There was a humidifier in the room but obviously when you're that good you're totally intuitive about the process. The paper they use 90% of the time is arches aquarelle. I was in complete awe being there.

This sounds similar to the way a watercolorist paints a wash...

 

[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...?

 

[Davec101]

This sounds similar to the way a watercolorist paints a wash...

Paul Caffell was a painter before he was a platinum printer and he still does paint too, so that kind of makes sense

 

[MVNelson]

for what its worth I like working with ammonium citrate because at room temp it seems to be very consistent. I'm told pH is less a deal, just add fresh solution to keep your vol up. With pure pd I think the color is warm enough for much of what I do. What I do like about ammonium citrate is that with a little Na2 with pd you can get some very nice subtle colors. However if the Na2 conc goes up for need of increasing contrast control then the prints seem to get increasing cool in color. I think ammonium citrate is a tad healthier to work with also. That said I use pot . ox. about 40% of the time.

Miles

 

[Jarvman]

Paul Caffell was a painter before he was a platinum printer and he still does paint too, so that kind of makes sense

Except it was Dominic who I was watching make the prints but he probably got the technique from Paul I would imagine. Some real nice work coming out of your workshops Dave. I'd like to try running something like that in future down this way. Thanks Miles, I'm just going to go ahead and use the citrate. Need to just get stuck in and try it this week.

 

[Tom Kershaw]

Jarvman,

You're thinking about running workshops in pt/pd printing?

Tom.

 

[Jarvman]

Not any time soon Tom, haven't even made the first print yet! Thinking way ahead now. But it's an idea for years to come. There's a perfect place called Swansea Print Workshop that does screen printing and cyanotypes and I could see it fitting in there really nicely. Gotta think of all the different sidelines I can. It's inspirational seeing someone else doing it.

 

[Tom Kershaw]

What have been your main printing interests so far?

Tom.

 

[donbga]

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.

 

[scootermm]

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.

 

[Jarvman]

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

 

[PVia]

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...

 

[Jarvman]

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

 

[TheFlyingCamera]

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.

 

[Jarvman]

Don't have a choice... It's this http://www.bostick-sullivan.com/cart/product.php?productid=855&cat=49&page=1
Perhaps I should've got the classic kit. Does anyone have experience with using this?

 

[photomc]

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.

 

[TheFlyingCamera]

Don't have a choice... It's this http://www.bostick-sullivan.com/cart/product.php?productid=855&cat=49&page=1
Perhaps I should've got the classic kit. Does anyone have experience with using this?

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.

 

[Jarvman]

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