Paper for Alt Process and Pt/pd printing

[Cletus]

So it looks like I'm finally getting geared up to do some pt/pd printing. Got my UV box on the way, have a printing frame and I think everything I need but the paper, chemistry and coating rods / brushes. The paper is what I'm wondering about now - I know Arches, Stonehenge and some others made specifically for alt process are sold at Bostick and Sullivan, but I've also been given to understand that most of this type of paper is really just fancy watercolor paper which has been "optimized" for lack of a better word, for photographic coating and printing. How similar is this paper compared to normal, fiber based silver gelatin paper, surface-wise?

I'm asking this now, because I'm wondering whether I can just go over to Michael's or Hobby Lobby and get some plain old watercolor paper to practice on? I can't imagine what the surface composition of proper alt process paper must be like, in that you can put a small amount of fluid on it and spread it all around and it doesn't just soak right in? Isn't water color paper similar in texture and surface to blotter paper? And then, after processing the print needs to be washed for an hour or so, same as you would a FB gelatin silver print. Wouldn't watercolor paper just turn into mush after a few minutes in an archival washer?

I know that at some point (soon) I'll need to actually just get the right stuff and try some of this for myself, or maybe even invest in Dick Arentz' book. In the meantime though, I was hoping to get a little guidance from some of the alt process printers here. I have some "Liquid Light" emulsion to fool around with and practice my coating skills with and I'm guessing this stuff wouldn't be that much different from coating the pt/pd mixture, or other alt process chemicals? I plan to use either a Hake brush or glass rod. I've never done any of this before, so don't know which will be best for me.

So I guess my main question(s) is: What is unique about paper designed for alt process? What's the surface composition like compared to watercolor paper (or normal FB enlarging paper) and will ordinary watercolor paper serve as a substitute for practice and hold up in the washer okay?

I'm excited about finally getting into some platinum and alt. printing, but have a little learning curve to negotiate here first! Thanks for your advice.

[BarryS]

You might start off printing some cyanotypes or Van Dyke Brown prints to get your feet wet. Better to perfect your coating and printing techniques with cheap chems and be ready when you start playing with precious metals. Liquid emulsion is very different from working with the water-like Pt/Pd chems. See if B&S still offers sampler packs of paper. Many alt-processes are very finicky about paper quality and you could waste a lot of time and money trying random papers at your local craft store. Some papers that work fairly well for Pt/Pd are Revere Platinum, Arches Platine, COT-320, and Weston Diploma Parchment. They're all 100% cotton rag papers with no alkaline buffering agents to mess up the chemistry. They're also sized to retain dimensional stability when wet. These are essentially watercolor papers that are process-friendly and go though additional quality assurance to make sure they work correctly with Pt/Pd. Despite that, they tend to vary from batch to batch, so there's no substitute for testing in your process.

I highly recommend Dick Arentz's book--it's invaluable for the Pt/Pd process.

[cyrus]

You can indeed use this for watercolor paper. They can be used for a variety of artistic applications other than watercolor or ptpd printing. Etchings, for example. It is really a matter of personal taste. They're not dedicated solely to pt/pd.

Of course you can't really compare this to photographic paper because these don't have the emulsion coating.

I remember a workshop on cyanoprinting that involved using these fancy papers. I decided to try out the cheap, industrial-strength paper towels that were distributed around the darkroom instead. The results were far better than the more expensive art paper. So really it is a matter of personal taste. Just try out different papers until you like one.

Liquid Emulsion is much thicker consistency than ptpd solutions. Coating really isn't all that hard -- you'll get the hang after your 2nd or 3rd try. I prefer rods over brushes because brushes CAN cause the paper surface to rise up & I think brushes soak up the expensive pt solution too much

[Dennis]

Paper for PT/PD printing must be internally and externally sized. Art stores have that information about their papers. Also the paper should not be alkaline or buffered with some alkaline buffer.
You can get by to learn with some water color paper from any local art store if you are willing to do a quick pre treatment to fix the ph.
You can get regular Arches 90 lb hot press watercolor paper and then pre treat it with a weak Oxalic Acid solution... which is to say maybe 2% Oxalic Acid in water. Oxalic Acid is cheap.
Pre treating the paper is a matter of getting it wet with the Acid and then letting it dry. You can brush it on or put it in a tray and immerse the paper for a minute or so and then hang to dry.
After that you will have a paper that will give acceptable results.
Another common paper in an art store is Rives BFK. It has a bit of texture but if you give it the Oxalic Acid treatment it gives very nice blacks and a nice print.
Dennis