Dmax for COT 320 using palladium

This thread sure has enlightened me and this fine tuning has been a real learning experience as well. I'm not falling into the testing vortex, although as sick as it sounds I thoroughly enjoy it. I merely want to get the most out of my materials and make the finest print that I'm capable of making. Having said that here are some things that I stumbled onto along the way....

Started with a printing time of ten minutes under a 400watt metal halide and with one coat could get steps 20 and 21 to merge. Weak Dmax though.

Double coated with 1st coat diluted as discussed and double coated with two full coats and...no difference, but the steps 20 and 21 did not merge???
I assumed that more emulsion would naturally bring printing times down. Not the case. I needed 15min to merge the steps. Now I wonder if I am experiencing solarazation?

Found the coating rod to be substandard and I still maintain that the white fuzzy hairs of the paper taint the densitometers reading. I happened to be in Downtown Chicago on business today and went into Pearl Art and bought a 2" magic brush to compliment the 3" I ordered online (Wow, what a store). I really think that will keep the paper abrasions down.

And Michael M - I'm happy with the 1.42 and will work with that. Your last response was comforting. It is a substantial improvement to what I had and will tweek little things here and there along the way. With all the little variables that come into play here I can say they are nothing compared to the 2 years I spent in an albumen haze...ee gads, talk about a loose cannon!

Mike,

Per your question on the speed of printing...

As you increse the amount of sensitized solution in the paper (think of it as a density issue, ml of solution per square inch of paper), you will slow down the printing speed of the coated paper.

This is easily testable by coating a small sheet with a very thin coat, and another with a normal single coat, and another with a double coat. The thinnest coat will be the fastest, and the heavier coats will print slower.

So the results will be the opposite of what you were expecting.

This is also a reason that the borders of prints will often solarize when printing palladium, because the borders may not have anywhere near the concentration of coating solution as the main part of the print area.

An extreme case of this speed difference is in conditions where the print was brush coated, and there may be some little wisps of brush marks beyond the edge of the primary coated area. If they are very thin wisps, the speed will be so great that they may fog even when covered with rubylith or goldenrod paper.


---Michael

FWIW.....I realize that I'm probobly preaching to the choir here but as far as the Richeson brush goes....very nice. Really nice. I fought it for a while but decided to give it a try and it's really amazing. I noticed a HUGE difference in the smoothness of the tones in the printed test wedge. Hardly any of those annoying fuzzy white hairs like I was experiencing with the rod. Thanks again!

Which brush(es) did you get and where did you get them?

Diane,

Jerry's Artarama has the Richeson 9010 for very good prices.

http://www.jerrysartarama.com/art-supply-stores/online/2101

You will probably want a 1-1/2" for up to an 8x10 image. As you go bigger, you'll want a larger brush.

Mike,

Like you, I resisted getting one because of the relatively high cost of the brushes. Now, I wouldn't consider using anything else. Keep them clean and treat them well, and they will last a long time. I stripped the laquer off the handles of mine, and then sealed the wood with waterlox because the paint on the handles will eventually start to crack, and it may foul a print with a flake.

If you haven't seen a description for how to use the brush, this is one brush you use WET. Dip it into distilled water and get it soaked. Pull it out and shake it four times onto the floor pretty hard. It should appear totally soaked and the bristles should be stuck together, but not dripping at all.

It'll take a little practice to get the right amount of H2O in the brush. Too little, and it'll soak up solution, too much, and it'll deposit H2O onto the paper as you spread the solution around. Just right, and it'll neither absorb or leave behind any water.

When it's just right, you will notice that when you wash it out, almost no discoloration occurs in the wash water.


Enjoy!


----Michael

Here is another option with good prices..got mine here.

http://www.jerrysartarama.com/art-supply-stores/online/2101

I toodled over to Jerry's in Raleigh, NC on Saturday. Lots of Brushes, no Richeson 9010 brushes in 2.5". Ordered it on the web. Wonder if the web store and the real store are run out of the same location.

No doubt about it Jerry's has some good prices.

Oh yeah, but the 9010 brushes they had there really felt nice.

Richeson 9010

The Richeson 9010 is the "magic" brush everyone is exalting? I thought that alt. process plat./pall. does not work with a metal ferrule.The metal is supposed to react with the metals in the process? Right? Wrong? I usually just buy a high quality hake brush and they work fine. Someone please clarify this for me
Regards, Peter

Peters,
There is no problem with a metal ferrule on the 9010 brush. For one thing you are not using "that part of the brush" to coat the paper. The only problem with the 9010 is the paint cracking over time and flakes falling on the coating but this is easily taken care of by removing paint from the brush or as I have done coat the handle with the rubber coating material used for hand tools.
I believe " don't use a brush with a metal ferrule" is one of those rules like " you can't use dichromate in the developer to control contrast with straight palladium". Some of those rules are just a bit out dated.

Yup, there are a lot of techical changes in what is a very old technology. So, if you don't pay attention to the technical side of things, you could be missing out on some productivity improvements that make your life easier and your photography better.