Tried printing some pt/pd prints this afternoon and was disappointed in the results. I was creating a second set of prints of negatives I had successfully printed a week ago using the same process. During development the prints showed splotchy sections that look like almost perfect circles did not get either enough developer or coating. Is it me (perish the thought), the paper or whatever? A picture is in the discussion gallery. I have circled the offending areas. Would some of our alt process wizards offer their analysis, please?
Gory technical details:
Paper: COT 320 11 x 14 coated for 8 x 10 image
FO - 12 drops
NA2 - 4 drops
Pt - 4 drops
Pd - 10 drops
Single coat, rod coated, ambient air drying.
Development in PO at 95-100 F.
It looks like one of two things to me...
Either you accidentally splashed some water on the paper after it had been coated and dried (before or after exposure) or the negative had some water droplets on the emulsion side.
If the negative had water on it, or if the paper were wet when you assembled the sandwich, it would have stuck to the print a little, so you would probably have been aware of the problem, and that sinking feeling in the pit of your stomach is the realization that you just ruined a negative.
If you splashed water on the paper before, you probably would have noticed the spots in the coating if you were paying attention.They are pretty obvious as areas of lighter coloration.
My guess is before you placed the print in the developer, you accidentally splashed the surface with water. The water starts to clear the print without development (other than the printing out). Even a fewe seconds of water will ruin the print, so getting a splash on it while placing in the tray to develop could do it.
I concur with Michael in that they look like water splashes that occured after exposure but before development. I am ultra-paranoid about removing the print from my plate burner with completely dry hands. I had one instance where some water that had gotten on my developer pyrex beaker dripped on the print just before I poured the developer. So now I always have a towel handy to wipe off the bottom of my beaker.
As an aside, my 'beaker' is actually an 8-cup pyrex measuring cup with a plastic lid. I put my developer in that and heat it in the microwave. The lid allows me to minimize evaporative loss during the heating. This may be the smartest hardware store purchase I have made for my darkroom.
And I gotta put in a plug for the Richeson 9010 brush instead of a coating rod. You use it once, and you'll never want to use a rod again. It is just as parsimonious with solution volume as a rod, and it gives you much more even coats. Michael M. is a convert, I know.
Also FWIW, I have been double coating COT320 when I use it for an exhibition quality print. It definitely will improve your shadow separation and give you an improved dMax. Lately, I have been getting 1.45 to 1.5 dMax with double coating on COT.
Thanks for the help guys. Something else to watch out for.
Clay - Double coating - Add 50% distilled water to the sensitizer and use half the volume for the first coat. Let it almost dry and then put on the second coat with the remaining sensitizer?
I've been going full strength for both coats, although Michael Mutmansky has done some tests which indicate that may be overkill. I use pipettes with pumps to measure my volumes and have found that when I use a brush, an even coat takes about .2 ml of total sensitizer+metal salt per 10 square inches. For instance, an 8x10 is 80 square inches, so I use .8ml FO and .8ml Pd. The one time I measured, I got about 24 drops per ml. I may do some experimentation with diluting that first coat by 50%t and see if I notice a difference.
Don't cut the sensitizer for the second coat; it needs to be full strength.
I did some comparisons at one time and it seemed that the first coat could be cut with H2O, but it all depends on your methods, etc. If you have a particularly dark print, you may want to do it full strength to help beef up the shadows.
Double coating is nearly impossible to do well with a rod. I was never able to get a finished result that I considered satisfactory until I tried the Richeson brush that Clay mentions.
I air dry the first coat completely, and then use a hair dryer with low or no heat for the second coat. I let the second coat sit for about 5 minutes, or until it has lost the wet surface look, and then blow it mostly dry. Then I leave it for about 30 minutes to finish drying, and to allow it to equalize with the RH in the darkroom.
Works pretty well for me, but I'm just a hack with all this pt/pd stuff, so your mileage may vary.
A question concerning Joe's coating. I have been under the impression that any Pt in a coating mix containing Na2 will greatly reduce the effect of the Na2. Is this correct?
Joe I also use 2 full strenght coatings for the final print, but my drop count is lower than Clay's, I use 1.2 ml total. 8 drops FO, 6 drops PD and 2 drops PT. I second Clay's advice to get the Richeson brush, you will see a great difference from the rod.
Drying the second coat with a hair dryer like Michael said is a good idea, when I let the second coat air dry I found it was very hard to clear the print, sometimes it did not clear completely, ruinning the print.
Lallan, sodium platinate is the restraining agent itself, as opposed to sodium platinite which is the image forming metal. B&S has a good article on this if you want more information.
During a Tillman Crane workshop in pt/pd printing we suddenly got strange fogging. The problem seemed to be the combination of pt and Na2. Here's a quote from a post in another forum written by Tillman after he's done some testing.
"My conclusions are these:
Although I used the PT/PD/and NA2 combinations for a long time with
little to no problems I would not suggest using traditional PT and NA2
in the same emulsion. I was using NA2 at 5% and in very small
quantities. i think that the amount of NA2 effects the staining we saw
on the prints at the workshop. In essence I was using such a small
amount of NA2 in my emulsions the problem did not show up. But using
even one drop of NA2 in 12 drop of emulsion created the fogging effect.
So my suggestions are
1. Use the traditional contrast methods FO#1 and FO#2 and PT/ PD for
negs that are pretty contrasty.
2. Use the NA2 method for any negatives that require more then 3-3 -3-3
3. If you want to only use the NA2 method, dilute the NA2 to a 5% or a
10% solution and use 6-0-6-0 and what ever NA2 is called for."
I don't know if this fogging is a problem with just some papers or all. We used Arches plantin and Cranes kid finish at the work shop.
FWIW Dick Arentz does not have any pt in his solutions at http://www.dickarentz.com/na2.htm where he describes the Na2 method.
This has been discussed on a variety of forums lately. The consensus of the chemically knowledgable is that the regular platinum metal salt in solution effectively convetss the Na2 (pt IV) into regular platinum. This negates the restraining effect of the Na2. So it is not surprising that small dilutions of Na2 in conjunction with a lot of regular platinum in the solution renders it ineffective. Na2 ONLY works well with pure palladium prints. The reason you got fogging was that you were essentially printing with no contrast agent at all! Bottom line: if you want some platinum in your image, you gotta use another method of contrast control.