Humidity control and Pt/Pd

[Paul]

I was wondering if anyone had some advice for winter printing in Pt/Pd. I was hoping to try my hand at the Na2 method in a bit. My problem is that my "darkroom" is half of my basement and this time of year in the Frozen North, the relative humidity in my house is below 30%. Last year winter when I was doing kallitypes I experienced some graininess in many prints and I am pretty sure it was related to low humidity.

I could try a humidifier, but I am not sure how effective that would be in a 30'x16' basement area that is not tightly sealed. I could construct a humidification chamber of some sort, but am not quite sure how best to do that or whether it would be ideal.

Has anyone successfully dealt with a similar predicament?

Thanks,
Paul

[dpurdy]

I am not sure if my method is best but I set up an electric fry pan (that has never been used to fry) with water at about 180 degrees and when I take the lid off it lets out a bellow of steam. I steam a paper before I coat it then let it sit for a short while. Then after coating it I wait a bit longer than usual for the sensitizer to soak in and then dry it with a hair dryer. Then I re steam the coated paper and put it on a dark shelf and let it sit at least another 10 minutes for all the paper fibers to be able to become equal in moisture content. If you can work out your routine to let it sit a half hour at this point it is even better.
anyway that is what I do.

[clay]

If you just want a temporary solution, check out the recommendations by Mike Ware on his web page (here :http://www.mikeware.co.uk/mikeware/P...ladiotype.html ) and go to the humidification section. You could easily construct a chamber from a waxed or sealed cardboard box with a shelf in it to support your paper above a pan of water containing one of the saturated solutions he lists in the article. Ammonium chloride is pretty cheap and available, and would allow you to maintain an 80% humidity level in a sealed box of some sort. The procedure would be to coat and let the paper rest in the box until exposure. The Ware process is interesting in and of itself, but is highly sensitive to humidity differences. I have managed to get a unique rich nut-brown color using the the Ware chemistry and a 35% humidity level. If you can lock down your variables, it is a very beautiful approach to printing in palladium.

[Paul]

Thanks. Those are both good suggestions. I think I may try a humidifier placed close to the coating and exposure area to see if I can create at least a small area where the humidity is higher than typical room levels.

[Blunt]

I use a Sunbeam humidifier to help raise rh in darkroom and to humidify the paper after drying the coated paper. Sometimes the rh in my darkroom gets down to about 35% and I can still print with success. I don't pre-humidify the papr before coating but I let the coating rest a few minutes before putting it in the drying chamber for four minutes. Then I hold the paper over the mist, about a foot away from the machine and keep paper moving for 60 seconds. Seems to work for me.

[Paul]

Thanks. I think that is what I am going to try, since it seems to be the simplest place to start.

[Dan Dozer]

I do it a very inexpensive way. I got a cheap humidity guage on Ebay which is about the size of a calculator and reads both the humidity and temperature. Then I got a big plastic storage bin from the local home store (got mine at Lowes) and made a wood frame with a fiberglass screen slightly larger than the inside bottom of the storage bin. Since the bin sides are slightly tapered, the screen sits about 2 " above the bottom of the bin. I put about a gallon of warm water in the bin, put the paper on the screen in the bin, put the humidity guage inside the bin and put on the top. It only takes the inside of the bin about 15 or 20 minutes to get up to over 60% humidity. The warmer the water, the faster the humidity raises. Note that I live in the Desert South West where humidity is very low most of the year.

[Paul]

Dan,

That sounds like a very simple solution and one that I might employ.

Thanks!

[dpurdy]

It is called a hygrometer.

[Dana Sullivan]

I find that elaborate humidity chambers and controls are overkill. I just tell my customers to coat their paper with distilled water or 10% oxalic solution and let it sit until it's about 90% dry before putting emulsion down. If you're trying to get water into the fibers of the paper, I don't see any reason to jump through hoops by controlling the ambient humidity. You're not trying to trick the paper into having water in it, you don't have to sneak up on it and surprise it. Just put the water on the paper and forget about the circus tricks.

-Dana