Humidity control and Pt/Pd

Paul · Jan 14, 2009

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 · Jan 14, 2009

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 · Jan 14, 2009

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/Platino-Palladiotype.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 · Jan 14, 2009

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 · Jan 14, 2009

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 · Jan 14, 2009

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

Dan Dozer · Jan 14, 2009

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 · Jan 15, 2009

Dan,

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

Thanks!

dpurdy · Jan 15, 2009

It is called a hygrometer.

Dana Sullivan · Jan 21, 2009

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

PVia · Jan 21, 2009

Dana...would the 10% oxalic solution be in lieu of pre-acidification of the paper?

Paul · Jan 21, 2009

Dana,

Thanks for that tip. That sounds like the simplest solution of all. Though it does raise the question of what steps need to be taken after coating and drying the paper. If one uses a hair dryer (as recommended) to dry the emulsion, does that not dehumidify the paper enough to cause problems?

Also, would you recommend acid soak even for papers that are not typically regarded as requiring it, such as Cranes Platinotype?

Thanks,
Paul

Blunt · Jan 22, 2009

Dana Sullivan said:
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

Circus Tricks! I resent that

Bill Blunt

Vaughn · Jan 22, 2009

Paul said:
...If one uses a hair dryer (as recommended) to dry the emulsion, does that not dehumidify the paper enough to cause problems?Paul

Is a hair drier still "recommended"? I use to use a hair drier (after waiting ten minutes or so to let it really sink in). But after getting asthma from the platinum dust the drier kicked up, I went to air drying (paper tacked to a wall with a fan blowing over the paper) -- and got better prints for it. I coat all the sheets I will be using that printing session, and once the prints are dry enough, I put them in a box to hold them until I need them. If your RH is very low, you can put them in a plastic bag to hold the moisture level.

Dana -- how does one determine "90% dry"?

Vaughn

Paul · Jan 23, 2009

From reading some of the previous posts it appears that many if not most people do not recommend drying with a hair dryer. I guess I was trying to be true to what Dick Arentz recommends in his book.

I think I will try what Dana recommends and coat the paper either with water or and oxalic acid solution, and once coated with sensitizer, will let the paper air dry. I will also try to crank up the rh in the corner of the basement in which I work with a humidifier.

Humidity control and Pt/Pd

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