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.