Last night I got frustrated with my wet printing because the trays got cold and kept making muddy prints. This is almost summer here but the AC makes all the cold air come down to the basement where my darkroom is. I have decided to invest in something to keep my trays warm. Besides a small space heater, I am considering a heated, waterproof blanket of some sort to put under the 11x14 trays. Now, I am very aware of this great suggestion of the pig heater blanket in a APUG post: http://www.apug.org/forums/forum43/35600-sue-weeee-4.html This blanket seems nice but is pricey. As an alternative I came across these waterproof foot warmers on Amazon: http://www.amazon.com/Indus-Tool-FWB-16-by-36-Inch-Foot-Warmer-Mat/dp/B0013V1PYA/ref=sr_1_16?ie=UTF8&qid=1337792212&sr=8-16 These are waterproof, sealed and the right size for me. Additionally these are much more reasonably priced than the pig warmers. I was wondering if any one else is using these for keeping their trays warm in darkroom. Do you think I can use these with dimmer switches to adjust the temperature? I don't want to add complexity of a submersible heater or even a thermostat. But I do have a waterproof digital kitchen thermometer that I can use to check the tray temp. once in a while. Any other thoughts?