Keeping putty in the freezer retards the natural hardening process so if you find you are working on a piece and have to leave for any reason before you have a chance to finish you can put the piece in the freezer and it will keep it from drying for a short period of time ( I wouldn't push it past 24hours). When you come back to work on the piece just pop it out of the freezer and in a few minutes it will thaw and you can resume work.
Once putty is mixed it will "air" dry within roughly 20 minutes. Air drying does not mean that it is fully dry, in order to completely cure the putty needs to be "cooked" in a oven or type of kiln that we sculptor's refer to as "The Cooker". This precision engineered piece of equipment is an amazing amalgam of common household parts that can easily be assembled by even the most novice modeler. Here is my cooker:
I know.. I know.. your asking yourself "how can I ever obtain the parts for, let alone construct, such a wondrous device?" Well here's how:
"The Cooker" Parts List*
1. A large empty coffee tin (don't waste the coffee! Drink it!)
2. A simple desk lamp or heat lamp (these are larger and may be necessary for larger coffee tins, you want to be able to rest the lamp on top of the tin)
3. 1 50 watt bulb (DO NOT, I repeat DO NOT, use any higher wattage, it will melt your figure!)Once you have gathered your part simply cut open one side of the tin with tin shears or similar cutting devise (be very careful here we don't want any dismemberment) as shown.
That's it your done!
To dry putty in the cooker just place it inside for about 20 minutes and the putty should harden. Brown stuff will harden to the point where you can shave or sand it and green and procreate will fully cure so that when you touch the piece it won't warp or distort. I recommend cooking any project at each stage before going on to the next to ensure that you have a solid base to work on and you don't accidentally smudge something you just spent a half an hour sculpting (trust me I've learned this the hard way).
Hope you enjoyed the tips on putty, oh and yes the photo didn't make it past the sensor due to NDA reasons.