LONG PERIOD TEMPERING
Crystal clear blocks if boxed can go from standard freezing temperatures of -10 to 20 degrees F into the mid- to upper 30’s of a walk-in refrigerator for 8 to 12 hours or for overnight. Your block will be perfectly tempered in this period with little or no loss of water. If you have unboxed clear blocks, place the block on a small pallet with a heavy garbage bag over it and reduce the tempering time by a couple of hours. Even if you don't get to it right away in this environment, you'll just lose a little water. Non-clear blocks (notable because of feathering in the middle) are produced differently but can be handled in the same fashion as detailed above, but you should slightly reduce the time frames because they tend to temper faster.
QUICK TEMPERING
This can be done indoors over a floor drain or outdoors on the dock. It is recommended that you temper even your boxed blocks on a pallet in this process to help prevent leaning from occurring. If your block is not boxed you should garbage bag it before removing it from your freezer. I also recommend on unboxed blocks that you throw a moving blanket over it. This will slow the thaw to help give it a more even temper. Depending upon your freezer temperature and the temperature of the area you’re tempering your block in, the process will normally take between two to three hours. Three basic stages occur during the tempering process: the block comes out of the freezer clear to opaque; the block frosts over; the block becomes clear and wet. Once the block is clear and wet it is usually safe to carve.
CLEANING THE SCULPTURE
After you have completed carving your sculpture in the tempered state you can rinse it with a high pressure hose or even flash it with a propane torch to clean it up and make it clear with little or no danger of thermal shock. It is important to note that there is almost no chance of thermal shock during the carving or cleaning process if you use the long period tempering technique. In the freezer the abovementioned cleaning processes are not possible because of thermal shock. Therefore your best cleaning is by brush because it is highly effective since the sculpture in the frozen state is not wet.
STORING YOUR SCULPTURE
When storing your sculpture after carving it in the tempered state you again run the risk of thermal shock. This is especially true in very low temperature freezers. To prevent this from occurring you should insulate the sculpture with a heavy garbage bag, and if you do have a low temperature freezer you should also wrap the sculpture with a moving blanket. Never wrap the sculpture directly with the blanket without first plastic bagging it or the blanket's fabric will freeze to your sculpture. When placing your tempered sculpture in the freezer always place them on a pallet or you may run the risk of them freezing to your freezer floor.