Chocolate – Why would dipping a cold item in chocolate “help” with tempering

Your best bet is to start with a good quality tempered chocolate and melt it just to the point of melting, which is to say keep it 88° - 91°F (if you ever do end up getting a thermometer). Most suggest using a microwave for this in short bursts to keep the chocolate from getting too hot. If you use a double boiler, use a low heat and go slow. Pull the bowl off the heat often and stir. It may not seem like all the chocolate is going to melt, but keep stirring and add small amounts of heat. Or you can follow Alton Brown and sandwich a heating pad between two bowls and adjust the heat.

The theory behind this is there are 4 different types of crystals in chocolate. The good ones we want are Beta crystals, which do not melt until 91° - 94°F. As long as you don't melt the beta crystals, the chocolate should set back up to a proper temper.

Use a grater to make nice even bits, melt the chocolate 2/3 of the way and then remove from the heat. Stir off the heat until the rest melts, or add heat in very short bits, 5-10 seconds at a time. Don't let it harden either, it's harder to remelt if it's hardens up slighty as it then becomes one big solid mass to melt.

Once you break the temper, there is no going back, you have to start over and there is no real easy way to do that without years of experience as bobobobo said, or a thermometer. You can find inexpensive thermometers online, just have to make sure to get one that handles the lower range of temperatures. I use my chocolate thermometer to also measure the temperature of water when making bread. It seems more accurate at the lower temeratures.

Chocolate is an odd substance when it comes to melting and hardening. When chocolate hardens, its melting point will end up being just a few degrees higher than the hardening temperature.

When chocolate crystallizes at high temperatures, it forms a strong, dense crystalline structure that, texture-wise, is quite brittle. Most bought chocolate (baker's chocolate and chips) is already tempered, but when you melt it, you break down that crystalline structure, and if you harden it at room temperature then it ends up forming very weak crystals that will melt in your hand.

If you use a special coating chocolate (couverture or the lower-quality compound chocolate) then you don't need to worry so much about tempering (although it's still a good idea), but if you use ordinary chocolate and don't temper it then your coating will end up being messy and wet and rub off on your hands while you eat it. It might even melt while stored.

Tempering is the key to making a room-temperature-stable chocolate coating. If you don't do this, you'll need to keep your pastries refrigerated until they're ready to consume.