Have you ever had that moment when you are melting your chocolate and it suddenly hardens up? What do you do? Likely, you try to add some liquid and hope for the best. But, you discover your chocolate has become solid as a rock and won't do anything.
Well, this is called seizing. And, yes, it's fatal.
The likely cause of seizing is water or steam getting into your chocolate. Sometimes as little as a drop of water can seize a whole bowl. So, that leads me to the next question: How can you avoid this?
Well, the first step is to make sure everything is dry: the bowl, the spoon and the molds. Next you need to check your cooking method. If you are using a double boiler, you should make sure the water never touches the bowl. And, you should keep the bowl over the water as the steam can escape and causing condensation to enter the bowl, thus seizing the chocolate. You should also never let the water boil because the splattering water will get into the chocolate. A low simmer is best. On final tip, do not let the spoon rest in the bowl. The handle may build condensation from the steam causing drops of water to slide down and get into the chocolate.
A better option for melting chocolate is in the microwave. The key to melting in the microwave is low and slow. Start by putting your microwave safe bowl of chocolate in the microwave. Set your microwave for one minute at 1/2 power or power level 5. When done, take it out and stir it, place back in. Repeat this every 30 seconds until almost completely melted. When small pieces of chocolate remain, stir until completely melted. If you put it back in at this point, you will likely get your chocolate too hot.
If you do get the chocolate too hot, just add some additional chocolate and stir. This is called tempering. It's difficult to get chocolate just right, but it's better to not overheat it. When I hand temper, I add chocolate and keep stirring until the chocolate has stopped melting. You can then remove the chunks of chocolate and begin using it. If your chocolate begins to dry and is shinny, you have it right. If it turns white, it's still too hot, continue with the tempering method.
Hope this helps!