I have many recipes that require mixing brandy into melted chocolate. I find, in every case, that the chocolate seizes and I have chocolate shards instead of a smooth mass. What am I doing wrong?
My guess is that you're adding the brandy cold, and the chocolate may also only be partially melted. Try:
Ensuring that the chocolate is thoroughly melted;
Heating the brandy first (to just below boiling);
Gradually adding the chocolate to the brandy (not vice versa). Chocolate seizes the worst with small amounts of liquid, so you're doing the opposite, adding a tiny amount of chocolate at a time to a relatively large amount of liquid).
I agree with Aaronut's answer. Another reason you may be having problems with chocolate seizing is that you aren't adding enough liquid. Are you trying to "go easy" on the brandy and use less than your recipe calls for? If so, that is most likely the problem. A little liquid will cause the chocolate to seize, but a lot will not.
Here's an example that will demonstrate what I am trying to say. Think of a bowl of sugar. If you put a few drops of water into it, you will get little hard clumps. If you add a lot of water, you will not get those clumps, and you will have a liquid.
I don't know the exact liquid to chocolate ratio off the top of my head, but a matter of a tablespoon could prove to make a big difference in having a smooth or seized chocolate.
Are you then adding the mixture to anything? I have just made a "mousse" of whipped cream and melted chocolate, and wanted to add some grand marnier. The first attempt seized, and I just whipped it into the cream as a lump, and it came out fine (with a few tiny solid bits). 2nd batch, I added the melted chocolate to the whipped cream and then added the grand marnier and voila! It was perfect.
Yes, when you add water to melted chocolate, it seizes. It's like sugar. If you add just a little bit of water to sugar, it will form clumps as the particles stick together. If you add enough though, it'll turn smooth again. Chocolate particles behave the same way. Try it with some cocoa powder. The same thing is happening, except inside the suspension/emulsion of cocoa butter and chocolate particles.
To avoid this problem, melt your chocolate with the brandy.
Aaronaut's solutions may be correct, at least the last one I can say is. I don't see why heating the brandy would help, the particles would still behave the same. Seizing has more to do with the ratio of water/chocolate particles.