Made a chocolate glaze for a cake-- basically the Sacher glaze -- and it's a bit grainy. Here's what I did: 1 cup sugar, 1/2 cup water, 4 ounces good dark chocolate (70% Lindt). Bring to a boil in a small pan, lower the heat, and, stirring, bring to 234F. Stir to cool & thicken for one minute, then use immediately. I did all of this,and though it looks the biz -- lovely and shiny, and thickened right onto the cake -- it's a bit grainy.
What did I do wrong? I have an old style candy thermometer and I thought I got it to 234 (a bit hard to read, though), and I was careful not to scrape the pan as I was glazing. Too hot? Not hot enough? Took too long to heat? ( the recipe said it would take about 5 minutes to hit 234 -- it took more like 8)