Hi 

I made corn syrup for the first time a few days back. I used cream of tartar and also covered the bowl with a lid for 2-3 minutes as suggested in the recipe, to avoid crystallisation. It seemed perfect, but when I took it out today for using in a recipe it was all crystallised. What could be the reason and how can I avoid it? My cream of Tartar packet has an expiry date of 10 Oct 2017. So it should still work ...right?