I am making dd a muppet cake. I've made the muppets out of fondant icing but I think their hair will look best a bit stiffer so I want to use royal. I need to make tiny amounts of several colours. What's the best way to avoid it hardening while I'm fannying mixing colours? Tried to get Betty Crocker so I could microwave each time to loosen it but have tried 3 supermarkets to no avail. Do you reckon I can microwave home made royal icing?