Where I live, we don’t have Satin Ice nor Wilton, most professional baking stores carry Italian brands fondant and gum paste. They also have some other European brands but mainly Italian. I get the same problem you mentioned. The fondant rips on the edges. I live in a humid weather and I do use cornstarch (not powdered sugar). So is it the weather and not the brand? or the starch?
Dina @ miettes, http://www.facebook.com/pages/miettes/257790597632317
