I'm somewhat of a newbie but have gained some experience. I've been using fondant (Wilton fondant ) for a while now when making cakes for friends and family and my wilton classes-- taste OK, looks great, but still one problem. Any cake I've made covered in fondant starts to starts to melt AFTER a few days. It looks just fine for about the first one to three days and then it gets very shiny, gooey, and sticky. If its colored fondant (red for example) the color blends into the cake! I store all my fondant cakes at room temperature because I know refrigeration messes up the finish. And during these winter times it's cold in the house. Does fondant normally do this after a few days or is something wrong? I want to get this clear before I attempt to start selling cakes in the future.
Well, even if it's cold in the house, it still may be humid--has it been rainy?
Any fondant, in a humid environment, will degrade--it's sugar. It's not "melting", it's liquifying in the presence of humidity. A sugar lollipop would do the same thing--try to go back to sugar syrup--because sugar attracts water.
If the cake under it is also moist, it's being assaulted on both fronts, too. If it's been covered in an airtight container, the process will be even faster.
I wouldn't expect any cakes that you choose to "sell" would be sitting around for "a few days", so it wouldn't likely be a problem.
Home refrigerators are very dry, so you can refrigerate a fondant covered cake. It'll sweat when the cold cakes comes into contact with warm, moist room air. If you don't touch it, it'll dry and be fine.
You can minimize this by boxing the cake, wrapping the box in saran, refrigerating, and keeping it wrapped that way until it comes back to room temp.
Not much you can do about the weather, though.