If you've ever seen a white-ish color coating on chocolate, then you have a good idea of what frosting looks like.
It is a byproduct of a natural wax and in no way affects the burn ability or fragrance of your product. It is caused by tiny crystal growth that forms on the top and sides of the wax. Frosting is a perfectly normal and an effect of using natural waxes and is also unique to vegetable waxes. It is the natural wax trying to return to its natural state.  All natural waxes frost and is a sign that your products are made from a wax that is 100% natural.
Some waxes have additives to stop this frosting however if you want a 100% natural product then you can expect frosting.
Frosting does not affect the performance of your candle or wax melt and is something that you shouldn’t worry about as you still have a high quality product that will deliver a beautiful scent.