My BC starts crusting before I can even finish frosting my cake & it's driving me nuts! I just recently started having this problem about a month ago. The only thing I have changed is measuring out my PS rather than using the 2 lb bag of C&H PS & I use less meringue powder now. I use the basic Wilton BC recipe with the exception of Hi-Ratio Shortening:

2 C Hi-Ratio
6-7 C PS
2 tsp vanilla
1-2 Tbsp meringue powder
6-8 Tbsp water depending on consistency

Anyone know the cause? Thanks for the help!

Crusting is a function of the fat to sugar ratio, not meringue powder. And your ratio actually looks right. 1 c fat to 1 pound sugar. Maybe I'm missing something . . .

With the hi-ratio it probably won't taste greasy. Its a different product than crisco.

I'm thinking the weather could very much have lots to do with it crusting so quickly. Have you tried other recipes? Here's a great one......http://cakecentral.com/recipe/2-icing

Thank you kakeladi for the recipe link. I do want my BC to crust, just not before I am done frosting my cake. I will try to decrease my PS & see if it makes a difference.