I've been trying to frost a perfect crusting buttercream cake but have been having problems....

I crumb coat my cake first and let it settle over night and get it out the next day and frost it with my crusting buttercream recipe (the recipe has worked on cupcakes at room temperature) - when I do this, my cake start sweating and my buttercream just does not crust - so I cannot do the viva towel method or the roller method...

I've also tried to frost a crumb coated cake at room temperature - that did not go so well either! The cake is so soft, if I apply slightly more force to it - It just starts taking bits of the cake away (I live in somewhere really hot & humid) and it's just very hard to work with!

I don't think it's my buttercream recipe as I've got it working on a cupcake (here's the recipe I use:

1/2 cup solid vegetable shortening
1/2 cup (1 stick) butter softened
1 teaspoon clear vanilla extract
Easy-Add clear vanilla extractAdd to shopping list clear vanilla extract
4 cups (approx. 1 lb.) confectioners' sugar sifted
2 tablespoons milk
2 tablespoons cornstarch

So I was wondering - how do you frost your cake to get a perfectly smooth crusting buttercream cake?

Thanks!

I crumb coat my cakes at room temperature although I have had similar problems to you. Any soft cake will pull away and break off especially at corners when crumb coating. This is why I have opted to use more dense cakes and pound cakes over soft cakes. My red velvet and chocolate cake give me this trouble all the time but I use methods similar to the upside down method of icing to cover up any edges of cake that have come off.

I usually ice mine at room temperature. I use IMBC and a very lightly crusting American-style buttercream because a lot of people where I live just don't like IMBC. For any crusting recipe, I recommend you ice the cake at room temperature and then refrigerate it. Do you find you have to use a lot of pressure to spread the buttercream? If so, then your icing is too thick and that will definitely pull crumbs into the icing. You should thin it out with whatever your liquid of choice is, then do a crumb coat. Once that sets up then put a very thick layer of buttercream on. Use a bench scraper and go around the cake until it's smooth. Don't dig into the crumb coat. It takes a bit of practice but I can ice cakes in under five minutes. I don't mess around with foam rollers or paper towels or any of those shenanigans. Getting the cake smooth is about taking off excess instead of adding more.

Have always iced cakes at room temp and don't have the problems you mention.
Why are you putting your crumb-coated cake in the firg? It it *totally* UNnecessary. Once crumb coated they can & should stay at room temp. unless the filling must be refrigerated.

I put the crumb coated cake in the fridge because they are so soft that it's hard to frost.

I will give it a go at room temperature and see what happens! thanks everyone~

You say the cake is "too soft" at room temp. Maybe you need to make your icing softer. I never tried that recipe so can't say for sure but maybe you could try adding another tablespoon milk to soften it a bit for icing your cakes.