Ive been using a high humidity crusting buttercream. I smooth it out with hot water and the viva method and it's still lumpy underneath
I thought I wasn't using enough icing so I used a little more next time around. Must've been too much cuz then I got ripples
I also had issues with icing blowouts. Most of my cakes were iced in buttercream and it seems like it's only a problem in the warmer months. I tried everything.. cake spackle, weighing the cakes down after filling them, changing the icing recipe and the list goes on. Finally someone suggested I only ice the cakes at room temp which includes the crumb coat. Once I did I haven't had problems with cake farts since!! I've been doing more and more fondant covered cakes recently, and was extra worried about bubbles under my fondant! No problems so far, fingers crossed. oh the trials of a caker!!