Anyone have the same prob/might know the cause of the prob of cake tiers that develop HUGE air bubbles under the buttercream icing? I'vce had a few cakes do this recently. They're fine while being iced. Put them in fridge and when they start to warm up, they start to "grow a huge bubble under the buttercream, making it poof out. You can kinda pop the bubble, but then have to resmooth the icing. Just had a customer say it happened to her once she got home. Grrr..... I seem to notice it most on the red velvet cakes...
Some people say it is chilling the cake that causes this and I would like to agree except it does it on never chilled cake too. And if you're making a traditional red velvet you've likely got cream cheese filling and it needs to be kept chilled.
It's air or cake gas collecting & trying to escape.
Some people weight their cakes down before icing to in effect burb them.
Some people pin prick each layer of cake through the icing so the air has somewhere to escape.
I've heard that the weights work great. Pin pricking works great for some.
My theory is that its where you have not completely sealed the cake with icing...maybe there's a gap where the filling doesn't quite meet the icing dam, or maybe the cake was iced in a hurry to where air was trapped between the cake and the icing in a few spots.
The times I've noticed it happened to me, that's the conclusion I came to.
Yeah, it's just gas escaping, so you must have had a gap in the filling or in the icing between the layers. It's annoying but if you press down on the layers after filling the cake, then make sure that you're really pressing the icing into the space between the two layers and not leaving any space with air in it you can minimize the chances of it happening.