Hi! I know I read a post on here somewhere about buttercream icing getting air bubbles? It happened to me yesterday for the first time and although I could remember what to do (small pin hole, press out air) I couldn't remember what the post said about why it happens? Thanks for any info, i don't want that to happen again!

I think the biggest consensus is that it happens when the cake isn't allowed enough settling time. I think it might have to do with temperature/humidity changes as well.

the pin holes is for bubbles in fondant. If you are getting air bubbles in buttercream you are mixing to long perhaps.

Most likely airbubbles in b'creamed cakes is caused by not pressing the icing 'tight' enough onto the cake. It usually happens on smaller/6"er cakes. There is something that causes 'gas' to form in any voild so pressing a bit harder to adhere the icing well to the cake should help.
I like the suggestion re-posted about sliding the spatula under the bottom edge. It can be covered with the bottom border later.

Yes, make sure you press the buttercream to the sides. I've had good luck with a very thin crumb coat first, then while it is still dry (not crusted) putting the top layer on.

THanks everyone! I've done several cakes and I've never had this happen before! I know that you can use a pin with fondant but when you've got a cake, at the venue, already assembled and decorated the pin hole trick works too. Thanks again everyone!