I know this has been covered many times over but can anyone shed some light on why these bubbles form in the icing. I have heard it is because of a moisture problem so I let my cake sit, unwrapped, for at least a half hour before icing it. Still got a big bubble after I iced decoated the whole cake and it sat overnight. I'm losing my confidence here!

Don't know why, but the FNCC tip of the week a couple of weeks ago discussed the solution.

From the 6.17.11 FNCC -

"OK, first tip of the night:

I learned this in culinary school and had promptly forgotten it. It has to do with those bubbles we all get on cakes. Three weeks ago, every wedding cake I delivered had a bubble. Then it hit me. When my Chef Instructor showed us how to ice a cake, the last step after smoothing the icing on the tier, was to run the edge of the spatula between the cardboard and the cake, "Breaking the seal."

Yes, it will mess up the very bottom of the tier, but that can be repaired later. Just let the cake breathe a bit (even a hour or two) and when you finish assembly with a ribbon or an icing bead the messy part will get hidden. If you're doing a no border of any type cake, then you'll have to repair the lower edge - but you won't be getting bubbles on the side of the cake that have to be repaired.

Once I remember this step, I've had no more bubbles."

We had a report during last night's FNCC that it worked for them also.

It could be that your cake needs some more time to settle, you put the icing on, then the cake settles a bit underneath the icing, and the icing bulges out from the cake as a result. Your work is gorgeous by the way!

bulges and bubbles/blowouts are different and have different solutions.

Thanks so much for the tip, Leah. And thanks for the compliment FullHouse And just for clarification, I'm talking about the big air bubble you get under the icing. I use a really stiff dam and let my cakes sit overnight after I fill them and that has taken care of the bulge problem. Unfortunately I haven't been able to figure out the air bubble problem. It is so disheartening to have a perfectly smooth cake, all decorated, and wake up the next day to a big bubble with the icing cracked all around it.

What I do, specially for tier cakes, is make a hole with a skewer at the top of the
cake so the air can escape.
Edna

It's not a moisture problem, it's just air escaping from the inside of the cake. Press down really hard (not hard enough to crush the cake, obviously) when you put the layers together and that will help force any air pockets out.

I actually got all excited when this happened to me recently because it meant that I could blog about it

http://acaketorememberva.blogspot.com/2011/06/dreaded-cake-tumor.html

Thanks for your reply costumeczar. I read the blog post and it was helpful. I'm going to try the tips you described

Costumeczar thanks for the informative article on icing blow outs! I find this happening more and more lately, so frustating! Now I know better how to deal with it.

with some cakes if its too warm or too chilled when the icing goes on this can cause what i like to say "its own weather system" lol.. the differences in the temps can cause that air bubble to occur. i just use a pin/needle for both buttercream and fondant bubbles - prick a hole then gently smooth it down. if your buttercream has crusted too much this may cause a blemish but most times is correctable at that stage- if the bc hasn't crusted be sure to dip your finger/knife etc in some cornstarch first. most times any residual corn starch will be absorbed over time as the smoothing action disturbs the surface layer of the buttercream making a bit of the shortening soft again which absorbs that corn starch.. if not once crusted just use a soft brush to brush it away.

my apologies. i got so in to writing my post i'd forgotten the subject was blow outs, not bubbles. carry on *smiles*

In my classes I teach to put a thin skewer down the center of the cake, all the way to the board, to create a "chimney" of sorts to allow expanding air to escape. I showed it in a Fondant 2 class one time, and the bubbles just sucked back in to the cake, and she laughed out loud with delight!