oh and one more interestesting fact. The first time this happened I read somewhere that I didn't have enough fat in my frosting, so I took my 50/50 butter and crisco recipe and made it 80/20 butter and crisco.... problem went from once in awhile to every single cake and happening hours after frosting. SO, it got worse. Now I'm using less butter...

I emailed edna and she says she sees it too.

If IndyDeb's is all crisco, and I believe the original recipe is, then it is not the butter. I got that on my first time using that recipe. It was a hot day in April and I was in a hot room taking a cake class. The bubble appeared while we were in class.

I still think it has something to do with the crusting of the icing. I only get it on icing that crusts. It is possible that the crusting is not allowing air or something escape out of the frosting. I never get this problem with SMBC, even with a shortening/butter combo.

Remember that shortening has something pumped into to help it get fluffy. I believe I read nitrogen? Could it be related to that?

And changing from a 50/50 butter and crisco to a 80/20 butter and crisco would actually mean you had a little less fat. Butter is 80% fat and 20% liquid and milk stuff. So if you wanted more fat you would be better off using more Crisco than butter. But I don't believe it is the butter/crisco combination given my experience with an all Crisco frosting.

I'm thinking it could also be a moisture thing. When I do get the bubble, it is usually one, not many. Could it be possible that it is a pocket of a dry area rather than too much moisture. And is it possible to get just one dry area? I don't know, I'm just thinking out loud. So maybe a light spritz of a simple syrup to make sure the moisture level is even so the frosting adheres could solve the problem.

simple syrup is a good idea! make it sticky! maybe the grand answer is that there isn't an answer!

Update: FYI I used to be a synthetic chemist...experiments are my nature!

Sooo...
50/50 butter crisco recipes...bubble
80/20 butter/crisco recipes...bubble worse
all crisco (indydeb's)...bubble.
cold cakes, room temp cakes, frozen cakes...bubble.

When it happens, its always on the cake itself not in the frosting layers where you would expect air to escape (and this happening on dummy cakes assures us that it is not settling).


What I have found is that it is surely a frosting adhearing issue, which some of us suspected. My frosting is cleanly just pulled away from the cake, just as clean as can be. As if it were never frosted.

Next experiment is a really stickly/loose crumb coat followed by another experiment with simple syrup...

I WILL figure this out!! So far the only thing I have found is that if I keep the cakes in the fridge the frosting is too hard to ever bubble. I just worry about what will happen when they go home!

I had this happen to me right before my very eyes! I have a light fixture right over my kitchen island where I usually decorate my cakes. I was using Wilton's BC recipe with half butter, half crisco. In October, it was a nice cool day. I noticed right where the cake was under the light it started to bulge because it was being heated by the light, it was about a foot away. I was working on a 4 tier cake, so it was quite tall. The bubble was about 3 inches wide. When I moved to the other end of my island away from the light fixture, the bubble slowly went away (I did poke it with a pin) and I had none return. Now I make sure I don't work directly under my light. I also think this could happen if a cake sits in a stream of direct sunlight (for example through a window while being transported in a car). Just a thought.

Interesting observations. I like all these results. And the one on a dummy is the best. Therefore it is not the cake or air escaping or temp of the cake.

Did you prep the cake dummy at all?
Did you try an all butter recipe?
Did all the frosting recipes crust?
Did you try with a noncrusting recipe? Not necessarily a SMBC or IMBC, but one that does not have more sugar than fat and will therefore not crust.
So if using it on a loose crumb coat (how do you do a loose crumb coat), maybe instead you can do the crumb coat, but you do not put it in the fridge, but rather let it dry out on the counter for 10 minutes. Or the crumb coat would not be a crusting recipe and the recipe would.

I never get this with SMBC, so I still think it is a crusting thing. I have just formulated a new non crusting chocolate recipe. I'll have to try frosting a cake with that and see what happens. So far I have used it on cupcakes.

Have tried the crusting buttercream crumb coat room temp, overnight, 10 min, and cold...all still bubble. not every time, but it has happened.

I don't know what SMBC is, but I didn't try all butter since it got worse when I increased butter and because I like a crusting buttercream for the smoothing effect.. then agian I don't know what the frosting is that you mention, can you smooth it too?

side note: We make huge batches of frosting, mixing by hand is not an option at all.

SMBC is Swiss Meringue Buttercream. It is an all butter, non crusting BC. The noncrusting part is why I think I personally have never experienced a bubble. Yes you can smooth it using the hot knife method.

Funny how we all like our different frostings. Personally I do not like a crusting buttercream. But that is because I like SMBC more. I certainly won't turn down a piece of cake that is frosted with a crusting BC!

I'll have to look up a recipe for that. can you get it as smooth as the crusted viva towel method. I won't stand for anything that is not as smooth as fondant.

Do you keep your cakes cold? I kept all mine in the fridge this weekend and didn't have a single issue.

Gorgeously smooth, I am a perfectionist

I keep it chilled till completely frosted. Once it is complete, it stays out of the cooler. This is at home. At my store I will probably chill till picked up.

do you mind sharing your recipe? I never saw this at home (how I started) or in my shop until early spring.... wondering is humidity has something to do with it?

Are you talking about SMBC? You can find it here on CC or if you google it. It is a pretty common recipe.

ok, didn't know if yours was special. I'll give it a shot. thanks!

Well I hate to burst the bubble, pun intended, but I use SMBC and I had one just Friday on the top tier of my wedding cake. After icing, refrigerated overnight. Stacked on Friday and decorated. Had to leave out on bench until hubby could come by shop and put back into fridge since it was too heavy for me to lift. The shop was a cool 65 degrees and it sit out for approx. 5 hours. Didn't notice the bubble/bulge on the top tier until he put it into the fridge. Looked like icing had pulled away from cake. Definately looked like an air pocket. I was able to fix but very annoying. I know the icing was secure to the cake when I iced it. It was in the upper 90's outside but very cool in the shop. I always deliver them right out of the fridge to the venue an hour so so before the event and check them over so now I'm wondering what happens to them after they sit for 5 or 6 hours after they thaw out? Hmmm

What is in your SMBC? Being in AL, I can only assume you do a butter/shortening combo.
If not then it is back to a humidity issue.

Also, once the frosting is on my cake, I do not refrigerate it. It could still be the cooling/warming up thing happening, if your SMBC has no combo stuff in it.

Okay, y'all cursed me! I'd never heard of or had a problem with cake farts until I read this thread earlier this week. Then, I had a four tier wedding cake due yesterday, and the top and bottom tiers both had "fart" bubbles in them. I finally had to cut two slits in the fondant where I was having the problems. Luckily, both bubbles were in the back, so it wasn't a total disaster. I kept thinking the filling was oozing out for some reason and that was what the problem was - until I remembered this thread. I don't know whether to scold you guys for giving me the curse, or thank you for giving me a heads up so I could figure out the problem!