All Occasion Cakes

Air Bubbles in Icing, No Thanks!

Has an air bubble ever popped up in your icing? Mine too. Air bubbles in icing when you are decorating a cake are frustrating and can ruin a beautiful job in a matter of minutes. They can show up immediately, slowly over time, or they can develop during delivery, but why do they show up and how do we prevent them? These are questions cake decorators have been asking for years. Today we’ll take a look at how to avoid air bubbles in icing.

Air Bubbles in Cake - How to Deal with Them!

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When an air bubble is formed, the buttercream actually pulls away from the side of the cake. Air bubbles can form before or after applying fondant. In the photo above, the large air pocket on the periodic table is due to the buttercream pulling away from the cake. Luckily, this was my son’s birthday cake, not a client’s, so no one cared about the bubble but me.

What causes air bubbles to form in icing? Here’s a look at some popular theories:

Decorated Cake with Air Bubbles

1. Settling

The most prominent theory is that the air pockets are formed due to settling stacking a cake. Although bulges can occur if your icing is too soft and it squishes out from between the layers due to settling, I have cut open a bubble to investigate and have found that the filling of buttercream between the cakes has not moved. I have also seen many air pockets that form that are not close to the layer of icing in the middle. There have also been reports of air pockets forming on Styrofoam dummies.

Using a thicker or more stable buttercream, such as Italian or  Swiss meringue buttercream, can help your cake hold its own weight with much less settling. If you love American buttercream, make sure your buttercream is thick but spreadable. This can help stabilize your cake and reduce settling.

Icing a Layered Chocolate Cake

2. Trapped Air

Another theory is that when stacking cakes, a pocket of air is trapped between the layer of filling and the cake, then due to the movement of picking it up, setting it down and spinning the cake, the air bubble slowly pushes its way out. It then reaches the edge and if you have already covered your cake in a beautiful thick layer of buttercream, the air pocket, pushes its way out to the buttercream and forms a large air bubble.


Baking Soda and Baking Powder

3. Leavening agents may be the culprit

If you make cakes from scratch, it is best to sift your leavening agents together with your flour to help disperse the ingredients throughout the mixture,allowing for better rising overall as well as reducing clumping. There are many decorators who believe that the air pockets are formed due to gasses that are released when baking soda or baking powder are not mixed properly and are left exposed to the buttercream or fruit fillings. This combination causes the formation of gases within the cake and air bubbles are formed. This theory could explain why air bubbles sometimes reappear after you have fixed them, but I cannot prove or disprove this theory since I am not a food chemist.
Iced Cake

4. Cooled or frozen cakes

Another popular theory is that air bubbles form due to the change in temperature when cooling your cakes in the refrigerator or freezing layers of cake before filling and stacking. The theory is that when they warm to room temperature, the bubbles form.

I believe I have personally debunked this. While making a three-tier wedding cake using American buttercream, I chilled the top and bottom tier but left the middle tier out to crust. Within the first hour, the room temperature cake had formed an air pocket near the base of the cake. The bottom tier, which was chilled overnight before being covered in fondant, never developed an air pocket. Also, after fixing the air pocket in the middle tier, I placed it in the fridge and chilled it overnight. Another air pocket never developed.


5. Fruit filling

There is a theory even taught in some cake decorating schools that filling a cake with acidic fruit filling, such as lemon curd, could be the culprit. Although some of the cakes I have had problems with do have this type of filling, I have made many cakes filled with lemon fillings that never developed air pockets or bubbles.
Mixing Buttercream

6. American buttercream vs. the world

Buttercream can be a controversial topic among cake decorators, so I won’t get into a discussion on which buttercream is better, however, in my experience I have not found an instance where air pockets have formed when decorating a cake with Swiss meringue, Italian or French buttercream. This seems to be a problem with only American buttercream, which consists of butter, shortening, powdered sugar and milk or cream.

Many cake decorators have also noted that when they make the change to a different buttercream, the air bubbles go away.

How do you avoid air bubbles in icing?

After researching this topic I have found a few ways that may help you avoid air pockets and bubbles to form in your cakes.

  • Many people advise poking your cake in unsuspecting places with a fine needle, this can give your cake a little breathing room.
  • Others say to place a vent hole in the top of the cake if you are stacking more layers on top or covering it in fondant.
  • Another solution is to run a thin spatula or a knife around the bottom of your beautifully finished buttercream cake to “break the seal” and leave an opening for the air to escape instead of creating bubbles.

How do you fix air bubbles?

  • If you happen to get a bubble or air pocket on your cake, it is a pretty easy fix if you have not yet covered your cake in fondant. Simply poke a small hole and gently press the air out until the buttercream adheres to the cake. If the bubble forms again, repeat the process.
  • Sometimes the buttercream will not go back into place or you may get a blowout where the bubble actually pops. If this happens, the buttercream will most likely need to be taken off and new buttercream will need to take its place.
  • If you have covered your cake in fondant and an air bubble develops, you can try to press it back into place but when the air pocket is formed it slowly stretches the fondant and then hardens. This can cause a large problem if you do not have decorations that can cover it. The fondant will most likely need to be taken off, the cake re-iced and covered in fondant again.

I wish I could give you a magic wand or even great advice on how to prevent and fix air bubbles in icing. The best advice I can give is to experiment with different types of buttercream. American buttercream is delicious, but the texture, ease of spreading and the stability of the European buttercreams may just change your mind and calm your nerves.

Have you experienced air bubbles in your icing? What type of buttercream were you using?

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Kenneth Reese

Thanks for the information! I just had this happen to me on my daughters cake and could not figure it out. Thanks again!


I have been using a thin layer of ganache to cover my cakes. There hasn’t been any sagging or air bubble problems since.

Elena Purton

What to use on vanilla cakes if people don’t want chocolate? Ganache is normally used for chocolate cakes, no problem but for vanilla etc?

Ken's Oven

Great article and awesome timing! Has been a while since I cover a cake in American buttercream (I prefer Swiss Meringue Buttercream) and just this morning my carefully iced cake had an horrible bubble, after reading the article I do think is the type of buttercream.



I always use Swiss Meringue Buttercream to cover my cakes, and never had bubbles in the icing.
Here where I live (Italy) we do not use shortening, so maybe that’s really the culprit of bubbles forming!

Elena Purton

No, I’ve used just butter and still had bubbles form,
So have no idea as to the reason why? Maybe take ing to much time to cover the cake or handling it could be the culprit?


I have had bubbles form with both the American buttercream and Swiss Meringue


I also have had air bubbles in swiss and italian butter creams


I always use American Buttercream however, I don’t use shortening in mine and never had an air bubble to date.


What’s your recipe for buttercream without shortening ?

Elena Purton

I assume it’s all butter and icing?
I do use half and half as I call it, shortening and butter but find it just happens to some not all cakes? Very strange indeed!😕

Elena Purton

Well this was very helpful but I have had air pockets appear only after I’ve covered my cake in fondant, using the same buttercream I’ve always used, American buttercream and I find it only happens when it feels like it lol!
I’ve done 2 cakes in that last 2 weeks, 1 was perfect the other formed a air bubble?? All my cakes get fridged before icing and I can’t understand why it only happens to some of them and not all?
Nevertheless I will try and note what I’ve done and what I’ve used on each cake to see if there is any differences maybe in consistency, cooling time, time it takes to cover the cake etc, etc.
Thank you for the post it’s been most helpful.


I only get ‘cake farts’ as they are affectionately known.. after fondanting. Mostly it’s due to my own inability to ease out the air while applying the fondant. My response? I don’t use the stuff anymore. It tastes ghastly anyway so now I only use ganache and white modelling chocolate rolled out. Ok so it’s not pristine white but the flavour is SOOO superior I’ve had zero complaints. It colours well and once you get used to working with it and it’s idiosyncrasies- it’s excellent. I do exclusively gluten free cakage and it’s perfect for almost all of my recipes; I use SMBC for the rest.
My worst experience was a sponge Bob two tier which developed a cf the size of a football pitch (!). I had to cut off half the blue fondant. It looked eight months pregnant. Luckily (and skilfully…!) AFTER the great freak out – I managed to cover up the damage with Bob’s pineapple house and you’d never have known there was chocolate cake oozing a couple hours before…
Best of luck bakers! May your bubbles be very small and extinguishable.


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