Condensation on cakes, also known as cake sweat, is one of the most frustrating parts of cake decorating. I’m going to show you two reasons why condensation happens, two ways to prevent it, and how to fix it.
Condensation is not pretty. You've probably seen it in the form of ugly droplets on the sides of a cake. Even worse, it can make coloured decorations run and also cause pools of coloured liquid on the cake board.
Why does condensation happen?
The first reason is a change or difference in temperature. This happens when the temperature of the cake within the frosting is colder than the air outside the frosting. Condensation (or cake sweat) will happen with any big change in temperature. For example, moving a cake or cake layers from the fridge or freezer to a warm room.
I always recommend chilling cake layers before frosting because they get firmer and less crumbly. This means your cake won’t wobble on the turntable as you spread the frosting on and while you smooth it. But if it’s hot in the room, after about 15 minutes you’ll see droplets of condensation forming on the frosting.
Let’s talk about the other reason condensation happens: moisture in the air. As I mentioned, I’m a big fan of chilling cakes before frosting them and also after decorating. This keeps the frosting and decorations stable and makes cakes more stable for transporting, too. I also love being able to freeze cakes so that I can make them in advance for an event or occasion. This gives me the flexibility I need since I have three little ones.
The challenge with fridges and freezers is that there’s a lot of moisture in that cold air inside them. This is caused in part by opening and closing the fridge or freezer door, which lets warm air in.
So, condensation is caused by: 1) differences in temperature of the cake and the air around it 2) moisture within a fridge or freezer.
How to avoid condensation on cakes
Good news! You can avoid both of those types of condensation.
First, minimize changes in temperature. So if you chill your cake layers, frost them in a cool room. If you freeze an entire cake, put it in the fridge for 24 hours to defrost before moving it to a cool room.
The second way to avoid condensation on cakes is to wrap cakes in plastic before chilling in the fridge or freezer. If you put a cake in the fridge or freezer for an hour it won’t pick up any moisture. But it you’re leaving it there for several hours you'll need to protect it from moisture. Use two layers of plastic wrap so that the cake is sealed and protected.
Yes, these are buttercream cakes! If you’re wondering how to wrap them without damaging the frosting, here’s the trick. After frosting the cake, put it in the freezer for an hour. An hour isn’t long enough to develop condensation from the moisture in the freezer but it is long enough to set the frosting. Once the frosting is cold and firm, take the cake out and wrap it in plastic. The frosting will hold its shape even when plastic wrap brushes against it or rests on it.
When the cake goes back into the fridge or freezer it will be sealed and protected from any moisture. When you take the cake out of the fridge, unwrap it before the frosting on the cake warms up and softens. This way the plastic wrap won't damage it.
How can you prevent condensation if the cake is being served outside?
Ideally, the cake will be at room temperature and the temperature outside will be the same as the temperature inside, but that’s hardly ever the case.
Take the cake outside at the last possible moment and find a spot for it in the shade. If possible, position a fan to blow onto it. These will all limit the amount of condensation caused by the change in temperature.
How to fix condensation on cakes
Sometimes it's not possible to avoid condensation on cakes. If you live somewhere hot and don’t have air conditioning you'll experience it if you chill cakes between decorating steps. If you forget to wrap a cake in plastic before chilling it you'll also notice condensation droplets. Don't panic! It's possible to remove condensation from cakes.
After a cake comes out of the fridge it will take a few minutes before condensation droplets start to appear. The hotter the room, the sooner you’ll see the droplets. Take a paper towel and gently press it against the cake and it will absorb the condensation.
This works because my 4 Minute Buttercream frosting sets in the fridge, meaning it gets firm. Once this happens you won’t indent it or leave texture or pull it away with your paper towel. You might have to dab the cake a few different times while you’re decorating as the temperature of the cake slowly warms up to match the temperature of the room.