Before we look at how to crumb coat a cake, let me start by explaining what it actually is, and why we need to do it.
When I first started on my cake decorating journey, I remember hearing people talking about a ‘crumb coat’. But I wasn’t exactly sure what it was!
What is a crumb coat?
A crumb coat is a thin layer of frosting/icing, that seals in the cake crumbs.
You can either use buttercream or chocolate ganache to crumb coat your sponge cake.
Why do cakes need a crumb coat?
If you have ever tried to cover a sponge cake with a thick layer of icing, you will no doubt have noticed little crumbs of cake mixing in. These are transferred onto the icing from the surface of the sponge cake.
So, by doing an inital thinner ‘crumb coat’ of icing, these little crumbs of cake will be trapped in this first layer. Then when you apply your second, thicker layer of icing, it will be free from crumbs, giving you a much smoother, neater finish.
What icing do you use for crumb coating?
Most often, you will choose between buttercream or chocolate ganache for crumb coating a cake.
It can be down to personal preference, however there are occasions where one may be more suitable than the other.
Buttercream vs chocolate ganache
Using buttercream to crumb coat a cake
Buttercream can be great to start with if you are a beginner to cake decorating. It doesn’t set as quickly as chocolate ganache, so it gives you longer to work with it. This is perfect if you are working at a slower speed. Once you improve your technique, and can work more quickly, you will no doubt want to try chocolate ganache.
The downside to working with buttercream as a crumb coat, is when covering your cake with sugarpaste (fondant).
Buttercream softens at room temperature, which can make it more difficult to cover with sugar paste (fondant). You will not be able to press as firmly with your smoothers, so the finish may not be as good. Sometimes bubbles form as the cake settles, which can create air bubbles or ridges/ripples on your finished cake.
Using chocolate ganache to crumb coat a cake
Although it can be a little tricker to work with, it is worth perservering with chocolate ganache, as it will give you fabulous results.
A chocolate ganache crumb coat gives you a much firmer surface to work on. It makes creating smooth surfaces and sharp edges on your covered cakes much easier!
Is ganache better than buttercream?
Chocolate ganache is definitely my ‘go to’ choice when crumb coating all of my cakes.
During hot weather is when it certainly comes into its’ own. It will hold up under much higher temperatures than buttercream, making it perfect for summer wedding cakes, and countries with hotter climates.
As mentioned above, it can be a little more difficult to master than buttercream, both whilst making it and using it.
Chocolate ganache can split whilst making it, but just adding a few drops of boiled water from the kettle can quickly bring it back together.
You can also find it sets/dries quicker than buttercream whilst spreading it on your cake, so you do have to work a little quicker. It also depends on the conditions you are working in.
I would recommend trying out both buttercream and chocolate ganache, then decide which works best for you.
How long do you leave a crumb coat to set?
After your first initial ‘crumb coat’ you need to leave the buttercream or chcolate ganache to set before applying the next coat.
I tend to use 2-3 coats altogether, depending on how the second coat looks after applying. If I am happy with it, I stop at 2 coats, but if it is still not smooth enough, I will apply an additional thin layer to give the best possible finish.
How long this takes will depend on which you are using, as well as the temperature of your working area. In warmer temperatures, it will take a little longer to set.
Once you are able to touch the surface of the cake, without the buttercream or ganache sticking to your fingers, and if it feels firm to the touch, you can go on with your next coat.
Before covering with sugarpaste (fondant)
I prefer to leave my crumb coated cake overnight, at room temperature, before covering with sugarpaste (fondant). This ensures that it is completely set, and ready to cover.
If I am in a rush, I will cover aproximately 2-3 hours after the final coat, as long as it is firm.
Do you refrigerate after crumb coat?
I personally prefer not to refrigerate between crumb coats (or after).
If the cake is too cold (between layers), it will cause the next layer to set very quickly – perhaps even whilst applying, which can cause problems when trying to smooth it.
When it comes to covering with sugarpaste (fondant), a cold cake will develop condensation when warming back to room temperature. This causes the sugarpate to become tacky or sticky, making it difficult to work with.
If you feel you need to refigerate your cake whilst crumb coating (due to high temperatures), make sure to bring it back to room temperature before covering with sugarpaste (fondant).
How to crumb coat a cake (a step by step guide)
- Place first layer of sponge onto a thin cake card (the same size as the cake), securing with a little buttercream. Then add to a larger ‘working board’ – I use a large acrylic disc, but you can use a larger cake drum
- Fill with filling of your choice between each layer of sponge
- Trim the edges of your cake, to leave a small gap between the cake and the edge of the cake board
- Apply your first thin, crumb coat (buttercream or chocolate ganache), using an angled palette knife
- Allow to set
- Apply the second, thicker layer – use a scraper to remove any excess buttercream/ganache. Use the edge of the cake card as a guide (this is easier if you have a turntable too)
- Allow to set
- If you are happy with the finish, you can leave to set firm (preferably overnight – at room temperature) before covering with sugarpaste (fondant)
- If the finish is still not smooth, and you have gaps that need filling, apply a third, thin layer of buttercream/ganache. Smooth with a scaper until you have acheived a good finish.
- Leave to set (preferably overnight – at room temperature) before covering with sugarpaste (fondant)
How do you ganache a cake?
Watch my timelapse video below to see how I crumb coat my sponge cakes with chocolate ganache
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