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10 Rainbow Cake Hacks

Use these 10 rainbow cake hacks for techniques and designs to make your rainbow cakes quick, easy, and better!

#1 Mixing rainbow colours in one bowl

Let's start with how to mix rainbow colors in just one bowl. Start with yellow and then continue in this order:

make rainbow colours in this order

This is not the order of the colours in the rainbow! The reason for this order is that the leftovers of each colour in the bowl can blend together with the next colour without muddying or dulling that colour. For example, leftover orange mixes into red and then leftover red mixes into purple. You can add more plain white buttercream to the bowl as needed but you won't have to clean the bowl.

mix rainbow colours in one bowl

Even without washing the bowl in between, you'll end up with gorgeous, bright rainbow colours.

#2 Mixing rainbow colours in a cupcake pan

To mix small amounts of rainbow colours (which I'll show you how to use later) use a cupcake pan. It's more convenient than using lots of little bowls because it's quicker to wash up afterwards.

mix colours for a rainbow cake in a cupcake pan

Also, you can tint the colours in advance and cover the whole cupcake pan with cling film or Saran Wrap. This keeps the buttercream soft until you use it so that it doesn't dry out and crust.

#3 Piping rainbows

To pipe rainbows onto your cake, line up your coloured frosting on a piece of cling film or Saran Wrap. Then roll it tightly into a log.

rainbow colours on saran wrap for piping onto a rainbow cake
plastic wrap log for rainbow colours

Cut off one end and drop that end down into a piping bag. Use a star tip to pipe arcs onto your cake and all of the colours of the rainbow will come through.

how to pipe rainbows onto a cake

Add clouds by piping white buttercream at each end. If you're using a small round piping tip like this #4, squeeze each dot for a few seconds. This allows it to bulge out to make these fluffy clouds.

piping a rainbow cake

#4 Making a flat rainbow on a cake

For the quickest rainbows, squeeze blobs of rainbow colours along the straight edge of a cake comb. Rest it against a frosted cake and curve it around to spread the frosting onto the cake into a rainbow.

how to spread colours to make a rainbow on a cake

You might need to scrape a few times to get the frosting really smooth. You can carve shapes or letters into the rainbow using a petal piping tip.

use a cake comb to make a rainbow cake
how to carve buttercream with a piping tip

#5 Stencilled rainbow cake

To create a stencilled rainbow you only need tiny amounts of rainbow frosting. Attach your stencil to a chilled cake by taping it tightly or pinning it into the cake. Spread your rainbow frosting over the stencil one colour after another.

how to make a rainbow stencil on a cake

When you scrape over this with a cake comb or spatula you'll take off the excess and blend the colours together naturally. Peel the stencil off to leave a stunning rainbow design on your cake!

stenciled rainbow cake

#6 Layered rainbow cake

Another quick way to add rainbow colours to a cake is with this layered technique. Frost and chill your cake first so that the frosting is very firm. Then pipe or spread your first colour around the cake. Since the frosted cake is cold and firm, this colour won't blend into it. Scrape around the cake with a cake comb to flatten and smooth this colour.

how to layer rainbow frosting on a cake

Now pipe or spread your next colour above or below the first colour. If your cake isn't very cold you'll need to chill it in the freezer for about 2 minutes in between each colour.

layered rainbow cake

These layers of rainbow colours are simple but the result is beautiful!

#7 Shaped rainbow cake

To make a cake in the shape of a rainbow is super easy. Cut round cakes in half and layer them with filling.

how to make a rainbow cake stand up
how to make a rainbow shaped cake

Then flip the cake onto its side and you have a semicircle or a rainbow shape.

how to make a rainbow cake with round cake layers

Frost the cake to seal in the moisture so it doesn't dry out. Then cover it with rainbow piping or however else you want to decorate it. You can read or watch my detailed tutorial on how to make this rainbow cake.

how to pipe a rainbow cake

#8 Piping onto a rainbow cake without couplers

To pipe with rainbow colours using just one piping tip for all of your colours, use this hack. Prepare your colours in piping bags with the ends cut off each one, but without piping tips in the bags. Choose your piping tip and drop it into a different piping bag. I'm using an open star tip #32.

rainbow cake hack for couplers

Drop your first bag of coloured buttercream into the piping bag with the piping tip. You'll squeeze this colour out through the piping tip of the other bag. When you finish, pull this piping bag of coloured frosting out of the piping bag with the piping tip.

how to use different colours with one piping tip

Drop the next colour in and squeeze out the last of the previous colour into a bowl until you see the new colour come out.

how to use piping bags without couplers for a rainbow cake

Pipe with this colour and repeat for the rest of your colours. Always squeeze the bag into a bowl in between colours. With this hack you can pipe colourful designs without needing a piping tip for each piping bag of coloured frosting. The cake in the photo below was made using my facelift frosting technique:

rainbow cake with facelift frosting technique

#9 How to make rainbow cake layers

For rainbow coloured cake layers inside the cake, try this. Divide your batter and tint each bowl and then spoon each colour into a piping bag. Squeeze the bags into cake pans, making random colourful designs.

how to make rainbow cake batter

Tap the pans to level the cake layers and bake as normal. When you cut into the cake everyone will be surprised by the fun colours!

rainbow cake layers

#10 How to cover a cake with rainbow sprinkles

To cover a cake with rainbow sprinkles choose tiny non pareils or hundreds and thousands. Smooth the frosting on your cake but it doesn't have to be perfect for this design. Scoop up handfuls of sprinkles and press them against the cake while the frosting is still soft and sticky and they'll attach easily. It's best to put your cake on a tray to catch the sprinkles that bounce off.

how to cover a cake in sprinkles

This is a popular choice for a cakeover or a cake makeover, where you buy your favourite flavour of cake and redecorate it. You might do this to personalize it or just to save yourself the time of baking.

rainbow sprinkle cake

These tiny sprinkles create an instant rainbow effect without needing to master any cake decorating techniques. Since they're so tiny, they really don't add much texture to the cake when you bite into it.

Which rainbow cake hack will you use? Tell me in the comments! Visit my cake school to learn hundreds of cake decorating techniques and designs with my online courses and memberships. See you there!

You can also watch a video of this tutorial on 10 rainbow cake hacks:

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