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How to stop the cake from having the cake bulge when covered in sugar paste? I have covered the cake in buttercream 80g butter, 250g icing sugar and 25ml milk and a few drops of vanilla. I have built a dam woyhin the layers with the buttercream to seal the filling. Do I need to use a different buttercream mixture to make the buttercream more stable? Many thanks

Hi Maria44

It’s possible the buttercream with which you are crumbcoating is too soft. I would suggest making 250g butter to 500g icing sugar, no milk for the crumb coat and make a softer filling. Alternatively you could use royal icing, icing sugar which has egg white powder mixed in it. This will give a more stable crumbcoat.
The royal icing, icing sugar is found in the same aisle as normal icing sugar and comes with blue marking on the packet.