Hi I read this just today on one of the exisiting  answers (when to decorate). It is equal quantities of sugar and syrup boiled for one minute.  Vanilla or lemon or orange juice can be added for flavour e.g. for carrot cake.  Hope this answers the question.

Sugar syrup is equal parts of sugar and water e.g 200g sugar to 200ml water. Bring to boil for about 2 mins. Brush the cakes with it, leave to cool then freeze and it should keep them moist.

Sorry it was ’Timings for decorating’ page 2 or questions

thanks folks

I’ve never used sugar syrup, does it make much difference to the freshness. Does it work best with frozen cakes?

Sugar syrup drench gives the cake  moistness, adds extra flavour and can also helps extend cake life by a few days. It can be used when a cake is fresh or if it’s become a little dry, of course you can use it on a de frosted cake before filling and icing.  Have a look also at the question on’ timing before decorating’ for addition information.