I covered a fruit cake in marzipan icing and then in plastic icing and the plastic cracks. what can I do to prevent this?

Can you elaborate on what "plastic icing" is? I have never heard of this.

Thanks

Not sure how you refer to it in the UK. White fondant looking preprepared icing. just roll out and cover cake. does this help?

think you are meaning fondant (sugarpaste in the uk). make sure its kneaded properly, and you work quickly, so it cant dry out. be quick, but careful when moving it to the cake, you want to avoid stretching.
might help if you can post a good quality close up too.
xx

brincess, I have quite a few recipes for cake coverings. I think this particular mix will be the sugar paste. the fondant recipe I have gets gelatine in and is easier to work with. this paste gets dryer the longer you work with it and has cracked everytime I've used it so far, round or square. Small cracks on the folds. I also try not to roll it too thin

fondant and sugar paste are the same thing though, at least in the usa and the uk. might help if you post the recipe you use - or the brand name if you buy it. might just be this one doesnt work for you, yours climate etc better trying another one.
xx

plastic icing is called fondant in the US and sugarpaste in the UK.

Make sure you knead it well and roll out on some holsum, icing sugar (powered sugar in the US) or cornstarch (mazina) will dry the paste even more. Also make sure you roll it fast and then place it on the cake, if you leave it without covering it wil also dry out fast in this heat.

HTH!

THANKS Cakechick. I rolled it out on icing sugar. Now I know better.

Just be careful if you use cornstarch, it can react and cause bubbles under your fondant.
Maybe look at using vegetable fat, or a vinyl/ silicone mat.
xx