Daft person that I am, didn't sand down the silk walls before putting Matt over them.
First coat went on a dream, waited a few days, did second coat and bang, crazing appears within an hour 
.
What can I do now? It's not hugely noticeable but I can see it.
Wondered about putting a coat of something on (someone suggested zinsser) and then trying again?
Or do I just cut my losses and pay someone to come in and do it?
I was so pleased with it too! Grrr!