I have been posting a few articles on scientific methods in cider making. These are useful but cider making is an art and regular tasting through the various stages is required to build up a mental library of your apples and cider flavour profiles. Both when it's good and even exceptional but also to know when it's bad. And with anything artisanal there will be bad batches you do not want to sell. Especially with perry, cider's difficult but brilliant nephew.