Reading through the page on the Guild Wars 2 wiki regarding crafting experience it makes mention to a 'Critical Success':
A critical success in crafting can either grant an experience bonus or refund some of the materials used but does not add to the value or stats of the item crafted.
What exactly is a 'Critical Success', and how do you know when you have succeeded in such a way? I am presuming this is similar to Critical Chance but for crafting, although the article doesn't specify that...