DS has chicken pox - has gone crusty in 3 days. Too soon to be un-contagious?

[WhenCanIWine]

Hes been really lucky - not ill, and not too many spots either. The advice is that once 'crusty' they are safe to take out again. But it seems a bit quick. What do you think?

sounds right to me, ds1 and ds2 only had a few spots and were definitely crusty by day 3. dd has now had it for 18 days, got it really badly, and still has a few that are only just crusting over...