Phals: do you cut back the part of the aerial roots that are dry?

[RosieC]

I agree, I cut back very wrinkled parts.

If they are firm but don't turn green with water then sometimes it's because that root is unused to absorbing a lot of water at once, I've seen healthy aerial roots where the water just rolls off them like a duck's back. Soaking the same bit of root for a while usually causes it to finally turn green though and turning green is a sign it's alive.