A friend (and very good grower) uses that CLR cleaner stuff. I suspect
the "Lime-Away" brand would work just as well. I used to use acetic acid
at about 10% concentration. I don't know how this would work on thin
leaved orchids...

Hmm. I don't have any CLR around, but I just checked the bottle of
"Lime-Away". It contains sulfamic acid. Other rust products contain oxalic
acid, which is pretty strong. Does he dilute the CLR? Just curious.

Diana