Sometimes the galvanising process leaves an excess of zinc on the wire. Budgies can chew the wire and end up with heavy metal deposits in their system which will kill them.
That is a pretty painful way of dying!
If you use galvanised mesh of any type, it is best to wash it down with vinegar. This is a dilute acid. Also make sure there are no pieces of zinc hanging on the wire that the bird can break off and digest.
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