On 06/10/17 12:10, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 12:25:31 UTC+2 schrieb David Billington:

Here is a venting guidance video from Wedge Galvanising
http://www.youtube.com/watch?v=C8EGUlerwVg , it include brief footage of
what can happen when an unvented items is dipped and it bursts.
By the way, I was told lately that galvanising sticks better if the steel surface is slightly corroded. Anyone know if this is true?

Possibly the corrosion leads to a rougher surface which results in a
thicker zinc coating. Items are intentional roughened by sand blasting
for that reason.