
You go to the hardware store and there is the bolt you need - zinc plated or galvanized - which should you purchase.
Zinc is pretty and shiny - galvanized is dull and ugly. But wait, if you're using the bolt outdoors, in a few years that shinny zinc bolt will be ugly rusted and that dull zinc bolt will still look new.
Outdoors, and where you need corrosion protection - Galvanized
Indoors, or in dry climates where corrosion is not a concern - Zinc

What is the difference between zinc and galvanized? Both zinc plating and galvanizing applies a zinc plating. So they both use zinc. The big difference is in thickness, zinc plating is typically 3 microns thick. Hot dip galvanizing is 50 microns thick - so you get 10 times the protection with galvanizing.
Even after 20 years outdoors this galvanized fence shows no signs of rust. The Galvanizing has formed a white protective coating (patina) that adds to its protective properties.
All true galvanizing is hot dip galvanizing. The term "hot dip galvanizing" is used so there is no confusion over some paint companies who try to full the consumer by calling their product "galvanizing". Parts to be galvanized are submerged in molten liquid zinc, hence the name "hot dip."....
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