Well...when I was 16 I did an apprenticeship in blacksmithing yet that was ...hum...40 years ago.
In the US you have one of the strongest blacksmith groups in the world, have look at this link: http://www.anvilfire.com/
I wish we had anything close to that here in Australia.
A couple of email to the "guru" will set you on the right path to a knowledgeable blacksmith in your region, versed in the art of forging and welding a simple chain link with the appropriate steel.
"Hot dip" galvanizing is a very simple process yet not very healthy to do without proper ventilation. Many blacksmith have died from inhalation of zinc vapors by putting galvanized water pipes on the forge. Ask the blacksmith about it or take your chain to a galvanoplasty workshop. I must qualify what I am saying since I have no idea of the economics of this proposed solution. It is perhaps much more practical to just buy a longer chain, I don't know. However to link a chain is a job done in first year apprenticeship.
Spray paint galvo will rub off with use for sure. You can have the link forged in stainless steel 316, after all the amount of material needed is insignificant.
-- Edited by Marc1 at 03:28, 2008-03-23