When I was in France last year, I watched coppersmiths tinning cooking
pots with zinc chloride flux and bar tin. They made it look easy (of
course they were pro's) and were doing it over a plain gas ring. Clean
the pan, flux the part you are tinning, resist the rest (they used a
chalk wash), then heat over the gas flame while rubbing with the bar
tin. When it starts to deposit, run it all over the pan, then take a
heavy cloth and wipe it around evenly. All done. Didn't take more
than a couple minutes per pan.

I suspect the end result improves dramatically with practice! :-)
These guys probably tin thousands of pots a year.

Regards,

Bob