Sn is tin.
The 30/70 tin/lead solder works fine in my experience.
I used it a few times as I didn't have any 50/50 around.
It melts at 361°F , Working temp - 491°(flow temp?) according to a couple sources that sell the stuff.
Looks like it was a favorite dent filler in the days of repairing sheet metal like car fender dents.
Rosin flux works with it and some of the solder offered is Rosin Core.
I've always just used a simple paste flux available in most DIY stores for any soft solder jobs. They usually have some Zinc Chloride in them,,the dreaded 'Acid Soldering Flux'
I tin the surfaces with it and also solder them together.
A very thorough rinse/neutralizing wash is used and I've never had any after rust issues.
