I've always called soft solder the alloy that is used for electrical and
plumbing work, it has a melting range of 400 degrees F or so depending on
the ratio of the alloys components. Hard soldering uses silver solder (or
other alloys) with a melting range much higher, like 1250 degrees F or so,
again depending on the alloys component metals.

I recommend the book 'Soldering and Brazing' by Tubal Cain. It really does
a fine job explaining the why's and how's of what you are interested in.
The best help I got from the book was how to prepare the joints to be
soldered. He shows how to make an incredibly complex model, a boiler, using
13 different heats and several melting ranges of the silver solder.

Rosin core solder is intended for electrical work. You ought to get some
rosin flux (Radio Shack has this) and use this with your rosin core solder -
make sure that the parts are clean before you solder them. The 60/40 means
60%Tin and 40% Lead.

Roger

"mj" wrote in message
ups.com...
I'm doing some brass model building and the book that I am using as a
guide (by Gerald Wingrove) mentions hard and soft solder. What am I
looking for as far as differences? I suspect the "hard" solder has a
higher melting point (silver solder???) than the soft solder. The stuff
that I got at Radio Shack has this on the label:

Standard Rosin-Core Solder
60/40 (does this mean 60% lead/40% tin?)
.062 dia
8 oz.

I suppose that this is more a "soft" solder. What specs should I look
for in a "hard" solder.