Silver solder

[Russmith007]

I have some used silver solder, and was wondering what percentage silver it contains? Also, what other metals are in the mix?

Thanks in advance for your answers.

 

[Harold_V]

There are various alloys of silver solder, so a ready answer may not be possible.

Some solders are low in silver, maximum of only 6%. Such solders are known as "soft solders" and may not be worth the trouble to process because the balance is often tin, which complicates recovery. These solders are generally silvery white in color.

If the solder you have has a light yellow color, it is likely high temperature silver solder. Content varies, but you can expect something like 45% silver, along with copper. Some of it contains cadmium, which is toxic. Avoid fumes if you do any melting.

There are many other alloys that you may encounter. It would be difficult to provide an answer without knowing which solder you have in your possession.

Harold

 

[Russmith007]

Thanks for your reply! This was the (relatively) inexpensive stuff from Lowe's, so it is probably low Ag content. We were doing some copper air lines, and I collected several handfuls of the excess.

 

[Harold_V]

Right now I'm in the middle of using the same, or similar, solder. I'm building a control panel for hydronic heating for our new home.

I'm saving any large pieces of solder that I can, but only to be added to my supply of copper and copper alloys for future use in my humble foundry. The solder, to me, has far more value for the tin than silver.

What you have would not be fun to refine-----it is likely more than 90% tin.

Harold

 

[goldsilverpro]

It is probably possible to dissolve and replate the tin electrolytically, leaving the silver behind as a sludge. I'll look through my plating books for a solution that might work. What is in the solder besides Ag and Sn?

 

[Harold_V]

That's a nice thought, Chris.

I can't speak for the solder in question, but the one I'm using is Harris Stay-Brite, comprised of 3.4/3.8% Ag, balance Sn. I expect others are similar, if not identical.

Harris Stay-Brite #8 contains 5.0/6.0% Ag, balance Sn.

Harold