Silver solder?

[vlmarshall]

Ah, lots of good info here! Mostly I'm posting so I can find this again in the far future, but I didn't realize how good I have it, to be able to use the silver solder and flux from work.

Speaking of work, stashed away in a drawer of 100lbs or so of silver solder sticks, both round and flat, is a bundle of very copper-colored sticks, which even the oldest employees there can't identify. Any ideas?

 

[Stan]

As someone mentioned, in North America, silver solder usually comes in coiled wire form, ribbon or sheet. A product that comes in round and flat stick form is likely Sil-Fos or a generic copy. Here is a link to a Sil-Fos spec sheet showing alloy and melting temperatures.

http://www.jm-metaljoining.com/products-pages.asp?pageid=64&sectionid=3

Sil-Fos comes in 2 - 15% silver whereas silver solder is above 40%. Sil-Fos is used extensively in joining copper tubing for high pressure air conditioning lines and is much cheaper (priced by the pound versus priced by the ounce). Sil-Fos also has a fairly wide plastic state where you can form it, much like working with lead on autobody repair. Silver solder changes from solid to liquid with a small temperature change.

If you have some of each on the bench a little experimenting will quickly show which one you have. Determining the exact alloy requires precise temperature control.

 

[Jasonb]

Vern are your copper coloured rods that colour all the way through or just on the outside. I have a load of steel gas welding rod that has a copper coloured coating.

Jason

 

[vlmarshall]

Vern are your copper coloured rods that colour all the way through or just on the outside. I have a load of steel gas welding rod that has a copper coloured coating.

Jason

Copper all the way through, and doesn't seem any harder, or softer, than everything else in the drawer. I meant to bring a piece of each home for photos.
All of it has been there for 20+ years, there must have been a ton at first because we use it all the time for soldering carbide inserts and such.
The copper stuff is clearly bundled and seperated from everything else... but not marked.

 

[kf2qd]

Copper all the way through, and doesn't seem any harder, or softer, than everything else in the drawer. I meant to bring a piece of each home for photos.
All of it has been there for 20+ years, there must have been a ton at first because we use it all the time for soldering carbide inserts and such.
The copper stuff is clearly bundled and seperated from everything else... but not marked.

If the sticks are slightly flattened they may be copper brazing rod. If so - they are a mix of copper and phosphorus and maybe 2% to 5% silver. They are used for joining sections of copper and brass in refrigeration applications. Get some copper tube, heat it to just red and see how the rod flows out. Used it assembling air conditioning coils.

 

[vlmarshall]

If the sticks are slightly flattened they may be copper brazing rod. If so - they are a mix of copper and phosphorus and maybe 2% to 5% silver. They are used for joining sections of copper and brass in refrigeration applications. Get some copper tube, heat it to just red and see how the rod flows out. Used it assembling air conditioning coils.

Ok, I'll try it Monday, and post photos.
The flat sticks aren't just slightly flattened, though, they're rectangular section, (tiny) bar stock.

 

[Dunc]

Used to do a fair bit of silver and gold soldering.
Used an air-natural gas flame that had plenty of
heat tho the pieces were small with little mass.

Although I have not used it I wonder if a MAPP - air
torch would provide more heat? There are MAPP-oxygen
torches as well but the cost of the small bottles and
limited burn time might make this a non-starter.