Brazing and Soldering- The Difference is Crucial

Technically soldering is done at lower temperatures and brazing is done at high-temperatures. The separation point is usually about 800°F.

A braze joint can be somewhere between 10 and 100 times as strong as a solder joint.

 There is silver soldering which is using solders with 1 or 2% silver.  The term silver soldering is often misused, when the proper term should be silver brazing. In Silver Brazing the material is 30 to 60% silver.

One key reason that this is so important to differentiate is that somebody who wants to do silver brazing will go into a welding shop and ask for a flux for silver soldering. The welding shop will sell them an excellent soldering flux which will not work at all for silver brazing.

Soldering flux is designed for low temperatures and will burn up and become completely ineffective before you even reach brazing temperatures.  For Silver brazing it is important to use brazing flux.

Flux is somewhat of a cleaner and oxide remover but it is best not to use it that way. Start with clean, oxide free materials and use the flux purely as an oxygen interceptor. 

If you’re using is solder flux with the braze alloy then the solder flux will absorb all the oxygen it can at low temperature.  By the time you hit the melting point of the braze alloy there will be no oxidation protection at all and the braze alloy will burn up instead of flowing out.

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