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Silver Solder & Braze

Thursday, 19th March 2020
Graham (Tech Advisor)
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Silver Solder & Braze are both products used with either an Oxy Acetylene Torch or Oxy Propane Torch.

Silver Solder & Braze, what’s the difference?

For me, the key difference is how they work on the joint.

Silver Solder

Silver Solder is more fluid than Braze and works by being drawn into the joint by a capillary action.  So if, for example, you want to join two pieces of thin sheet metal together, you would need to overlap them.  The Silver Solder will be drawn through the joint, filling the minute crack between the two pieces of metal, bonding with the surfaces to join them.  If you tried to butt the two pieces of metal together, there simply wouldn’t be enough surface area touching to achieve a strong joint.

Silver Solder is used with a Flux, which chemically cleans the metal and keeps it clean during the Silver Soldering process.  Silver Solder is also know as Silver Brazing.


Braze on the other hand, does not get drawn into the joint, but is built up on the surface of the metal being joined, so it looks more like a weld.  Like Silver Solder, the Braze material bonds with the surface of the metal being joined.

Braze is used with a Flux, which chemically cleans the metal and keeps it clean during the Brazing process.  Brazing is also known as Bronze Welding.

What Silver Solder & Braze have in common is that neither involve melting the metal that’s being joined, that would be welding!

In the joint examples shown, I would use Silver Solder on the Edge & Lap Joint and Braze for the Butt, Corner & Tee Joint.

Types of Silver Solder & Braze

Whilst there are a number of Brazing Alloys on the market, for this article we’ll keep it simple and just cover the most common, C2.

C2 is a multi purpose, Silicon Bronze brazing rod that’s suited to most general purpose brazing on metals including Steel, Copper, Cast Iron and dissimilar metals.

C2 Braze is Brass Coloured and typically melts at around 875⁰C.

Most Silver Solders can be categorised by their Silver content.  The Silver content will determine the fluidity and melting temperature, the more Silver, the more fluid and the lower the melting temperature.

Most common are 33% Silver (around 720⁰C), 40% Silver (around 675⁰C) and 55% Silver (around 650⁰C).

Also available are Silver bearing Copper Phosphorus Alloys (CoPhos).  These are available with either 2% or 5% Silver and are used primarily for joining Copper to Copper, where, if the metal is clean, no Flux need be used.

Silver Solder can be used to join most common metals, including Mild Steel, Stainless Steel, Copper, Brass, Cast Iron and Dissimilar Metals.

Fluxed or Bare Wire?

Silver Solder & Braze is usually available in 2 or 3 forms:

  1. Bare Wire – (Silver Solder & Braze). This is my preferred type.  With this wire you use a powder flux.  This can be coated onto the wire as necessary by gently warming the end of the wire in your flame, then dipping in the powder.  This can be repeated as necessary.
  2. Flux Coated – (Silver Solder & Braze). This may seem like a good idea, but there are, for me, three flaws.  Flux coated wires are more expensive than bare wire.  If you need additional flux, you’ll still need a pot of powder. If the wires are bent, the flux tends to fall off!
  3. Flux Impregnated – (Braze Only). Here the flux is in little nicks on the wire.  This works very well and the wires can be bent.  The downside is that flux impregnated wires are the most expensive.

I hope you found this blog article useful, if things work out well for you, please feel free to post some pictures of your achievements on our Facebook Page

Please let me know what you thought of this article by leaving a comment.  Don’t worry, your email address won’t be added to a database or shared and you won’t receive any unsolicited email.



The Welders Warehouse

9 responses to “Silver Solder & Braze”

  1. Ray Farrell says:

    Really enjoyed the column Graham.
    I’m putting a bush fire sprinkler system around the house under the gutter.
    I’m using copper but soft solder melts at too low a temperature and has been known to fail in fires.
    A solder rod manufacturer recommends 2% silver solder rod (which I assume is a phos Copper rod). I’ve never silver soldered 50mm Cu before. I’m going to use Oxy Mapp gas.
    What should I look out for compared to soft soldering 19mm tube.

  2. Andrew Michael says:

    Great colunm, I have a question, I’m trying to put a mast mount which is 6″*6″ carbon steel about 1/2″ thick, on a cast iron counterweight that is on a excavator. I was wanting to ask you for any ideas or suggestions for this application and would silver soldering be a feasible application. This counterweight is huge and there is no way I could heat the whole thing.

    • Graham says:

      Hi Andrew
      Thanks for the positive comment, much appreciated.
      Re your Cast Iron Counterweight on to ½” thick box steel. I don’t think Silver Solder would work as you will need to gat the parts VERY Hot. I would warm up the Cast Iron so that it’s not cold (doesn’t need to be hot), so warm to touch, at least around the area to be welded. Then use Ferro Nickel Cast Iron Arc Rods to Weld them. Alternatively, could you use a non heat method? Tapping the Cast Iron and bolting for example?
      Hope I’ve helped, at least a bit 🙂
      Cheers Graham

  3. davidokkefe says:

    Brazing and soldering are classed as semi permanent opposed to welding which is permanent brazing would be achieved by capillary action as well excellent technical information graham enjoy reading comments

  4. Michael Poore says:

    In the motor trade we found that repairing exhaust brackets & similar items [a lot of vibration] the repaired item was stronger than the original item!

  5. Adrian says:

    Very helpful and succinct! I presume the silver solder and braze wire mentiond is available on the website, along with the fluxs?

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