How do you use copper solder?
If you already know how to solder sterling or fine silver, then you already know how to solder copper. If you have no soldering experience, or have only used “soft” solder and soldering irons before, then copper solder is an EXCELLENT material to begin with.
So, where do you begin? At the very minimum, you need:
Raw (bare, unplated) copper
A torch that gets hot enough for the job — but a soldering iron does not get hot enough
A firing surface
Something to grab melty-hot metal items
Generally, you’ll drop your freshly-soldered item in a pickle pot or a metal can full of cool water. And there are safety considerations … you don’t really want to catch your clothing or kitchen/craft table on fire, or breathe or splash unknown chemicals, so if you’re completely new to soldering, pick up a book like Simple Soldering, by Kate Ferrant Richbourg, or Soldering Made Simple, by Joe Silvera.
There’s lots of good advice online and in books on how to solder, the most important points are:
– Make sure your joints are absolutely perfectly flush with each other (solder does not fill gaps, ever) and if there’s any risk the join might open up during soldering, use binding wire or other suitable methods to keep it tightly closed. If you do this perfectly (and it’s not easy), you shouldn’t have a visible silver line on your copper or brass piece.
– Clean very well and flux the joints carefully, this will help your solder flow where you want it to flow by preventing oxidation as you heat up the metal.
– Heat the metal, not the solder, don’t use too much solder and make sure the whole joining space is an even heat, to make the solder flow evenly. The flux will burn off and the solder might ball up before flowing. As a general guide, when you see a flash of silver across the joint, remove your torch – the solder has flowed.
– Pickle copper – and follow Drake’s advice about electroplating if you have a visible silver line. Brass is made from copper and zinc and pickle can remove the surface zinc (this is fine if you want a pink piece), so it’s better to boil any remaining flux off in plain water.
– When you’ve polished and finished your piece, I’d recommend using a microcrystalline wax (such as Renaissance wax – a small tin lasts a very long time) to seal it. This prevents oxidation.
Practice lots on scrap pieces, try to get a feel for the right amount of solder needed.
Good luck with your new skill!