Solder won't flow on copper

I have recently learned to solder sterling silver and am having much
success with it. I have tried soldering copper wire (18 gage) using
the same techniuqe with no success. Basically the silver solder
won’t flow. I prep copper very well with a tight joint then clean it
in the pickle. Then I flux (have tried both batterns and past flux)
both the joint and the solder. I have tried balling solder on the
pick first and also laying directly on the joint and then heating. I
am heating with the same butane mini torch I use for silver, keeping
the flame always moving. I have tired low flame (what I use for
silver), medium and high. I can sometimes get the solder to ball up
and even turn that shinny mercury liquidy color, but no matter what I
do it will not flow through the joint - even when I try to push it
down into the joint with the pick.

HELP please.

Copper is a “dirty” metal and it is always a problem to “clean” it
well and then: keep it clean" while heating so the solder will flow.
You might try using a flux “made” for copper rather than a flux for
silver. Remember, copper is a “dirty” metal; when heated so that
one MUST take/use precautions that are not so necessary with silver
or sterling. You might try using handy flux for a fluxing material.
Also, get it hot fast and get the job done as fast as possible to
keep oxidation time to the minimum. Also use fire guard (50/50 mix of
alcohol and boric acid) as soon as you clean the copper, then flux
with handy flux and get the soldering done ASAP!!

Good luck. Copper is just a tough metal to solder at high temps…

John Dach

Hi Heather!

I’m certainly no expert, but it sounds like you are heating the
solder, not the wire. The solder should melt from the heat of the
copper, not the torch. Copper conducts heat even better than silver,
so make sure the whole piece is hot enough before focusing the flame
near the join.

Sarah in Wales

Hello Heather, It sounds like you do not have enough heat to get the
copper up to temp. Copper melts at a much higher temperature than
sterling, so don’t worry about melting the copper! However, your
little butane torch may not be capable of generating enough heat -
especially if the copper piece is very large.

When I solder copper using sterling solder, I use Battern’s flux
generously, place (or use the pick) the solder, then really turn up
the flame and get the copper red hot. Flow happens.

Hope this helps,
Judy in Kansas, where it was a breezy warm day - finally started
cleaning up the flower beds.

Heather - You are getting the solder hot, but you are not getting the
copper hot enough. Focus on heating all of the copper. Not just the
area where you want to solder. When it gets hot enough then focus
your torch where you want the solder to flow. Be sure to use paste

Have fun and make lots of jewelry.
Jo Haemer

I have used copper colored solder for several years and it works well
to solder copper wire and sheet metal. The flux is included and the
solder remains a copper color on your joints. The small butane torch
is not hot enough for the solder to flow. You may use a plumbing
butane torch that reaches approximately 3,400 degrees or any other
torch that heats at a higher temperature. I hope this helps.


Dear Heather,

The problems with soldering on copper that I can detect from your
post aRe:

  1. Using a Butane Mini Torch, it does not always offer enough
    constant high heat for copper.

  2. Using Batterns Flux, it is for silver and gold applications,
    copper oxidizes too quickly and needs a paste flux.

  3. Keeping the flame always moving, with copper you need to focus
    the flame at the join after heating up the whole piece.

  4. Trying to push the balled solder with the pick, this action will
    actually cool the solder, since the pick will act briefly as a heat
    sink when introduced to the procedure.

Over all it sounds like you are not getting the copper hot enough
fast enough. A common problem when switching from silver soldering.
Copper sucks up a lot of heat and does not hold it as well as silver.
Also try soldering on a compressed charcoal block. It will hold the
heat and make the process a little easier.

Nanz Aalund

Hi, Linda. What is the copper solder that you use, and where can I
find it? I solder a lot of bronze, and I’d like to find a solder
that works well on bronze. I’ve had a great deal of difficulty
soldering my bronze. I’m assuming your copper solder would work great
on bronze too.

Hi John,

The solder is called “copper colored solder” and it can be found at

Copper Colored Solder (beadmeus)

I have not used it on bronze. The copper colored solder requires a
high flame temperature.


Thanks, Linda. I remember you mentioning that you don’t need flux
with this “copper colored solder”. I am going to order some from the
site. I didn’t see any instructions on the site regarding flux. Do
you use flux? If not, do you cut the solder rod into small pieces
and use it that way? Or do you just touch the rod to the area you’re
soldering once you get the area hot enough?

Please give me more on this solder, as I am ordering
some right now for my bronze work.


John, or you can go to your local welding supplier and buy a tube of
’copperphos’ (some people call it ‘phoscopper’). We cut it into
small snippets and it works just great on copper.

Cheers from Don in SOFL

go to your local welding supplier and buy a tube of 'copperphos'
(some people call it 'phoscopper'). We cut it into small snippets
and it works just great on copper. 

Thanks, Don. Do you need flux with the copperphos? Can I use it on
bronze? I don’t really use copper in my work, but bronze is mostly
copper, so I’m wondering if I can use the copperphos to solder

Hi Don,

Is the flux included in the phoscopper?


Is the flux included in the phoscopper? 

Copper phosphorous brazing alloys dont need flux. The phosphorous
acts as a deoxidizer during brazing.

James Binnion
James Binnion Metal Arts

Yes, flux is necessary. I like handiflux but try a number of others
and use what works for you. It works on brass, copper, and bronze.

Cheers from Don in SOFL.

Thanks James. While you are correct, we have found that we get better
flow of the solder by using handiflux.

Cheers from Don in SOFL.