When soldering copper pipe, what does the flux do to cause the solder
to get drawn into the joint? Something to do with capillary action?

On Jun 5, 12:10 pm, Doc wrote:
When soldering copper pipe, what does the flux do to cause the solder
to get drawn into the joint? Something to do with capillary action?

If I understand it correctly, the flux chemically performs a final
cleaning of the surfaces, prevents copper oxides from forming, and
also does help draw the solder into the joint. You can even buy
what's called a "tinning flux" which contains a small amount of solder
and helps make a more reliable joint.

nate

On Jun 5, 12:14 pm, N8N wrote:
On Jun 5, 12:10 pm, Doc wrote:

When soldering copper pipe, what does the flux do to cause the solder
to get drawn into the joint? Something to do with capillary action?

If I understand it correctly, the flux chemically performs a final
cleaning of the surfaces, prevents copper oxides from forming, and
also does help draw the solder into the joint. You can even buy
what's called a "tinning flux" which contains a small amount of solder
and helps make a more reliable joint.

nate

As I understand it, nate is correct. The solder flows into the joint
because the joint is hot and it melts the solder. The heat along with
the close surfaces (capillary action I assume) causes it to draw into
the joint. You can solder without flux, but it is not recommended for
the exact reasons that nate mentions.

On Jun 5, 11:19 am, Doug wrote:
On Jun 5, 12:14 pm, N8N wrote:

On Jun 5, 12:10 pm, Doc wrote:

When soldering copper pipe, what does the flux do to cause the solder
to get drawn into the joint? Something to do with capillary action?

If I understand it correctly, the flux chemically performs a final
cleaning of the surfaces, prevents copper oxides from forming, and
also does help draw the solder into the joint. You can even buy
what's called a "tinning flux" which contains a small amount of solder
and helps make a more reliable joint.

nate

As I understand it, nate is correct. The solder flows into the joint
because the joint is hot and it melts the solder. The heat along with
the close surfaces (capillary action I assume) causes it to draw into
the joint. You can solder without flux, but it is not recommended for
the exact reasons that nate mentions.

It also serves as a wetting agent which is what helps the capillary
action and to ensure full joint coverage.

--

On Tue, 05 Jun 2007 09:10:53 -0700, Doc wrote:

When soldering copper pipe, what does the flux do to cause the solder
to get drawn into the joint? Something to do with capillary action?

What he said. It keeps the copper from oxidizing, or 'rust'ing. And wen
you add the heat it would oxidize faster. Solder does not take to copper
oxide as I understand it. so flux helps to keep the weld area clean.

On Jun 5, 1:02 pm, "dnoyeB" wrote:
On Tue, 05 Jun 2007 09:10:53 -0700, Doc wrote:
When soldering copper pipe, what does the flux do to cause the solder
to get drawn into the joint? Something to do with capillary action?

What he said. It keeps the copper from oxidizing, or 'rust'ing. And wen
you add the heat it would oxidize faster. Solder does not take to copper
oxide as I understand it. so flux helps to keep the weld area clean.

Stick the hot tip of your soldering gun/iron in a tin of flux and see
how clean & shiney it comes out. That's what it does for the joint.

Red

In article . com, Doc wrote:
When soldering copper pipe, what does the flux do to cause the solder
to get drawn into the joint? Something to do with capillary action?

The main thing I see is preventing oxidation of the metal, even reacting
with oxygen in the oxide to remove some of any existing oxide for some
metals, including copper and lead/tin, whichever of those in "ordinary"
solder tends to oxidize when such solder is molten.
Some metals are reactive enough for their oxides to be unable to be
reduced by flux, with aluminum being a prime example.

- Don Klipstein )

Don Klipstein wrote:
In article . com, Doc wrote:
When soldering copper pipe, what does the flux do to cause the solder
to get drawn into the joint? Something to do with capillary action?

The main thing I see is preventing oxidation of the metal, ...

True, but the wetting action is also important in helping w/ solder
flow...similar to detergent w/ water on dry glass--it tends to "clump"
rather than flow alone, but a drop of detergent "breaks" the surface
tension. That same action is what helps to ensure full coverage and
the takeup in the joint.

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