It's the tin in solder that weathers from moisture. The water leaches
out the tin and leaves a soft, porous matrix that has very little
strength. The white powder you often see is the lead oxidizing after
the tin has gone. The less tin the better, but unfortunately that also
usually raises the melting temperature. Plumbing solder is a bit of a
compromise, but lasts much longer than standard lead-tin solder.
Solder of any kind should never be used for structural strength, which I
why I agreed with the folks who suggested using some other means (like a
rope) to handle the tension and then leave a loose tail for the
electrical connection (solder, split bolt, whatever).
73,
Dave AB7E
On 7/13/2021 5:45 AM, Lux, Jim wrote:
On 7/13/21 4:52 AM, john@kk9a.com wrote:
Like many posts, this went off on a tangent. If it was for connecting
two
parallel wires, I would have suggested the western-union splice. I
use this
splice all the time on dipoles and Beverages. I use regular lead solder
without issue but perhaps they are not up long enough to see lead
degradation. Interesting post on using plumbing solder, that should be
easier to use on the tower than silver solder.
John KK9A
Plumbing solder is still soft solder, used to be 50/50 lead/tin but is
now Tin, Copper, Nickel, and Silver (and other stuff with low melting
points like indium), but is still not hard solder, and is not structural.
brazing and hard soldering uses higher melting alloys (high silver
content, copper) and is significantly stronger, and much less likely
to become brittle than the tin based alloys used for soft soldering.
I don't know that solder degrades from weather, per se (i.e. it
doesn't oxidize or chemically change from exposure to air and water)
However, it work hardens easily, so mechanical loading or temperature
cycling (which creates mechanical loading in some cases) can make it
brittle. Soft solder also has creep and deformation under constant
load. Tin/lead solders can form two kinds of crystals, so cracks can
develop between the crystals, which combined with temperature cycling,
can cause degradation.
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