I’ve worked for two weeks on a strange problem in my workshop and
now I’ve run out of ideas.
The problem occurred when a claw in a basket mount came loose. The
solder joints were bad.
I then discovered that when I hard solder a sterling silver wire to
a sterling silver plate, the solder flows and looks good but
afterwards the wire can be pulled off and the solder stays on the
plate with a perfect imprint of the wire.
I started an investigation and in order to judge the quality of the
soldering process I made a standard layout: wires are numbered and
placed on a 0,5 mm silver sheet, the wires protruding a bit from the
plate. If they tend to roll, I separate them with small stiches in
the plate. Unknown wires are tested in pair together with a bad and a
good wire. They are soldered with hard solder and pickled. To test
the strength I take a pair of pliers and pull. If a wire is good, it
should not be possible to remove it from the plate.
I have replaced everything in the soldering process with new stuff;
charcoal, solder, tweezers, solder, flux, gas. I’ve ruled out the
silver, the amount of solder, the cleaning procedure, the heating
technique, the acid, the draw plate, the mineral oil for drawing
wire, the water quality, the size of the wire.
There is two things left to test, the brick I use to anneal on (not
likely the problem since I use it when drawing wire) and my 2 years
old Durston 100 Minimill combo. Purchased untreated wire works
perfectly and the same goes if I draw the wire but if I roll the wire
it doesn’t work, it won’t solder.
The rolling process works good and I anneal and pickle after 50%
size reduction. I occasionally get some flaking or thin hairs along
the edges of the wire which I remove by sanding. The rolled silver
wire look ok but has a greyish color that I do not remember having
seen before. I’ve clean the rolls with acetone but there was no
difference. I do not know if I’ve had this problem before because I
have not tried to pull off a soldered wire.
Now I am out of ideas for further testing and I hope that any of you
have any suggestions to what I can do.