What causes visible solder seams
1 Like
Usually imperfect fit, dirty joint, over heated soldering have caused it for me.
3 Likes
What Brennan says and the fact that solder is a different alloy than the metal that it is being used to join. The harder the solder, the more likely it is to be similar in color to the metal that it is joining…Rob
3 Likes
The reason you see the seam is what they call a “eutectic” joint. Because it is a dissimilar metal joint.
1 Like
Hi,
another possible cause for visible solder seams…
ie: if you need to perform multiple heating/ soldering operations, on one piece…
i will explain the best i can, but others may have more accurate descriptions…
you have a joint (ie: two separate pieces that touch)
in a sterling silver alloy
solder is a different alloy
you add solder and bring it up to flow tempurature
the surfaces on the (sterling silver) joints start to liquify
the solder flows, combining with the sterling silver alloy
creating a 3rd alloy at that interface
this 3rd alloyed area now has a higher flow tempurature, so you could carefully use the same solder a few more times without the previous joints re-flowing or failing…before you need to step down to a lower flow temp solder…
now, this is where a re-flow problem can occur…especially if you have cleaned up/ filed off and excess solder…
when you re-heat the piece, the previous solders could re-flow…the solder goes liquid, there is surface tension with the sterling…a “filet” occurs…kinda like the way water climbs up the side of a glass (where they touch)
…this filet is caused by the solder “wicking” up the surface of the metal join…if that makes sense
covering previous solder joins with a stop-flow agent will help prevent previously flowed solder joins from re-flowing…such as iron based yellow ochre, because solder needs a clean surface to flow, and yellow ochre make it “dirty”
so, i think some things to be conscious of:
do not clean up excess solder until all heating processes are completed
cover previous solder joins with a flow stop agent such as yellow ochre
plan out the # of solder joins needed, and use progressively lower temp solders for successive joins.
do not overheat the piece whan soldering
julie
4 Likes