Cleaning up solder joints


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Old 10-20-22, 04:07 PM
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Cleaning up solder joints

I have a copper watering can that needed repair on several occasions. The joint at the spout leaked and was resoldered twice. One of the handle connections came apart. So I did a complete disassembly, major cleanup and resoldered all the joints.


Spout joint

Spout joint

Lower handle joint

Upper handle joint

The spout joint is now watertight. The handle joints do not penetrate the vessel but are surface connections.

I think the joints are still too gnarly and I would like to smooth them out. I tried heating with the torch and wiping but cannot get the smoothness I would like. (Set the rag on fire a couple of times too.) Tried smoothing the surface with my large (3/8 tip) electric soldering iron but still too grainy and blobby.

I googled and found a blog about soldering copper stills that gives all kinds of advice about using abrasives to clean up the joints. I expect that I will do that.

One comment (in reply to someone's concern about loosening a joint) mentioned that a vessel with water behind the joint would prevent it from coming apart. From my experience soldering copper pipes I know very well that a wet joint will not heat up enough to melt solder in the joint. But will surface solder on a joint that is already solidly soldered heat up enough to smooth it out if there is water behind the joint? My spout joint has been such a problem over the years that I do not want to risk breaking it now that it is finally watertight.

In addition to the water issue, any other suggestions beyond sandpaper, emery cloth, steel wool, Dremel, files (including chain saw file), etc. will be appreciated.
 
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Old 10-20-22, 05:56 PM
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There cannot be any water in the can behind the repair. Water wicks away the heat.
When soldering copper it needs to be shiny clean and you need to use flux and acid core solder.
Enough heat is needed to flow the solder flat and thru the break.

I also use silver solder alloy with its own flux for stronger and neater repairs.
Silver solder kit

Since solder is softer than copper you can use sandpaper or a file to clean it up.
 
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