Friday, 13 March 2015

Experiments in using solder paste

Generally when joining metal I use sheet solder, which is economical and in most cases, easy and fast to use. But sometimes it can be a pain to get solder in place around a particularly tiny piece, so I thought I'd have a go with silver solder paste instead. It's a bit more expensive but it lasts for ages.

I'm starting out with a plain silver ring, to which I'm going to solder some silver and copper blobs. Blobby blobby blobby!

OK, right. Here we go. Excuse my fingernails, I've been testing out gilding nails with copper leaf. It actually worked pretty well, this is a few days afterwards..

Dot punch to start with. Stops the drill skipping off the surface of the ring.

Bzzzzzzzz. Only drill a bit into the surface, don't go all the way through.

Repeat until lots of holes.

This is fine silver casting grain, usually used for melting down prior to turning into other exciting stuff, but this shape is exactly what I want for this ring.

Carefully applying the solder paste. A tiny dab is all that's needed.

The paste is a mixture of finely ground solder and flux, so it doesn't need more flux. It's slightly sticky, which is perfect for helping hold this in place.

Flame on! That's the first two bits of silver joined on OK, but I wanted some copper too. You can get copper casting grain but I don't have any, so I'm going to make some little copper blobs instead.

A short length of 1mm diameter copper wire, perhaps 15mm or so long. Wire placed on a heatproof surface and heated will melt and pull itself into a sphere - it's pretty magical.

There, two little glowing blobs of copper. Let them cool down, then a quick buff with some sandpaper and they're good to go. Soldering them on to the ring is the same process as before. Do that a few times and...

Ready to polish. 3M radial polishing brushes are pretty much essential to get into those little nooks and crannys. Cleanup is about half of the work involved in this piece!

So yeah, solder paste is pretty neat. I don't expect I'll use it all that much for day-to-day soldering jobs, but for the few things like this that it's great for, I think I'll be glad to have some around.

The reflections in this ring make it look a bit weird, I might have to reshoot these photos. Came out nicely though.

You can buy this ring here.

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