Jewellery making

Solder paste

I have a reputation for being against the use of solder paste. Many a time I see furtive glances across the studio during setting up for soldering, when the use of paste is on the agenda.

However my reputation is unfounded. I am not against the use of paste at all and use it frequently when making my own jewellery. I also sometimes suggest appropriate times to use it in the studio workbooks. (see the downloads page for the studio workbooks) It has a definite place in our jewellery making procedures, but it is not something that can replace traditional solder completely. It is great for some things and terrible for others. The knack is knowing when to use it.

What is solder paste?

soldering past

Solder paste can be used to solder in tricky situations, it is available from the studio shop.

Firstly an explanation of what paste actually is. Basically it is finely ground solder and flux mixed together to resemble a soft clay like substance. It is available in both silver and gold. I will be honest here, because I don’t work in gold I have never bought or used any gold solder paste. It is available in yellow, white and red gold, easy, medium and hard. Silver solder paste is also available in easy, medium and hard.

It is a fairly expensive material to buy especially in gold. As a rough idea 3 grams of 9ct gold easy solder paste is just a bit more than double the price of 30 grams of silver solder paste. Silver solder paste is roughly 50{f2a72205b26169d703bc4f88b64a1e954ccd9f013dcdaccc41f0b2fc1885123f} more than the equivalent silver gram price. However, it does last a very long time because it is used in such a precise manner. It is supplied in a syringe – sometimes with a dispensing needle.

The Great:

So what is it good for exactly? The best use for it is when soldering small components together which can be easily moved around by the fizz of traditional flux. It is great for ‘sticking’ delicate components on to large components that cannot easily be sweat soldered. It is also great for soldering wrapped or twisted wire components where a big glob of solder will stand out or totally obliterate detail.

How to use it:

Remove the lid from the end of the syringe – if you want to use a needle then twist this needle on to the end of the nozzle where the lid was. Press the plunger in to the cylinder until a small amount is pushed out of the end. Don’t forget to replace the lid – it can dry out! This can be added in a very precise fashion on to the components to be soldered.

It can be a bit of a tussle getting the paste to dispense easily out of the needle – you may find you need hands like Arnie or sly Stallone! If it is a real struggle then remove the needle – the paste will come out of the hole at the end of the syringe much easier. Either apply it directly as with the needle, or squeeze it out on to your fingertip. This can be ‘wiped’ in to nooks and crannies like wrapped wire or findings. I never use my paste with the needle, I have always found it really counterproductive. I find that so much pressure is needed to squeeze the paste out of the tube that it is impossible to have a steady hand.

Once you have the solder paste where you want it – heat your work in the usual way. Make sure the solder runs and shimmers like traditional solder. Pickle as usual. If the paste hasn’t quite run fully in to join – but there is plenty of solder left on then it can be re-heated. Just add some normal flux to the join first. It takes a while to get the hang of judging how much paste to use for your join. 

The Terrible:

What is it not so good for? Major seams – like the main join on the back of a ring for instance. It doesn’t ‘pool’ or ‘flow’ like traditional solder. It tends to ‘sink’ into joins so a main seam will stay visible without an excess to file back. Just apply more? Not really – this tends to result in a real ‘blobby’ mess to clean up. In-fact it doesn’t ‘fill’ joins well at all. If you cut jump rings with side cutters instead of sawing them – then traditional solder will fill the little ‘v’ gap made by the cutter to a certain extent. Solder paste won’t!

Solder Paste will join sawn jump rings neatly but I have never got on with it for this either. I often find that once the wet element of the paste has gone during heating, the paste shrivels up and the tiny bit of solder left behind, precariously balancing on a thin wire, falls off. This crumbling ‘powder like’ solder left behind is then very difficult to pick up with tweezers.

Finally –it still has to flow like normal solder. A join can be brittle if the solder paste hasn’t reached temperature – it may still join unlike traditional solder in this situation, but it will be weak. Recognising when this has happened will come with experience. 

A dry problem

If you leave the lid off your paste (or store it on a sunny windowsill like I did!) and it dries out, it can be saved by adding a little water to it. You may also find that the last dregs in the tube can be a bit dried because a little paste goes a long way and the tube may have been in use for a few years. Getting the water in to the tube can be a bit tricky! If the plunger will pull out then you’re in luck and you’ll be able to dribble a bit of tap water in and stir it around with a bit of wire.

However the plunger can form a vacuum which even Arnie would struggle with! The best thing to do in this instance is to just squeeze a small amount out and mix it with water each time it is needed. If it really won’t come out then a Stanley knife might be the only answer. Destroy the tube, scrape out the paste, mix it with water and store it in a new air tight container. I’m sure there are purists reading this and cringing – but I’ve done this with (silver) solder paste and it’s been fine.

The Trap:

Because it is such a great way to solder often the most difficult joins, the novice can be completely bowled over by solder paste. The revelation after discovering this saviour in the silversmithing world often results in vows of ‘never using normal solder again’. But beware of turning your back on our old friend. Traditional solder can sometimes be tricky to use but is often the best way to make a good join. Each has their appropriate use. If you struggle with traditional solder then persevere and use it more, you will get better and your jewellery will be better. If your work involves small findings and wire details then give solder paste a try.

Hard and Easy silver solder paste is stocked at Silverpetal’s Studio Shop. Don’t forget – if you ever need any advice – just ask. Happy soldering!

 

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