What are its pitfalls? Why isn't it used more frequently? It
sounds like it would be very handy when soldering findings when
the regular solder jumps around etc.
I’m not an expert on when & where to use paste solder. I only
know what works for me, however, I’m not adverse to trying new
techniques or products or old products for a new application.
Sometimes some of the new
techniques/products even work!
I got started using paste solder for soldering links together
for chain. It’s a pain in the butt, not to mention time
consuming, to cut solder sma ll enough for some of the links.
Paste solder is available in sterling, gold filled, various gold
karats & all the typical melting temps. I don’t know if the golds
are available in other than yellow. The solder (that I use) is
delivered in plastic syringes with 2 interchangable needles, a 16
& 20 ga. The golds are 1dwt & the sterlings 0.5 oz to the
syringes. The paste consists of a powdered solder, a flux &
transport vehicle which I believe is glycerine. The labels on
the golds indicate the flux may contain flourides & cadmium. The
sterling label states it contains flourides. The sterling is
about $7.00 if I remember correctly. A syringe lasts quite a
To use, select the needle appropriate to the job, place the
needle tip close to the join to be soldered & squeeze the solder
from the syringe. The needle tip should be close enough to the
join so the solder can contact both sides (right & left) of the
join. The solder will adhere to the meta l. As with any
soldering, the join must be tight, paste solder is not a ‘gap
filler’. I don’t know if there’s a maximum time during which the
join must be soldered, but I’ve been interrupted & applied the
heat to the join a hour later with no problems. Usually I apply
the heat within 10 minutes if I’ve got a lot of joins to solder.
After soldering, the piece goes in the pickle; I use warm
Sparex, with no problems.
The idocyncrasies of paste solder are:
1.Syringe will leak if left uncapped (the vehicle oozes out).
2.Needles cake if not cleaned out before storage.
3.Paste is hard to eject if syringe is old.
4.Index & middle finger can get sore from syringe.
5.When applying paste, be sure to keep it where you want it; when
it reaches the liquidus point it melts almost instantaneously.
6.Putting the needle against something that is hot will cause the
paste t o cake in it.
There are simple solutions for each of the above.
1.Put the cap on.
2.Insert a wire of the appropriate size when finished with a
3.Warm the syringe under a warm, wet washcloth or a light bulb.
4.Use a solder aid to reduce the strain on the fingers & give
yourself more leverage.
5.Be careful when applying paste; remove any ‘oops’ before
6.Keep the needle away from hot metal or use the wire to clean it
In all fairness, paste is not the solder of choice for all
applications. Sheet & wire solder are going to be around for a
long, long time. Paste i s great to use if the join is in an
awkward position & it’s hard to get pallions to stick. Paste is
Hope this helps.