Identifying the grade of silver solder.

I have been gifted with a large quantity of silver solder. I don't have any provenance, except it is probably 35 years old. It has the slightly golden colour of my cadmium free 55% silver material.

I do have a small furnace, so I can probably nail the melting point of the material. with a fair degree of accuracy

My query is, will this be enough to identify the type of silver alloy. I will probably use it in boiler making (if the melting point is reasonable). So I am concerned that I can identify the material correctly.

Regards,

Andrew.

When I was gifted some solder of unknown provenance I used Archimedes Principle to work out the proportion of silver to lead. Fine for the more basic plumbers type solder but maybe not refined enough for a more sophisticated silver solders containing more than two types of metal.

Andrew - I have some older cadmium rich Silverflo 2. If it would help I could let you have a small sample to try a melt comparison test in your furnace. I have 1.5mm diameter rod and .180" x .040" strip. PM me with your details if interested and I'll get some of to you --- FOC of course!

Rik

Thanks gents,

I don't think that determining the SG would help a lot as silver solders contain quite a few elements and I don't have the apparatus to do it accurately. No sg bottle but I do have an accurate chemical balance.

Rik that would be a great help. I have plenty of the cadmium free stuff, but not the old material. I will PM you.

Thanks both,

Andrew.

Andrew,

I have several 1/4" wide strips of unidentified silver solder. I suspect that value would be in the region of £100 if bought new. I obviously won't use it for anything critical like a boiler but it might be worth seeing how you go on with your trials.

Phil H

Hello Phil,

I will keep you in the loop about melting trials.

Regards,

Andrew.

Gifted from who?

Might be jewellers solder, which also comes as flat strip.

Jewellers

Edited By Dave Halford on 15/07/2020 13:15:32

It's an interesting topic. In truth apart from expensive analysis at for example the Assay Office it will be very difficult to determine. Melt tests are fine for showing if an alloy melts at a lower/higher temperature than another but this is not necessarily an indication of the make up of the alloy. I am not a model engineer but I don't think this test would pass for a boiler inspector should that be your aim.

Samples in the post Andrew, have fun.

Rik

It came from a deceased model engineers estate. I disposed of the workshop and was given the silver solder as a "thank you" by the family.

It has been around 40 years since I built a series of copper loco boilers. At no time was I ever asked by the boiler inspector about the grade of silver solder used. I suspect that this applies even now, but stand to be corrected.. The material I have, seems to behave like the old silverflo. that I used back then.

I would like to find out what this material is for my own peace of mind, not too bothered about a boiler inspector at this stage.

Andrew.

Edited By Andrew Tinsley on 15/07/2020 15:30:50

Edited By Andrew Tinsley on 15/07/2020 15:33:16

Hello again,

I have at last managed to iron out problems with the measuring technique and have solidus and liquidus temperature measurements nailed down to plus or minus 1.5 degrees. The Easyflo No 2 that Rik Shaw sent me and my own 55% cadmium free silver solder confirmed the accuracy of the measurements. The unknown silver solder was measured at 604C solidus and 648C liquidus. This is in line with it being AG3 (Argoflo). There is nothing else that gives such a wide transition.

So it looks fine for boiler work, with somewhat larger gaps. I shall take suitable precautions as it has around 20% of cadmium as a constituent.

Thanks everyone, especially Rik Shaw for his samples.

Andrew.

P.S. This was a JIT experiment as the furnace started to play up at the end, luckily I had the measurements tied up by that time.

I have just completed a spot test for cadmium (There are quite a few available) and my silver solder has cadmium present.

There is now no doubt about it. This is AG3 (Argoflo). No other silver solder has all of the measured characteristics by a mile.

If a boiler inspector does want provenance I can repeat the experiments for him. He should be totally satisfied with the results, unless he is one of our resident nit pickers.

Andrew.

In my ignorance I would have thought that any silver solder apart from the phosphorus stuff would delight your boiler inspector.