Working with Silver


Melting temperatures


It is important to be aware of the melting point of your chosen metal to enable you to choose the appropriate soldering torch and solder. Sterling silver has quite a low melting point in comparison to other precious metals, making it easier to use with some of the lower temperature blow torches.


925 Sterling silver > melting range 805C – 890C Britannia silver > melting range 890C – 940C 999 Fine silver > melting range 961C – 961C (The first temperature is when the surface will start to melt and the second is when the material will become molten)


14 The Art of Melting...


Fire stain: Fire stain occurs when sterling silver is heated for prolonged periods which cause the copper content to oxidise in the air, forming dark shadows on the metal surface. Often these shadows will only become visible during the latter stages of production and the only way to remove them once they appear is through repeated buffing with emery paper and polishing, (for light staining) and in the most serious cases silver plating.


Preventing Fire stain: The best way to deal with fire stain is to prevent it from occurring in the first place and there are several ways to do this:


n Avoid heating silver for prolonged periods. Ensure your soldering and annealing operations are efficient and completed as quickly as possible with the correct size torch and flame for the job.


n Quench heated silver in a Picklean or pickling powder solution to avoid the build up of oxides.


n Paint the surface of your silver with flux before heating. This will form a protective, transparent coating which should prevent oxides from forming.


Avoiding Cracking: Oxidised copper (i.e. fire stain) is extremely hard. If this is forced into the body of the metal through continuous working without removal, these areas will eventually become brittle and crack. To avoid cracking either:


n Quench silver in picklean or pickling powder solution after every heating operation, both annealing and soldering.


n Coat silver with Argo-tect to provide a protective layer thus preventing the formation of oxides.


Annealing: Annealing is the heating of metal to relax the internal structure making it easier to work and shape. As metal is worked, the structure becomes compacted making it harder and more difficult to move which is known as work-hardening. If this continues, the metal will eventually become brittle and may eventually crack so it is essential to anneal your silver at regular intervals throughout a job to keep it soft.


Tip: It is possible to buy both flux and solder combined in a soldering paste which essentially does two jobs in one. It comes in a syringe which means it can be applied with great precision, ideal for more delicate work.


Sterling silve melting poin other preciou it easier to us


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