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Mervyn Passmore 2005
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Clean the surfaces to be soldered thoroughly with wet or dry abrasive paper and apply a little silver solder paste. Heat with a gas torch until red hot and then allow to cool. Remove any surplus. Silver solder paste has flux combined with paraffin wax. This is much easier to use than pure solder sticks and separate flux.

The two main causes for failure are:

Lack of cleanliness

Insufficient heat

Remember that when a gas torch states a maximum flame temperature, it relates to the heat of the flame. A micro torch may have a flame of over 1,200 degrees Centigrade, but it probably hasn't got the power to heat a large object to that temperature because much of the heat applied will be conducted away. A low temperature solder needs to be around 600-700 Centigrade to fuse, so you may have difficulty joining two heavy items, or even one small part to a larger one with a small torch. Professional torches combine gas with oxygen, which increases the power significantly.

If you are new to silver soldering, practice by joining two small nails or two brass woodscrews before you try to work on anything important. If you join them properly, you will find the join is stronger than the original material.

The join should be made quickly, otherwise large areas will discolour, and you risk overheating the whole object.

If someone has previously attempted a repair using soft lead solder, you will need to remove all traces of this contamination, or the join will fail.