Silver solders or brazing alloys and their use.

Peter G. Johns. (2006) Silver solders or brazing alloys and their use. [Patent] (doi:UK Patent No. GB2408269 - granted 22/2/2006.)

Abstract

The UK has hallmarking laws that govern the minimum amount of silver that must be present in solders for joining sterling silver. The minimum quantity is set at 65% silver. Many other countries allow solders with lower silver content of 55%. Higher silver solders usually have higher melting and working temperatures, which require higher levels of skill to use and can cause distortion and deep firestain in the piece being soldered: this can lead to increased and expensive finishing costs. Lower silver content solders offer lower melting and working temperatures, however a disadvantage is a decrease in the whiteness of the solder, which causes solder seams to become clearly visible on finished pieces, thus limiting the creative scope of the designer/maker.

Silver solders for jewellery and silverware have remained the same for at least 75 years. The challenge of this research was to provide solders that:

- conform to UK hallmarking laws
- are easy to use, with low temperature flow properties that are normally found in the lower silver content solder alloys
- have a good white colour to match the colour of Argentium Silver
- have good tarnish resistant properties

The patent granted from this research and the commercial alloys produced by Stern-Leach in the USA derived from over 40 individual solder alloys, made and tested at Middlesex University. A range of paste solders has also been developed for furnace soldering operations.

Current work is being conducted with designer/makers in best utilising these new solders.

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