The first thing to say is that there are probably as many ways to solder silver as there are jewellers! However, we all have to start somewhere and we offer here a basis from which to develop your own techniques. Remember, you have to learn the rules before you can successfully break them…


Tools Required:


• Solder
• Flux
• Thin paint brush (for applying flux)
• Jar of water
• Soldering block
• Tweezers
• Pickle solution
• Torch


What is Solder?


Whether strip, paste, wire or rod, solder is an alloy of the metal being joined (in this case silver) and other metals, usually copper and zinc. The purpose of the additional metal is to lower the melting point of the solder, without it the pieces you are trying to join would just melt.


Types of Solder


There are a variety of solders available but for the purposes of this article we’ll just concentrate on silver. By the time you come to work on gold, you should understand the basics anyway!


The first thing to say is that if you are planning to sell your work and/or get it hallmarked you must ensure that the silver solder you use is of hallmarking quality. Most silver items made in the UK are of "sterling silver" that is the silver content is 92.5%. To maintain the overall quality of the product the amount of solder used must be kept to a minimum and contain a minimum of 67% silver.


There are four main grades of solder used for silver work: Hard; Medium; Easy and Extra Easy. Don’t be fooled, these descriptions have absolutely nothing to do with ease of use; rather, they indicate melting temperatures, which are as follows:

 

 

Solder

Melting Temperature °C

Percentage Silver

Extra Easy

681

50

Easy

711

60

Medium

747

70

Hard

773

76

 


These different grades of solder become very important when you are soldering a piece with multiple joins. If you had just one grade of solder, every time you soldered a new join you would risk unsoldering your previous work. For this reason, when you solder a complex piece you start off with hard solder and work your way down the grades for each successive join.


If you do use the same grade of solder on successive joins then it helps if you paint earlier joins with flux (see below) before creating new joins. This will help the existing solder to flow again rather than burning out. Burning out happens with repeated heating to high temperatures and results in lumpy, blackened solder lines.


What is Flux?


Solder doesn’t flow on its own it needs something to help it along; that something is flux. Flux is available as liquid, powder and cones and the dry varieties are mixed with liquid to form a paste. Liquid flux is applied directly to the pieces you are joining. Flux also helps to prevent oxides from forming on the surface of heated metals.


The simplest of the fluxes is borax. Borax comes in the form of a cone, which is kept in a shallow dish. Borax dishes are porous so new dishes should be soaked in water overnight to overcome this.


To use borax flux: put some water into the dish and then empty; the residual water will be enough to form a paste. Using a circular motion, rub the cone on the bottom of the dish to form a paste.


Borax can also be mixed with methylated spirits, which will help to remove impurities and grease from inadequately cleaned surfaces (we’ll talk about clean soldering surfaces later).


All the solder powders are mixed in the same way as borax and, as already noted, liquid fluxes are applied directly to the metal.


Soldering Blocks


Once again, you are faced with a choice of materials! Different types of blocks have different characteristics and the truth is that almost any heat resistant surface will work, but some will work better than others. What you should never use (and there may still be some lying around) is asbestos. The risks to your health when using asbestos are grave.


Charcoal blocks are superb as they absorb oxygen from the air, reducing the amount of oxides deposited on your silver. (This is known as a reducing atmosphere). Charcoal is also soft enough to create little wells that will help you to balance curved pieces or to make evenly sized silver balls. However, charcoal blocks are not cheap and they do deteriorate with time – and quite rapidly if allowed to continue smoldering after a soldering job. Keep a spray bottle of water handy to prevent this.


The longevity of a charcoal block can be extended by wrapping it with a strip of metal followed by a band, or two, of binding wire. This will hold it together as a block when it might otherwise crumble into a number of smaller blocks.


Blocks made from garnet, ceramic, magnesia and other materials are also available, each exhibiting its own characteristics. Some are hard, durable, and very heat resistant. These will last for years. Others are soft, so that you can press pieces into them or pin work down. These tend to be more consumable. Some blocks are considered to be heat reflective, and others heat absorbing, which may also have an impact on your decision of which block to use. As with almost everything in the world of jewellery making, you need to experiment with different materials to discover which you prefer.


What is Pickle?


This is not the type of pickle you put in your sandwich! Pickle, in jewellery-making terms, is an acidic solution used for cleaning metal components while soldering. Pickle comes as liquid or powder and usually has to be diluted with water. When you realise that commonly used pickles contain sulphuric acid, nitric acid or sodium bisulphate it becomes obvious that they must be used with great respect.


If you have young children or pets, you might prefer to use alum or citric acid, both of which are effective substitutes for the more lethal recipes.


Pickle Containers


Pickle is, as we’ve just said, an acid. It also works better when it’s warm, so you need a container that can deal with both heat and acid. Some suggestions are:


• A small slow cooker (one-person size) is a good container for holding your pickle. It can be left on a low heat and the lid should be kept on to reduce evaporation. There have been reports that, over time, the acid eats through the glaze on the crock pot, to avoid this use a bain-marie type set up. Put plain water in the crock pot and your pickle solution into a glass dish, which you then stand in the warm water.
• A small Pyrex casserole dish with a lid can be used and kept hot on a warming tray or hotplate
• A glass preserving jar makes a useful container as it is small enough to stand on a cup warmer
• Many jewellers also use baby bottle warmers with great success.

In the next part, we'll tell you exactly how to use these esoteric ingredients...


Contributed by Di Sandland
www.mooncottagejewellery.co.uk

44 Hockley Street

Hockley

Birmingham

B18 6BH

Tel: +44 (0)121 507 0994

Company number 07258309

ICO Registration No: ZA460029