To Silver Solder You Will Need:

·        Flux (paste)

·        Silver Solder Rod (thin)

Quick Start Instructions:

Soldering a copper pipe to a brass boiler (for example).

·        Clean the join areas with emery paper - if necessary.

·        Using your mini blow torch, do not heat up the boiler too much as you will damage the paint unnecessarily.

·        Do not dismantle the piston assembly from the engine as this acts as an important heat sink that stops other pipe joins from melting too.

·        Use silver solder because lead solder will not take the heat long term.

·        Use a small silver solder stick.

·        Use flux paste.

Apply flux to the two contact areas avoiding getting it on places you do not want the solder to run to (otherwise you'll get too much around there).

Heat up both surfaces at the same time and then touch the silver solder stick on each surface.

Place them together, apply the torch causing the solder to flow around the inserted pipe and then immediately withdraw the heat.  It will be solid in seconds.

Detailed Instructions:

There is nothing particularly difficult about silver soldering; it is just a matter of getting the methodology right. Like most things in life, if you don't try it you never will succeed. And when you succeed, practice a bit more and you will be amazed at your results.  So, here we go.

Let's say at first that a botched silver soldering job is a real eye-sore so it's as well to get some practice on scrap bits or non-critical jobs. The main fault that is seen (apart from using insufficient heat) is an excess of solder used on the joint resulting in it flowing all over the work.

The secret of silver soldering is as follows:

• Close-fitting joint prior to soldering.
• Making sure the work is CLEAN before starting.
• Fluxing the work thoroughly (using the right flux).
• Using the correct amount of heat.
• Using the correct amount of solder (and size of rod) for the job.
• Applying the solder at the correct time and place.
• Controlling the flow of the solder.

There are several grades of silver solder, and some flow more easily than others (it is the silver which provides the free-flowing characteristics). But in no case is silver solder good at gap-filling - this is opposite to that other useful property it has which is to creep into every nook and cranny. Because of this your pieces for soldering need to be close - not more than 5 thou apart.

It is absolutely essential that the joint faces be quite clean and oil-free to obtain a sound joint. The solder will not flow across nor bind to a dirty metal surface. All joint faces should be cleaned with emery and/or wire wool to brighten the metal surface. Always wear eye protection.

Regarding the use of flux. Make sure all joint faces are thoroughly coated and dribble some extra along the joints to make a fillet to be sure. The first application of heat should be gentle to vaporize the water leaving the flux intact; then gradually increase the heat until it melts. The inexperienced will soon discover that you need a surprising amount of heat to make the solder flow.

The first sign that you are nearing the required temperature is when the flux turns to a brown sticky goo; it will change from this appearance to a light-amber mobile liquid as the correct temperature is reached and it will seem to crawl all over the surface of the metal.

When you are sure the right temperature has been reached then move the flame away from the work and just touch the silver solder rod to the joint, it should immediately melt and flash around - if it doesn't then the work is not hot enough. On NO account should you have the silver solder rod poking into the flame whilst you are applying heat, not only is it likely to melt and a blob will fall off and stick just where you don't want it, but you are likely to end up with an un-sound joint through lack of heat even when it appears to flow. It is the hot metal that should melt the solder.

Tip:

With fine solder wire, if you snip a length off and wrap it round a joint before heating, but if you do this put the solder on first and cover it well with flux, then heat the work indirectly - i.e., don't blast the flame at the silver solder but to one side of the joint. When it's hot enough the solder will melt and flow normally.