The information provided includes the basic rules for obtaining good brazing, rules that must be observed if the maximum benefit is to be derived from silver alloys.

Careful observance of these rules allows to reach a high level of efficiency in brazing and to minimize any possible risks that could derive from a bad use of alloys and fluxes.

Rule No. 1 - USE ONLY CLEAN PARTS

All metals must be clean and free of any form of contamination such as scale, dirt, oil, grease, etc. Failure to observe this precaution will make the joints unstable and cause unpleasant smoke emissions.

Plated components should be treated with care.

Rule No. 2 - CHOOSE A SUITABLE ALLOY AND DEOXIDANT

Select the correct combination of alloy and flux (if required), referring to the table in the catalogue.

Never use a low melting range alloy in conjunction with a high melting range flux and vice versa.

Rule No. 3 - ALWAYS USE AN ADEQUATE QUANTITY OF DEOXIDANT

Not only is it important to choose the appropriate flux, it is also essential that a sufficient amount is used as a protection of the joint area throughout the duration of the brazing cycle.

As a general rule, too much flux is better than too little. If the flux runs out, the flowability of the alloy is limited, and there is a danger that the alloy not protected by the flux will volatise, causing smoke.

Rule No. 4 - HEAT EVENLY

The purpose of brazing is to heat the parts to be joined to a temperature 50°C above the melting point of the alloy, allowing the alloy to flow into or along the edges of the joint.

Use a flame, heat the joint area generally by focusing on the heavier sections, always focus on the joint and never make attempts to melt the alloy by heating it directly with the flame.

The alloy should only be applied when the joint reaches the right temperature (the flux acts as a pyrometer, when it liquefies like water it indicates the bonding temperature).

Overheating is bad practice. Not only can it lead to poorly-brazed joints, but there can also be harmful smoke emissions from both the flux and the alloy.

Rule No. 5 - MAKE SURE THAT THERE IS SUFFICIENT VENTILATION

Under no circumstances should brazing be carried out in confined spaces or in precarious ventilation conditions.

Rule No. 6 - ASK FOR ADVICE IF YOU NOTICE SOMETHING ABNORMAL

If any abnormal effects occur during brazing, such as copious fumes, or any kind of difficulty in applying brazing materials, stop immediately and seek advice.

Just because you don't feel any harmful effects doesn't necessarily mean you're at risk.

PRECAUTIONS

Alloys containing zinc and cadmium can, if used under abnormal conditions, cause emissions of gases which, if inhaled, are harmful to health.

In the case of zinc, the effect can be unpleasant, but temporary, while the emission of cadmium fumes is poisonous and in many cases has proven fatal.

There can be emissions if these alloys are:

1. used without deoxidiser;
   
2. used with the wrong type of flux;
   
3. used with a bad flux;
   
4. overheat above their normal melting points;
   
5. used on dirty metals.
   

These considerations can be applied to fluxes which, if heated above their normal working temperature, lose their characteristics (fluidity, activity, life) giving rise to irritating emanations of gases that must not be inhaled.

Particular care must be taken in handling fluxes which can sometimes irritate sensitive skin. The use of gloves or protective creams is recommended before brazing.

Since low melting fluxes contain fluorine-based compounds, they are classified as poisonous, they should never be ingested. It must be emphasised that alloys and fluxes can be used safely with the observance of these basic precautions.

Silver-copper-zinc-cadmium alloys have been used for more than 40 years in a wide range of applications.