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SIF SILVER SOLDER NO 39Cadmium Free silver solder is suitable for use on all ferrous and non-ferrous metals, except aluminium. It can be used with a range of heat sources. Use SIF SILVER SOLDER flux.SIF SILVER SOLDER No 40A popular grade of Silver Solder offering good capillary action and ductility in many ferrous and non-ferrous applications. Use with SIF SILVER SOLDER flux.SIF SILVER SOLDER No 43Cadmium Free 55% Silver Solder, which is free flowing and ideal for close-fitting capillary joints and for a colour match on stainless. Use with SIF SILVER SOLDER flux.SIF SILVERCOTE No 43Cadmium Free Silver Solder No 43 with full flux coating.
Straight answers to the questions people ask most when choosing and using silver brazing rods and wire.
It tells you roughly what sort of alloy it is. Silver brazing alloys range from fairly low to high silver content, and the balance is mainly copper and zinc, sometimes with a little tin or nickel. The silver content affects colour, melting range and how freely the filler flows.As a general guide, higher silver alloys are whiter and tend to run at lower temperatures and flow more freely into tight joints, while lower silver alloys look more yellow, like brass. The exact melting range and best joint gap are different for every alloy, so read the maker's data sheet rather than relying on the percentage alone.
They are classification codes from the international standard for brazing filler metals. Each code identifies a defined alloy composition, so two products carrying the same code should have the same make-up even if they are sold under different names. Older standards used different codes, and some products list both.The code helps you compare alloys and check that a replacement matches the one in your procedure. It does not tell you the diameter, whether the rod is flux coated or the pack size, so check those separately on the product details.
Older silver brazing alloys often contained cadmium, which gives off highly toxic cadmium oxide fume when it is heated, and overheating makes this worse. The HSE has guidance for people using cadmium-containing brazing products, and serious illness has been recorded after exposure to the fume.Cadmium-free alloys remove that particular hazard and are the usual choice today. You still need good ventilation or local extraction for the flux and metal oxide fume, and you should be careful with any cadmium plating on the parts, which should be dealt with before heating. Follow the maker's safety data sheet and your risk assessment.
Yes, unless the rod already carries a flux coating. Flux removes the surface oxides that form as the metal heats and keeps the surface clean until the filler has flowed. It does not remove oil, paint or grease, so the parts must be cleaned first.The flux has to be active before the filler melts and remain active until the joint has solidified. If the heating cycle is long, the flux can wear out, so use a flux suited to the temperature range and the parent metals. Silver brazing fluxes are not suitable for aluminium.
Bare rod is used with flux applied separately, as a paste or powder mixed with water, which lets you place the flux exactly where it is needed and choose a flux to suit the job. Flux-coated rod carries the flux on the outside, so you do not have to apply it by hand, which is convenient for site and repair work and for awkward positions.The coating suits many jobs, but where you need a specific type of flux, such as for stainless steel or long heating cycles, bare rod with a chosen flux is often the better route. Check the maker's data sheet for the flux type.
Very small. Silver brazing relies on capillary action, which draws the molten filler into a narrow gap, so the parts should fit closely with only a fraction of a millimetre between them. Too wide a gap weakens the joint and can leave voids, while no gap at all stops the filler entering.The best gap is the one at brazing temperature, not room temperature, and it changes if the two metals expand at different rates. The maker's data sheet gives the recommended gap for each alloy, so use that figure.