Help required

It does, don't ask how I know.

Easyflow is about 620deg, Cad free 55% is 630-660deg. Melting point of aluminium 660deg so there is not much leaway.

J

I doubt the aluminium would melt at silver soldering temperatures.

regards David

Sorry, that is not correct, alum will melt at the high end of silver solder temps, especially small sections of alum.

JD

Hi,

There are various 'resists' to prevent flux and hence silver solder flowing. A I showed the OP Tippex works well (as Jason shows) also lead pencil (graphite) as well as a past of jewellers rouge and even loam will work. The main job of the resists is to prevent the flux spreading and there is no flux the solder will not flow. More than one way to skin a cat!

Best regards

T

Thanks all

Tippex and lead pencil it is then.

I guess this could be one instance of Tippex correcting mistakes BEFORE they occur!

Cheers

Norman

By definition, the brazing process, of which silver soldering is a part, is carried out above the melting temperture of aluminium.

Soldering is carried out below the melting point of alumnium.

For an explaination of this fact find an appropriate historian!

As above, silver solder (silver brazing alloy) will not flow/adhere to tippex residues, graphite, or stainless steel if you use a flux unsuitable for brazing. eg the conventional low temp flux

Unless you use a specfic flux for soldering alumnium, then soft solder eg 60/40 tin/lead, 97/3 tin/copper, comsol will not adhere to aluminium

regards

keith

Sorry to contradict the expert, but electricians solder can be made to adhere to aluminium sheet. Clean a patch with abrasive, cover it with a light oil (e.g. 3 in 1) heat it with a big soldering bit and melt a pool of solder into the hot oil. Use tip of iron (if iron clad over copper) or use a steel point to scratch at the aluminium if the solder is reluctant to bond.

Try it, you will be surprised how readily you can tin aluminium this way, as long as you can get enough heat into it without the oil catching light!

I've done this to make an earth connection to an aluminium box.

Neil

Sorry Neil, it is not a true contradiction, Keith said, unless you use a specific flux, flux deoxidises the surface and keeps the oxygen away.

What are you doing,? Spreading an oil = keeps the oxygen away, scratching the surface = removing the existing oxides, hence some form of adhesion/bonding.

Neil, been there done that, soldering earth wire onto radio chassis, think I found out about the method in Practical Wireless, back in the day when radio was my hobby. Ian S C

Kwil

I wouldn't call 3-in-1 a specific flux for aluminium, though you are welcome to!

Neil