I think a wrinkle is being missed! It's the difference between heat and temperature.

Your iron can do temperature (centigrade) , but not produce enough heat (watts).

Aluminium is an extremely good conductor of heat and wrapping a length of Ali wire around an electric soldering iron is probably removing heat faster than a small electric iron can supply it. In the same way, a coal fire burning 900°C hotter than the melting point of Copper doesn't melt a boiler full of water because the water absorbs the heat.

Try cutting 15mm of the solder off and holding it in an insulating wooden peg. The iron might have enough grunt to melt it. But I think you need a more powerful heat source such as a blowlamp, or an old-fashioned soldering iron – the type with a hefty copper tip that was heated on a kind of gas ring. The solder is probably OK.

Dave

What's the name of the two solders, Robin, and what do they claim on the tin?

I have two kinds of aluminium solder, one low temperature one [Durafix], and one high temp. [580C].

They both work as expected. The second kind gives what appears to be a stronger bond, but more care is needed when soldering because the melting point of the parent metal is not much higher than that of the solder.

Chronos sell Durafix Easyweld and their page has a video with a chap showing how it's used. He uses a medium sized torch and heats the job until the end of a solder rod dabbed on it flows. The rod isn't heated directly, he shows it blobs if you do. As always, the expert makes it look easy, but I expect it needs practice.

Can you report back how Easyweld compares with what you've got? I doubt the existing stuff has a quality issue because there isn't much to go wrong with the rods. All they have to do is melt at the advertised temperature. There's no flux. But it's essential the torch be powerful enough to get the area around the weld hot enough.

Dave

I might, at this stage, remind myself that most failures I have had have been down to me, not the tools. I don’t generally blame the tools – unless they are sub-standard (usually because they were cheap, diy-er ‘use once and throw away’ chinese tools).

Perhaps Robin needs to partake in a bit of reflection? I bought a long length at the last Midlands Exhibition. Worked a treat, with a little practice – and I am likely going to buy some more shortly.

I have repaired several items with those rods with complete success. I right now have a job to repair 2 riding mower, mower deck gearboxes. They have a 1 5/8" bearing adjusting nut with a hidden locking setscrew. No one including Me seems to find it and ham hands the bearing nut off. The ID of the bearing bore needs built up and rethreaded. Will have to be getting on with the job and will try to get pictures.

There used to be a guy at Rufforth autojumble who was doing live shows with the stuff.

I used it once on my Son's alloy sump off a Clio sport. It had spider web crack after he hit a brick in the road going down the M1. Very successful repair. It always said make sure you brush the area with the supplied wire brush. Which i suspect was stainless steel.

Steve.