solder

I don't know the answer to your question but, if you have a Toolstation nearby, their product 81552 might (expensively) meet your 60/40 spec.

HTH

Nick

Think most plumber's merchants still stock leaded. For non potable use.

It should, at least in theory.

At the risk of teaching you to suck eggs, you've got a couple of things stacked against you. Soldering a corroded (rusty) surface, one that is oily, and a vessel/tank.

Give the area a good clean with some degreaser, then some emery cloth or similar, degrease again. Make sure the tank is open- you don't want the heat used to solder to cause the air inside to expand an try and escape via your joint/patch.

Tin the area, and the patch, flux both, place the patch in position and heat. You may need a bit more solder but, hopefully, the patch will 'pull' into position (or nudge it) as the solder melts. Don't disturb until it is cool, lead free is a s*d for 'dry joints' if moved while cooling.

I'd be tempted, if the hole is small, to try and pull a bolt through with a cotton thread. Place a nut on the outside, tighten, hold the bolt thread with pliers, then solder over it. Clean the area first, as before. I saw this done once, the chap used a wire through the hole to tie the cotton to via the filler hole.

I was once introduced to a car body repairer; he was: "George, the only person I know who can weld two pieces of rust together.

It's the flux that determines wetting or not. I'd reach for killed spirits for that job, but rosin can do it. Or you can try plumbing flux eg Laco.

NT

Thanks Nick, Toolstation here closed last week and I was after plain solder as I will use a powder flux, after I clean it with a wire brush and spirit of salts aka brick cleaner.

AJH

I hate modern solder. Now of course I can no longer see to do it, but this new stuff actually smells worse than the lead stuff, probably different flux, and also seems to be far less good at actually soldering stuff. Bah humbug. Brian

brazing is more likely to last.

flux and brass wire or silver solder if you don't have a powerful enough torch to heat it.

If you are talking electronics, no reason at all not to use 60/40 multicore. All the big suppliers like CPC sell it - and you're unlikely to be able to buy any electronics solder in a high street shop now anyway.

Aldi

You have to go with your mum, sign a disclaimer and promise not to heat it above ambient.

AB

You have a Toolstation on your High Street? ;-)

Sadly no!

The nearest high st is 30km away.

We have a Screwfix in Derry though, a mere seven hours drive.

AB

That turned out to be the solution, small plumbers merchant down the road, actually the nearest shop had a 1/2 kilo roll under the counter.

Once I had wire brushed the rust off there were 3 small holes I could just put a sewing needle through, Baker's No3 flux and they were easily wetted and filled, so far a bit less than successful in floating a cover plate over the lot, not that that's really necessary with a thick layer of solder.

In the past I would have simply brazed without cleaning the rust as the flux and acetylene flame work at red heat but I gave up my oxy-acetylene when I retired, I have been tempted to try TIG with braze but I haven't pursued it as I seemed to use too much argon.

AJH

Gasless wire MIG is a joy to use. I 'grew up' on arc & to a lesser extent oxy.

I always wondered if one could use CO2 or even flame fumes in lieu of argon, I presume not.

Leaded solder is still used in electronics, just less so. Handy for large non-potable plumbing joints that are a pain to heat.

NT

Any experience of Aldi/ Lidle el Cheapo welders?

I have a couple and tried to use one a few months back with zero success.

Not sure if what I was trying to do was practical i.e replage a damaged M5 threaded rod on a stove glass holding clip.

AB

You're a better man than me if you can repair a rusty fuel tank that way, though.

At least with an inverter stick welder I can *sometimes* fix the holes that I have made in sheet metal.

Yes, I have both a gasless MIG and an inverter stick welder and I find the inverter welder much easier to use for most things. Though I guess for really thin stuff the MIG might win.