lead free soft soldering

[emptybucketman]

I've done a little silver soldering with copper pipes and fittings using MAPP gas with success. I thought I'd have a go with the lead free (tin) soft soldering, however, I can't get the solder to flow into the joint and it just rolls off the pipe. Do I need a special lead free soft solder flux and how much heat should I apply?...I get the joint glowing.

[DJ’s Timber]

Two things straight off.

Yes you need flux

and

if the joint is glowing, it's too hot and you will end up burning the solder

[emptybucketman]

Thanks DJ, How do you know when you've applied enough heat using a MAPP gas torch?

[DJ’s Timber]

Every now and then remove the flame and touch solder to copper and see if it melts the solder. You don't need a lot of heat, solder doesn't like high heat as it will get brittle.

Generally I just heat till it just starts to run and keep the flame away till heat starts dieing and reheat till just starts running again

[journeyman Mick]

Oh, and don't trust soft solder for copper pipes carrying water where the joins will be concealed when finished.

Mick

[wonderplumb]

Why waste your time with soft solder when you can silver solder? Much better job and wont break like soft solder does.