WIPE off any external flux while still hot. This is easy to do but
plumbers never seem to bother. It eventually makes a green mess if you
leave it.


I got bollocked by a Corgi regd guy for wiping the joint - he was adamant
that this was a fail on a trade test if you did that (been a heating
engineer for 50+ years)
His reasons were that the solder ring should form and you should leave it at
that, if youy wipe it yopu stand the chance of wiping impurities into the
joint.


Rick