..such as crevices, common plumbing flux and though I've experienced luck with most solders, four% silver bearing solder is more powerful Eventually...kinda costly tho... I had Harris solder on hand at the time so no significant deal for me but costly if you do not have to have the strength https://types-of-automotive-hose05936.creacionblog.com/27168553/rumored-buzz-on-types-of-solder-to-use-on-aluminum-radiator