..which include crevices, normal plumbing flux and when I have experienced luck with most solders, four% silver bearing solder is much better In the long term...kinda highly-priced tho... I'd Harris solder on hand at time so no big deal for me but high priced if you don't require the strength https://typesofspoilers67887.bloggadores.com/26997224/a-simple-key-for-types-of-solder-to-use-on-aluminum-radiator-unveiled