Soldering the Unsolderable

[sportster4eva]

Hi gang,
Here's the scoop. I have a bagful of old stock CTS pots that I've had for a while. They have started to accumulate a sort of "patina" on the lugs. It's a blackish tarnish, and almost looks like what you see on silverware.. Well, I can't for the life of me get solder to stick to the stupid things. I took a wire brush to them, nada, hit them with some fine sandpaper, same...
They are clean and shiny now, but will not take solder. I'm using a Weller temp. controlled station and Kester 63/37.
I was thinking of dipping them in a little Ferric Chloride for a sec, or maybe plumbers flux.. Has anyone had this situation, and were you able to straighten it out? I'd rather not throw out 20 new/old pots if I don't have to.
Thanks!

[Structo]

Have you tried rosin flux?

I wouldn't use plumbers flux since that is acid based.

Pretty weird that after sanding they wouldn't clean up good enough to solder to.

How about Tarnex or some other chemical cleaner?

[sportster4eva]

I agree, it's strange.. I am using rosin core solder. I was skeptical about the acid flux myself. I'm not giving up though.

[selloutrr]

I've had luck with a quick blast of love on the dremel. followed by a hot 700 degree weller iron and kester 60/40 .33. FLOOD the tabs with the solder. Let it cool down for awhile ( 30 min ) come back and suck the solder off you should be tinned and good to go for any project.

[Andy Le Blanc]

remove the gundge any way that works, I did a quiky this morning with an
old gretch playboy wah, even the bare wire after striping was stuborn with
oxide, had use a dab of automotive connector/electrical cleaner, dont know why it
worked where other stuff didnt, try fine grit wetdry paper with any electronic
cleaner.

[novosibir]

Dimp the contacts into silver cleaner fluid for a few seconds and then wipe it off w/ a paper towel. Sanding removes the galvanic coating and the basic metal doesn't solder very well.

Larry

[butwhatif]

a few swipes with the old steel solder brush is fast and works wonders Mouser 384-1018