I finally understood why my old boss in Tampa always insisted on cleaning flux with a toothbrush

Last month, I was fixing a vintage receiver and saw how the leftover residue was causing a slow short under a chip. Has anyone found a better tool for getting into those tight spots on old boards?

3 comments

3 Comments

kaigibson2mo ago

Honestly, I skip the brush most of the time. A good soak in high percentage isopropyl alcohol does the real work, then I just blast the gunk out with a squeeze bottle or an air duster. All that scrubbing can stress old solder joints. If something is really stubborn, a quick pass with a soft toothpick before the rinse is all it needs.

thomas_sanchez2mo ago

Yeah, that old flux turns conductive over time. I've seen it eat through traces on 70s gear. A stiff bristle brush with some isopropyl alcohol works, but you gotta be careful not to knock off those old jumper wires. Sometimes I use a dental pick to gently scrape in really tight corners before brushing. The real pain is under those big can capacitors.

mary_nelson712mo ago

Oh man, that toothbrush method is no joke. I mean, I had a similar mess with an old clock radio where the flux gunk actually bridged two pins on a transistor, made it act all crazy. Ended up using a cheap paintbrush with the bristles cut really short, dipped in alcohol, to kinda scrub under there. It's a pain but you can really see the difference after, like the board looks new. Still hate getting under those big metal cans though.