SV: [sdiy] Solder won't stick to old PCB

[cheater cheater]

toothpaste is a very strong base. It is alkaline and, if it reacts
with the oxides on metal, could leave salt (?) residues on the
surface. to remove oxides you need a reducing agent, such as an acid.

The eraser idea is very good imo.. haven't tried it myself, but I
heard it's good for reconditioning faders / pots

D.

On Sun, Sep 27, 2009 at 9:19 PM, John Alex Hvidlykke <john at hvidlykke.dk> wrote:
> Well, one of the most effective cures for tarnished silver (but probably not
> as good a The Dip) is regular toothpaste. Might as well try that on my
> oxidised component leads ;-)
>
> \John
>
>> -----Oprindelig meddelelse-----
>> Fra: synth-diy-bounces at dropmix.xs4all.nl
>> [mailto:synth-diy-bounces at dropmix.xs4all.nl]Pa vegne af David G. Dixon
>> Sendt: 27. september 2009 22:04
>> Til: 'Graham Atkins'; 'John Alex Hvidlykke'
>> Cc: 'Synth DIY'
>> Emne: RE: SV: [sdiy] Solder won't stick to old PCB
>>
>>
>> They used to sell this stuff for de-tarnishing silverware the easy way,
>> where you just dip the silver into this solution and it comes out
>> perfectly
>> shiny.  I think it might have been called "Dip-It".  I think that
>> infomercial guy who just died (Billy something-or-other) was hawking
>> something similar on TV recently.  I don't know what this stuff
>> is, but I'm
>> guessing it's some sort of reducing agent (sodium borohydride, perhaps?).
>> When I was a kid, I used it on bronze coins, and it worked perfectly.  I
>> think one could brush this stuff on oxidized copper traces/pads
>> to the same
>> effect.
>>
>> > Before now with badly corroded joints I've used a mildly abrasive
>> > paste like
>> > T Cut (For car paintwork) applied on a cotton bud, but clean well
>> > afterwards.
>>
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