Hello I have a eico stereo 40 that has a very tarnished selector switch. I tried caig deoxit and it's not removing the black tarnish what else could be used maybe Brasso?
I use an equivalent to this stuff https://www.homedepot.com/p/Tarn-X-12-oz-Tarn-X-Tarnish-Remover-TX-6/202523464, its a nasty chemical though, thiourea.
Rinse off after its done and then dexoit or switch lube of choice...
Rinse off after its done and then dexoit or switch lube of choice...
Leave it alone if it is working!!! Silver oxide is black and is still a good conductor. Silver sulphate tends to brown and is not a good conductor. Using something meant to clean silverware bright and shiny is not a good idea for electrical contacts.
If it is possible to remove the switch apply Tarnex silver cleaner to the switch's contacts and rinse thoroughly with distilled water. Rinse several times to be sure all Tarnex residue is removed, since it's conductive. I do that and the contacts come out looking like new. After switch is dry, then apply DeOxit.
As an alternative to chemicals, I've been using a piece of melamine foam pad (aka magic eraser) with isopropanol, 90% as good as the tarn-x, tarn off, Goddards silver dip etc.
The melamine's great when switches can be disassembled while still soldered to the pcb.
melamine pads are slightly abrasive but i haven't seen any damage on metal surfaces under a microscope
Then a contact lube like RS PRO Lubricant Contact Cleaner RS Stock No.: 136-8550 this has 1H-benzotriazole, which I have a feeling is what everyone is paying through the teeth for in deoxit
Inhibition Effects of Benzotriazole for Tarnishing and Corrosion of Silver
"The inhibition effects and mechanism of benzotriazole (B.T.A.) on tarnishing and corrosion of silver were studied by means of potentiostatic polarization curves, differential capacity-electrode potential curves, and accelerated testings in H2S and SO2 atmospheres. It was recognized that B.T.A. had little inhibition effects in acidic solutions (pH 2.5), but had great effects in almost neutral solutions; because, B.T.A.-Ag complex was formed on the surface in anodic potential region, and B.T.A. was adsorbed on the surface with lone electron-pairs of N-atoms in cathodic potential region. Silver treated with B.T.A. had an enhanced resistance to tarnishing in H2S atmosphere. "
regards
james
The melamine's great when switches can be disassembled while still soldered to the pcb.
melamine pads are slightly abrasive but i haven't seen any damage on metal surfaces under a microscope
Then a contact lube like RS PRO Lubricant Contact Cleaner RS Stock No.: 136-8550 this has 1H-benzotriazole, which I have a feeling is what everyone is paying through the teeth for in deoxit
Inhibition Effects of Benzotriazole for Tarnishing and Corrosion of Silver
"The inhibition effects and mechanism of benzotriazole (B.T.A.) on tarnishing and corrosion of silver were studied by means of potentiostatic polarization curves, differential capacity-electrode potential curves, and accelerated testings in H2S and SO2 atmospheres. It was recognized that B.T.A. had little inhibition effects in acidic solutions (pH 2.5), but had great effects in almost neutral solutions; because, B.T.A.-Ag complex was formed on the surface in anodic potential region, and B.T.A. was adsorbed on the surface with lone electron-pairs of N-atoms in cathodic potential region. Silver treated with B.T.A. had an enhanced resistance to tarnishing in H2S atmosphere. "
regards
james
The brasso worked well didn't get all over the place and a small 8 ounce bottle will last me a life time. I was pretty disappointed that caig didn't do a better job for it's price. I forgot to clean the stereo reverse stereo switch so I'll be back at it today, it only took about an hour and 6 qtips to clean the selector switch.