Would this fall under the category of oxidation? - Page 1
Forum section: electronics / repair

author: elroy
author_rank: Regular Contributor
timestamp: November 30, 2022, 01:49:01 am
content: A threaded power connector on a 1960s-vintage piece of gear. Would this fall under the category of oxidation? Any suggestions on best cleaning product or method? I have plentiful DeoxIt, but didn't know if that would be the way to go.

author: Haenk
author_rank: Super Contributor
timestamp: November 30, 2022, 05:40:08 am
content: There usually is a zinc based coating on the screws, the metal part of the connector is mainly made from zinc, too.Unfortunately, zinc and moisture is not a great combination.I'd say replace the screws and brush off the connector, maybe use a bit of mild vinegar.

author: coppercone2
author_rank: Super Contributor
timestamp: November 30, 2022, 06:08:40 am
content: i don't know if you want a power connector that dodgy.. if you really want to try, do the vinegar soak and cut ultra fine scotch brite pad into long strips that you can pull along the threads back and forth to clean that up. IMO a brush is going to do damage. But power connectors I do not restore (or anything that pulls current).

author: SeanB
author_rank: Super Contributor
timestamp: November 30, 2022, 09:12:01 am
content: Simplest fix is to take a new toothbrush, and soak the bristles with WD40, and scrub the threads, and then rinse off with more, and wipe clean with a paper wipe. That will get most of the corrosion off, and the same for all those screw heads to remove the corrosion gently. Inside a earbud with WD40 works as well, though you will need to use a few till they come out clean. Leaving the thin coat of WD40 will protect it for a while, as the coating, likely a cadmium plate, is degraded. Note all the items you use to clean can be classed as hazardous waste, so put in a plastic bag, seal up, and put in the right disposal for your area, either in the regular garbage or in ewaste disposal.

author: jpanhalt
author_rank: Super Contributor
timestamp: November 30, 2022, 10:06:02 am
content: Quote from: elroy on November 30, 2022, 01:49:01 amYes, it's oxidation. I don't know of any true metal (i.e., excluding metalloids*) that can have a valence less than 0, i.e., that can be reduced beyond its metallic state. Thus, what you show is oxidation. Most metal oxides are alkaline (e.g., NaOH) and so might be removed by dilute acid (e.g., vinegar). Some are amphoteric (e.g., aluminum) and react with both acid and base. Physical removal is pretty effective. I have never used Deoxit, but it's worth a try. Lubricants like WD-40 may help. Electrolysis can also be used, but will probably leave a pitted and dull surface.*Metalloids, like tellurium, can have a negative valence.

author: Gyro
author_rank: Super Contributor
timestamp: November 30, 2022, 11:24:44 am
content: Trying not to sound like a stuck record, a good dollop of Vaselline on the threads and working the connector sleeve a few times would have been a standard solution back in the day. It's preservative, lubricant and moisture protection.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 30, 2022, 11:46:52 am
content: Quote from: jpanhalt on November 30, 2022, 10:06:02 amSeveral can, but under exceptional conditions (soaked in pressurized carbon monoxide or worse chemicals), or certain combinations you're never going to encounter (e.g. cesium auride).Anyway, what's pictured looks mostly superficial, you'll have to inspect a bit to see if it's deeper, pitted, cracked or otherwise compromised. If the latter, replacement is necessary; on the upside, circular MIL connectors like that never went out of style, but, neither did their prices.So yeah, wire brushing to remove crust, a lubricant helps (not WD40, it's not a lubricant!).I don't think contact cleaner helps particularly on bulk metal parts? It might not hurt. Definitely for the contacts, if nothing else.If the parts aren't plated they can perhaps be soaked in acid or base, or complexing agents, anything that dissolves the oxides -- but be careful, this can be quite aggressive, leaving to a rough (matte) finish, and further corrosion as the chemicals are almost impossible to remove from microscopic pores in the metal (let alone gaps between plastic parts, if you can't completely disassemble them). More of a last resort, or an option on bulk pieces that you can further treat the surface of (so, mostly fine for, like, car parts, weldments, etc.). And needless to say this likely ruins any plating: zinc dissolves readily in acid, nickel not so much but pitting will lead to undercutting and ideally the part would be stripped and replated, assuming it was worthwhile to do so in the first place.Compromised integrity can happen to certain alloys; aluminum, bronze and steel are pretty good for the most part, corroding mostly from the surface, give or take pitting. Zinc alloys are the most common exception, as a minute lead impurity leads to eventual destruction (the material crumbles apart). This mostly affects very old (pre war?) potmetal parts, before they were aware of this catalytic role or something like that; later parts should be pure enough not to be affected, but if not (bad batch?), it's always a possibility.Oh, beware of cadmium plating, quite toxic especially to kidneys. Usually apparent as an otherwise fairly shiny metal surface, somewhat darker than steel, with greenish to yellow dusty corrosion on it. Use water to wash/scrub it off, prevent it from emitting airborne dust.Tim

author: abdulbadii
author_rank: Frequent Contributor
timestamp: November 30, 2022, 11:47:22 am
content: White rustIt is a white powdery deposit formed from a natural corrosion process that can occur on any new zinc coated steel product

author: elroy
author_rank: Regular Contributor
timestamp: November 30, 2022, 04:21:28 pm
content: Thanks for all the comments.What got my attention the most was the mention of cadmium plating being likely, with that element being super toxic. It sounds like cadmium plating is still standard in many applications, so I gather it's safe when undegraded, but possibly a problem if it corrodes? Airborne dust would be the usual exposure path? Any reason to use, say, gloves other than nitrile or vinyl while working on it?I also have the mating plug connector (below) to work on. I'm told that replacements for both are available locally. Not clear if those would be salvaged vs new-old stock vs current-day new, or if any of that would make a difference (besides avoiding corroded salvaged pieces).I can see the benefit of replacing rather than restoring for power connectors, though the power consumption is low in this case -- said to be about 5 watts.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 30, 2022, 05:09:28 pm
content: White corrosion suggests aluminum or zinc, not a problem here. Cadmium, I think cutaneous of dry stuff doesn't matter, just wash up after handling. Gloves aren't a bad idea, sure. Inhalation/ingestion is the main likely hazard. If in doubt, check for handling safety guides.Tim

author: elroy
author_rank: Regular Contributor
timestamp: November 30, 2022, 10:14:15 pm
content: Thanks. On a cosmetic front, the person who sold this to me gave the knobs a wipe, but didn't really clean the entire front panel. Is window cleaner a pretty safe bet for 1960s-era painted metal? Or anything better to try?

author: coppercone2
author_rank: Super Contributor
timestamp: December 01, 2022, 03:02:48 am
content: I use simple green on the front panel of HP stuff from the same time period, sometimes in a ultrasonic, I never had a problem, but it never looked too good anyway because it was usually scratched up. Usually use a nylon dish brush (the kitchen kind) and then follow it up with the non abrasive blue kitchen scotch brite (its just woven plastic) if required in certain spots, then go to more advanced cleaners if there are still problems (for spot cleaning). I never saw paint flake off. Just be careful on the crappy lettering, like if its just ink to mark say screw terminals, but the front panel ink is fine. For some reason the lettering for screw terminals is always trash compared to the lettering near ports and switches.Knobs IMO go best in a hot ultrasonic cleaner followed up by brush & rinse with a smaller brush like a tooth brush.

author: iJoseph2
author_rank: Regular Contributor
timestamp: December 01, 2022, 01:32:30 pm
content: Quote from: T3sl4co1l on November 30, 2022, 11:46:52 amWow, I never expected connectors to be cadmium plated.When I received my Racal-Dana 2101 frequency counter a while back, the input connectors (maybe it was just the n type connector) had some green corrosion on it. I think I cleaned up the connectors with IPA on a cotton bud as best as possible then put a cheap Chinese SMA adaptor on it. Mine even has the M (military) option so maybe it could be cadmium plated.Not my photo but it looks like this...https://www.sglabs.it/en/product.php?s=racal-dana-2101&id=1613

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 01, 2022, 09:41:56 pm
content: Could also be chrome, but not usually on electrical connectors I would think/hope(??!). Chrome you sometimes see corroding on bathroom fixtures, it has a deeper forest-green hue, sometimes dusty, sometimes spots (pinholes/pits).Certainly shouldn't be anything newish with it, it's been out of vogue for a long time, MIL spec aside maybe, at least I think.Tim

author: iJoseph2
author_rank: Regular Contributor
timestamp: December 03, 2022, 11:37:15 am
content: Quote from: T3sl4co1l on December 01, 2022, 09:41:56 pmThanks for the update!I went through some old photos and found some snaps I took of it as received.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 03, 2022, 01:54:43 pm
content: Doesn't look very green, maybe the photos don't capture it but just looks dusty.Tim

author: iJoseph2
author_rank: Regular Contributor
timestamp: December 03, 2022, 03:15:03 pm
content: Yeah, looking back at the photos there's hardly anything there.You can just about make out something on the outside of Input A right at the back of the BNC. And a couple of spots on the bottom part of the inside of Input B.The Input C N connector looks clear to me so I obviously misremembered.But like you say looks more like dust.Thanks!

author: coppercone2
author_rank: Super Contributor
timestamp: December 03, 2022, 04:02:59 pm
content: that one I can see rubbing with a q-tip with deoxit could help a little, but the OP picture is no beuno.