Disolving disintegrated foam - Page 1
Forum section: electronics / beginners

author: tkamiya
author_rank: Super Contributor
timestamp: July 23, 2020, 06:54:01 pm
content: I bought lots of PCB mount BNC connectors on eBay with some "shelf wear".Apparently, these connectors has been stored in box lined with foam, and foam turned into a sticky goo. I've brushed off as much as I can but some are stuck to the metallic body. Would it harm anything if I soaked it in 99.x $ Isopropil alcohol to dissolve them?, then wash they dry them off?(yes, I will do it outside, away from flame, and dispose the remaining responsibly)

author: Benta
author_rank: Super Contributor
timestamp: July 23, 2020, 06:56:37 pm
content: If it's normal white styropor, acetone is the way to go. IPA won't work.

author: tkamiya
author_rank: Super Contributor
timestamp: July 23, 2020, 07:12:03 pm
content: Hi!It's black foam. I was getting more details and you beat me to it. Connector is Amphenol brand. Using alcohol pad, I can remove the stickiness and foam. But what I'm concerned with is damaging dialectic. I don't have data on what the material maybe, nor do I have the exact model number of the connector. Attaching photo for your reference.

author: tkamiya
author_rank: Super Contributor
timestamp: July 23, 2020, 07:27:24 pm
content: The dialectic is likely PolypropyleneModel number is likely31-5640-1010https://www.hmcpolymers.com/uploads/files/resources/hmc-pp-chemical-resistance.PDFsays 100% compatible with negligible effect.

author: james_s
author_rank: Super Contributor
timestamp: July 23, 2020, 07:48:45 pm
content: I'd try acetone. Try soaking one of them and see if it affects it. If it does cause any harm, you've only sacrificed one.

author: jogri
author_rank: Frequent Contributor
timestamp: July 23, 2020, 08:37:40 pm
content: Acetone and IPA won't work, try cooking it in benzene/toluene/xylene. But tbh, you are kinda out of luck as polypropylene is rather resistant against chemicals, so i would suggest using other methods like a ultrasonic cleaner or heating it to disintegrate the plastic (that might kill the insulator in the connector).

author: tkamiya
author_rank: Super Contributor
timestamp: July 23, 2020, 08:43:54 pm
content: Not having acetain handy, I tried Isopropyl alcohol anyway. I sampled with one first to make sure it didn't do damage and some of it came off. Testing was done with lower concentration alcohol.Then I went ahead and washed them all with 99.x%. It actually worked. I had to agitate well and make use of soft brush for some mechanical removal. It didn't dissolve the foam but it loosened those particles from the connector (I guess glue dissolved?). Water wash followed and blow dried the rest.Thanks for all for help.

author: tooki
author_rank: Super Contributor
timestamp: July 25, 2020, 12:29:03 am
content: Quote from: jogri on July 23, 2020, 08:37:40 pmThey said thedielectric(the insulator) is polypropylene, not the disintegrated foam!PP’s chemical resistance is an asset here, not a liability.

author: tooki
author_rank: Super Contributor
timestamp: July 25, 2020, 12:31:42 am
content: Quote from: Benta on July 23, 2020, 06:56:37 pmFYI, that’s generally called “styrofoam” in English. (The styropor name isn’t really well known in English.)

author: rdl
author_rank: Super Contributor
timestamp: July 25, 2020, 06:01:28 am
content: Styrofoam is actually a trademarked name for a specific product made from polystyrene foam, but like "Kleenex" it's pretty much become a generic catch-all name, at least in the US.

author: anvoice
author_rank: Frequent Contributor
timestamp: July 25, 2020, 06:34:52 am
content: Acetone eats styrofoam for breakfast, and polypropylene will be perfectly safe as it is a long-chain nonpolar hydrocarbon (acetone is decidedly polar).

author: tkamiya
author_rank: Super Contributor
timestamp: July 25, 2020, 04:42:11 pm
content: Thanks all, I got the job done.

author: tooki
author_rank: Super Contributor
timestamp: July 25, 2020, 07:14:19 pm
content: Quote from: rdl on July 25, 2020, 06:01:28 amIndeed! What’s amusing is that the actual StyrofoamTMproduct isn’t even the same thing as people generally mean by styrofoamnon-TM!!

author: dbctronic
author_rank: Regular Contributor
timestamp: July 25, 2020, 08:19:42 pm
content: Ah, a little late with this I know, but a lot of foam these days, notably packing peanuts, is made of starch. Detergent water would work if that's the case. If it's black, it's got carbon added to make it antistatic, although connectors hardly need antistatic protection. If it's pretty rigid and dry feeling, no gloss at all, it might be starch. Plastic foams tend to feel slick, be rubbery, and possibly have some gloss.I can't imagine what would make plastic foam on stored components turn to goo except serious overheating, which polypropylene wouldn't like either. Your failed adventures with powerful solvents rule them out as causes. I've tried gluing polystyrene foam with plastic model glue, and I can assure you that a tiny bit of toluene collapses an amazing mass of polystyrene foam in two seconds, then disappears and leaves a rock hard mass.On the other hand, starch would degrade simply by getting damp.

author: tooki
author_rank: Super Contributor
timestamp: July 25, 2020, 08:50:25 pm
content: Quote from: dbctronic on July 25, 2020, 08:19:42 pmJust age. Many foams turn to dust after a few decades. It’s very common in old electronics, both in finished goods and in component packaging.

author: mikerj
author_rank: Super Contributor
timestamp: July 25, 2020, 10:01:50 pm
content: Quote from: tooki on July 25, 2020, 08:50:25 pmAnd speaker surrounds!

author: rdl
author_rank: Super Contributor
timestamp: July 25, 2020, 10:35:32 pm
content: A lot of things have a so called "rubberized", or "soft touch" coating applied which eventually turns to sticky goo. This is because they don't use real rubber and instead it's some cheap thermoplastic elastomer crap that only lasts a few years before it fails. I really wish they'd just stop using that garbage.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 25, 2020, 10:36:44 pm
content: Quote from: tooki on July 25, 2020, 12:31:42 amIn Brasil the name is Isopor, which is also a trademark but from Basf. You call it anything different and nobody will have the slightest idea what you are talking about.Another one is Hydrogen Peroxide - everybody there calls it "oxygenated water" (água oxigenada).

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2020, 12:33:06 pm
content: Quote from: rsjsouza on July 25, 2020, 10:36:44 pmIn Spanish, too! My dad is Latin American (and a doctor) so I learned “agua oxigenada” as a kid!Meanwhile, here in Switzerland, practically nobody uses it for wound care. When I first moved here, before I knew very much German, I went to a pharmacy to get some and I didn’t know the word. I asked the pharmacist “maybe in English? It’s ‘hydrogen peroxide’” but that didn’t work, either. So then 12 year old me says “ummm, H2O2?” and that finally got us on the same page.And I still had to convince her it was for wound care and small blood stain cleanup and not for nefarious purposes! :p But at least I did learn the German word for it: Wasserstoffperoxid!

author: tkamiya
author_rank: Super Contributor
timestamp: July 26, 2020, 04:08:50 pm
content: Haha.... I did the same thing. Being born in Japan first, I knew little of English back then. I used to use Chemical formula instead of name.Oxygenated Water refers to water infused with water here in United States. These are sold in grocery stores as "health" products. Distinctly different products from H2O2