Anyone know if "J B Weld" epoxy conducts electricity? - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: October 01, 2021, 04:00:00 pm
content: This stuff:https://www.jbweld.com/product/j-b-weld-twin-tubeDo we know if this stuff is conductive after it's fully cured? Thanks...

author: iRepairElectronics
author_rank: Contributor
timestamp: October 01, 2021, 05:13:25 pm
content: I imagine so. I have picked it up with a magnet before. dont know what the conductivity is.

author: Ian.M
author_rank: Super Contributor
timestamp: October 01, 2021, 05:32:10 pm
content: I believe in bulk its fairly non-conductive, as for the epoxy to flow out the tube, it must have excess resin over that required to fill the interstitial space that would exist if the steel particles were close packed, so there tends to be an epoxy film between steel particles, but its unsuitable for use as an insulator as there is a risk of locally conductive pathways forming through it.

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 02, 2021, 04:49:59 am
content: It's not specifically conductive, but that's not to say it can't be, it is metal filled after all.It's more capacitive than anything, but I would avoid using it near any conductors to be safe.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 02, 2021, 04:54:23 am
content: When I have poke probes at it (spaced multiple cm apart) it has read open to the limits of the DMM. But Murphy says that it really matters a conductive path will show up. I certainly doubt that its dielectric strength is high.

author: jfiresto
author_rank: Frequent Contributor
timestamp: October 02, 2021, 07:38:02 am
content: Indeed. As an experiment, you could pot a connector with steel-filled epoxy, measure an open between the terminals and then have to apply 230VAC for a few days before it begins to arc internally. Not that I would know anything about that.

author: floobydust
author_rank: Super Contributor
timestamp: October 02, 2021, 10:31:04 pm
content: I use a bunch ofJ-B WeldPlastic Bonder "High Strength Structural Adhesive" and it's non-conductive epoxy, could not get an ohmeter reading probes right close on a big blob.OP's Twin Tube "steel reinforced"ingredient listhas no "steel"it's fiberglass and barium sulfate hardener, a bit of titanium dioxide. They might mean it adheres to steel, it's not made of steel.

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 03, 2021, 08:56:58 am
content: In section 8, it says that only substances with limit values have been included in the list, so I guess steel doesn't have to be included as it's not considered dangerous.

author: Ian.M
author_rank: Super Contributor
timestamp: October 03, 2021, 09:09:16 am
content: iRepairElectronics said JB Weld can be picked up with a magnet (#1 above), and if anyone else cares to check, just see if a magnet is attracted to either component in its tube, as metal squeeze tubes are non-ferrous. If its ferromagnetic, as it claims to contain steel, Occam's razor would suggest that it does indeed contain steel powder.If the electrical properties of a hardware store epoxy are important to you, get clear or white epoxy (to avoid possibly conductive fillers) , and be careful to mix it in the exact proportions specified by the manufacturer to avoid incomplete polymerisation.

author: floobydust
author_rank: Super Contributor
timestamp: October 03, 2021, 08:59:36 pm
content: J-B Weld Kwik from msds:Iron 7439-89-65 - 10%Limestone 1317-65-310 - 30%Oxirane, 2,2-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bis, homopolymer 25085-99-810 - 30%Phenol, 2,4,6-tris[(dimethylamino)methyl]-90-72-21 - 5%Phenol, polymer with formaldehyde, glycidyl ether 28064-14-41 - 5%Carbon black 1333-86-40.1 - 1%Titanium oxide 13463-67-70.1 - 1%My J-B Weld Plastic Bonder is not magnetic. I had an email war with J-B Weld because they don't list what plastics don't work with it, like polypropylene. Grrr.

author: WattsThat
author_rank: Frequent Contributor
timestamp: October 03, 2021, 11:55:47 pm
content: None of the slippery, oily, paraffin like materials are going to stick well to anything due to what the eggheads call low surface energy. Polyethylene and polypropylene are the two most common materials because they’re the cheapest polymers out there. Heck, the only way you can reliably print on them is to etch them with corona discharge or a flame treatment.PP and PE can be fused together with heat and pressure but trying to glue the stuff? Not sure but a specialized cyanoacrylate might work as I know of stuff that can even stick to PTFE (Teflon).

author: BrokenYugo
author_rank: Super Contributor
timestamp: October 04, 2021, 12:25:27 am
content: There do exist special epoxies for such plastics, I recall using one once that McMaster sold, it was expensive (I think nearly $100 for a small twin tube of the stuff) and had a bizarre surface prep ritual that involved passing a cool propane flame over the plastic shortly before mixing and applying the adhesive. Worked quite well on delrin.

author: floobydust
author_rank: Super Contributor
timestamp: October 04, 2021, 01:02:52 am
content: At the time, I needed a glue for conductive carbon-filled plastic films like Velostat/Linqstat. Those are polyethylene, I can't remember what I'd bought thought it was PP.Nothing glued very well to them. Even triedLoctitetwo-part cyanoacrylate Plastics Bonding System and then gave up. The PE plastic is excellent as a masking for glue lol probably great for potting boxes.Loctite Design Guide for Bonding Plasticshas lots and it mentions dielectric strengths as well, if OP uses Henkel products.

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: October 04, 2021, 01:14:27 am
content: It's easy enough to find out:https://www.jbweld.com/faqsQ: "Will J-B Weld conduct electricity?"A: "No. J-B Weld is not considered to be a conductor. It is an insulator."

author: DAVEISGREAT
author_rank: Regular Contributor
timestamp: June 19, 2023, 06:02:06 am
content: I've potted small low voltage/low power circuit boards with JB Weld without issue. High voltage is another beast.

author: TERRA Operative
author_rank: Super Contributor
timestamp: June 19, 2023, 07:52:38 am
content: Quote from: floobydust on October 04, 2021, 01:02:52 amOh, that Design Guide for Bonding Plastics is a really useful document, thanks for the link! (I often use 401 for all the superglue jobs I have, it's good stuff)

author: Mario87
author_rank: Frequent Contributor
timestamp: June 20, 2023, 10:09:05 am
content: Likely depends on the voltage, one user her said it does not conduct when tested with a DMM which is what...3VDC to 9VDC or so (depending on the batteries used)?? It would be very different when performing a Hi-Pot Isolation test at 500V or 1kV or even higher.So it depends on your application as to whether or not it is suitable. On a car where the system is 12-14.4VDC, then yeah, most likely fine, on something that is near mains AC voltages (where it's capacitive reactance comes into play), then nope, I would not trust it unless you have the correct (expensive) equipment to test it at such voltages and prove it has high isolation at those voltages.

author: fricker
author_rank: Newbie
timestamp: October 12, 2023, 11:05:43 am
content: Regarding the 'J B Weld' epoxy you've mentioned, in its fully cured state, it is generally not conductive and is often used for electrical insulation purposes. It's designed to provide a strong bond while remaining non-conductive to prevent electrical conductivity or short circuits.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 12, 2023, 02:03:24 pm
content: It has high resistivity,http://www.aeroelectric.com/Mfgr_Data/JB_Weld/JB-Weld-Technical-Datasheet.pdfI don't see any data on breakdown or dielectric constant, probably suggesting it's not recommended for such application.I have used it before, in a pinch, to insulate connections on noncritical parts (i.e. that will be used with supervision). I wouldn't recommend it for anything permanent. There are, however, plenty of clear and ceramic-filled epoxy blends that are rated for voltage, that are hardware-store available.Tim

author: DAVEISGREAT
author_rank: Regular Contributor
timestamp: February 20, 2024, 07:34:53 pm
content: Quote from: Ian.M on October 03, 2021, 09:09:16 amThe cream colored hardener is non-magnetic while the grey epoxy steel tube is definitely magnetic. Ran out of clear epoxy, so I used steel epoxy to pot and isolate POS and NEG in a low voltage hobby application since resistance appears to be barely measurable. Still, best not to use steel epoxy in permanent applications.