Harry P. Posted June 8, 2015 Share Posted June 8, 2015 Is JB Weld a form of epoxy? I'm talking about the old-fashioned "original" stuff that's silvery gray in color. Is it stronger than "regular" 5-minute epoxy? I mean stronger as in harder when cured, not necessarily better stick. Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted June 8, 2015 Share Posted June 8, 2015 (edited) Is JB Weld a form of epoxy? YES. I'm talking about the old-fashioned "original" stuff that's silvery gray in color. Is it stronger than "regular" 5-minute epoxy? I mean stronger as in harder when cured, not necessarily better stick. YES. I've glued water fittings into a radiator by the side of the road for an emergency fix with JB Weld, then drove the car for hundreds of miles. 5-minute epoxy never would have managed even a few minutes. Far as being "harder" goes, if the JB is well-adhered to the base material, it can actually be drilled and tapped if you're careful. Fresh material from unopened tubes makes a difference in strength, and careful control of the 1:1 mixing ratio is also important to get the stuff to perform at its best. Edited June 8, 2015 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
Harry P. Posted June 8, 2015 Author Share Posted June 8, 2015 So "regular" epoxy consists of resin and hardener, while JB Weld consists of resin, hardener, and powdered steel, I believe? That would explain how cured JB Weld is substantially harder than "regular" epoxy when cured, and can actually be drilled and tapped. The suspended steel particles give it the hardness that regular epoxy doesn't have. JB Weld is not significantly "stickier" than regular epoxy as an adhesive, but harder when cured. Correct? Quote Link to comment Share on other sites More sharing options...
DrGlueblob Posted June 8, 2015 Share Posted June 8, 2015 A farmer on the package states; " It's better than baling wire" -That's a strong stand in these parts! Quote Link to comment Share on other sites More sharing options...
southpier Posted June 8, 2015 Share Posted June 8, 2015 the JB Kwik is not as strong as the 24 hour slow cure JB (generally true of 2-part products) Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted June 8, 2015 Share Posted June 8, 2015 (edited) So "regular" epoxy consists of resin and hardener, while JB Weld consists of resin, hardener, and powdered steel, I believe? That would explain how cured JB Weld is substantially harder than "regular" epoxy when cured, and can actually be drilled and tapped. The suspended steel particles give it the hardness that regular epoxy doesn't have. JB Weld is not significantly "stickier" than regular epoxy as an adhesive, but harder when cured. Correct? The slower cure material is also "stickier" than "regular" epoxy too, and yes, in general, the fillers or modifiers added to an epoxy formulation for various applications change it's behavior...BUT the resin itself is also a major contributing factor in the performance of the stuff. Adding powdered steel to 5-minute goo will give you nothing but a low-strength gray glue. Powdered metal is added to enhance surface hardness and 'toughness' to resin-systems that are already very tough on their own. Press-dies capable of stamping 1/8" thick steel wheel centers have been made from an epoxy-powdered-steel mix. If you've ever tried to bend a 3" long piece of 1/8 inch thick steel in your hands, you'll get an idea of just how tough those dies had to be. One very high-performance epoxy-resin system I use on aircraft (MGS 285) performs as a very-high-strength structural adhesive with the addition of milled cotton fibers (cotton flock, or "flox") in European composite sailplanes. The exact same resin becomes a medium-strength structural panel adhesive when mixed with micro-balloons and fumed-silica powder, and is used to hold the US-built Cirrus SR-22 together. The same resin again becomes a non-structural lightweight filler when mixed with straight micro-balloons (but the cured MGS epoxy itself is quite hard and not easily sanded; a lower-strength, less-hard epoxy is preferred when using an epoxy-micro-balloon filler). Generally, higher-strength epoxies take longer to cure than the low-strength products, adhere to the surface they're used on much more tenaciously, and are much harder when cured. The straight MGS 285, fully cured, is considerably harder than polystyrene and can be drilled and tapped without the addition of any fillers or modifiers whatsoever. Hobby shops tend to stock several 'timed' epoxies for RC aircraft: 5 minute, 15 minute, and 30 minute. The 30 minute is the strongest and sticks best. There are hundreds, maybe thousands of epoxies for differing applications, but the generalization 'longer cure, stronger cure' holds true for all of them. Edited June 8, 2015 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
Snake45 Posted June 8, 2015 Share Posted June 8, 2015 The slower cure material is also "stickier" than "regular" epoxy too, and yes, in general, the fillers or modifiers added to an epoxy formulation for various applications change it's behavior...BUT the resin itself is also a major contributing factor in the performance of the stuff. Adding powdered steel to 5-minute goo will give you nothing but a low-strength gray glue. Powdered metal is added to enhance surface hardness and 'toughness' to resin-systems that are already very tough on their own. I don't think the standard, "regular" J-B weld has any metal in it (I could be wrong), but it's conveniently colored "white" and black so it makes it easy to tell when you've got it completely mixed, which you can't always tell with epoxies where both halves are clear. I've seen "titanium filled" J-B Weld, and wondered why. It's just titanium dust or powder, and wouldn't add any strength--only advantage I could think of was possibly increased resistance to surface abrasion, which is pretty much what you said. Thanks for the confirmation. Quote Link to comment Share on other sites More sharing options...
cobraman Posted June 8, 2015 Share Posted June 8, 2015 After talking with Bill I had JB Weld used to repair a damaged head on my 2004 Mustang GT. Lasted at least as long as we kept the car after that repair. Good Stuff. Quote Link to comment Share on other sites More sharing options...
Harry P. Posted June 8, 2015 Author Share Posted June 8, 2015 Bill, thanks for your insight. Quote Link to comment Share on other sites More sharing options...
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