Like all other epoxies, these are two-part adhesives which must be mixed to cure. Curing is a chemical reaction rather than the drying most adhesives depend upon. This means that these adhesives will cure in any environment, even when they're submerged in water.

Most epoxies add strength to a joint when the epoxy-joint layer is minimized. Epoxy, in and of itself, doesn’t carry strength. Its the cross-linking nature of the epoxy establishing bonds between the materials forming the joint. Long spans (think gaps) between the articles forming the joint creates a weak bond- the epoxy is making longer bonds to the materials to be joined. A thin gap is best. JB Weld has small metallic materials in suspension, so some gap filling will work with this original formulation. I made it 230 miles to Harmony, Pennsylvania, by nightfall, and I pounded out the remaining 620 miles to Boston the following day without incident.

So, what do these results tell us? Cheap five-minute epoxy isn’t terrible, and actually better than the fancy new versions of JB Weld. Loctite is okay, and the Devcon and original JB Weld are at the top of their game. That’s not that surprising, as you can cast cylinder heads for engines out of JB Weld.

But an oil leak onto the exhaust threatened to derail the trip. The leak was due to the valve cover stud in the lower left corner of the head being stripped in its hole and thus not tightening, which prevented that corner of the valve cover from sealing. This caused oil to drip directly onto the downpipe, which was a clear fire hazard. At the time, I repaired the stripped threads with a Time-Sert (helicoil). The car still appeared to be weeping a small amount of oil through the threads onto one of the exhaust studs, but this is a common problem, as the lower exhaust studs thread directly into oil runoff area on the low side of the head. I made it home without incident, and that spring I road-tripped the car 2000 more miles to other events. Generally speaking, these waterproof epoxies are referred to as "marine epoxies" because they are primarily used for the manufacture and maintenance of boats. All marine epoxies are water stabilized, ensuring that their bond isn't compromised by continual submersion in water. There are special purpose epoxy adhesives for all sorts of applications. But for most projects and repairs, a general purpose epoxy works just fine. Unless there's some reason to use a special purpose epoxy, you might as well use the all-purpose ones and save yourself the extra cost of those specialty adhesives. Test sample: Original Cold-Weld Formula applied to both bond surfaces of low-carbon steel sample pieces and squeezed together with hand pressure. Since 2008, the company has broadened the product line to add J-B SteelStik, KwikWood, PlasticWeld, MarineWeld, Perm-O-Seal, WoodWeld and ClearWeld. [5] [6] J-B Weld epoxy [ edit ]

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Also, adding reinforcement can increase the strength of the joint. Bonding additional pieces of wood or metal over an epoxied joint can mechanically stiffen the joint and help it to better withstand the variety of forces that act on it. J-B Weld can be used to bond surfaces made from metal, porcelain, ceramic, glass, marble, PVC, ABS, concrete, fiberglass, wood, fabric, or paper. [7] [8] Alcohol should be avoided when cleaning surfaces, as it can degrade the bond. [9] Surface prep is key. Clean is good, but rough is better. The epoxy needs to grab onto the surface. If there are edges, the epoxy can grab on to, the adhesion will be better. You’ll get your best results with J-B Weld by applying it to a clean, roughened surface. Roughness (within reason) counts for a lot. First, it increases the bond surface area. When seen under magnification, a roughened surface has more area compared to a smooth one. You can picture this pretty easily if you consider, say, the surface of the moon versus the surface of a marble the size of the moon. Although both have theoretically the same surface area, the irregularities on the moon’s surface would provide increased surface to which to apply adhesive.