PC-7 is waterproof and can do tasks like sealing cracks in a wall, sealing leaks in PVC pipe connections, granite monuments, leaks in oil pans, creating multimedia sculptures, and much more.
J-B Weld has better strength and can be used for repairs on household, marine, and automotive items, as well as DIY, accessories, and crafts.
J-B Weld KwikWeld is a faster version of the original and is also more rapid than PC-7.
For other strong bonding options, explore JB Weld vs. Araldite to compare adhesives that perform well in household and professional projects alike.
Article Highlights
- PC-7 is a heavy-duty epoxy that delivers permanent repair.
- J-B Weld is a superior performance adhesive with a stronger bond, providing lasting bonds on various surfaces.
- PC-7 seals cracks, leakages, repairs, create, and more.
- J-B Weld can do household, automotive, marine, crafts, DIY, and many more projects.
PC-7 Epoxy vs. J-B Weld
PC-7 is a heavy-duty, permanent repair paste epoxy. It comes in two-part packaging that must be mixed before use.
J-B Weld Original is a two-part, cold-weld epoxy system that can be used on multiple surfaces and provides a strong, long-lasting bond.
Strength
PC-7 has a tensile strength of 2150 PSI and provides exceptional adhesion for permanent repairs.
J-B Weld Original Cold-Weld has a tensile strength of 5020 PSI, and J-B KwikWeld has 3127 PSI, which is better and stronger than PC-7 epoxy.
If you need more specific alternatives, see how Devcon compares to J-B Weld for situations requiring strong adhesion under stress.
Setting And Curing Time
PC-7 epoxy sets in 60 minutes and cures within 24-48 hours. It can be sawed, sanded, drilled, tapped, filed, machined, filed, and painted.
After priming, the surface can be painted with iron oxide or carbon pigments.
Also, ensure that there is not too much tint, as it can affect the epoxy’s performance.
On the other hand, the J-B Weld Original takes 4-6 hours to set and 15-24 hours to cure.
KwikWeld is a lot faster, as it takes 6 minutes to cure and 4-6 hours to sand. They can also be tapped, filled, drilled, and molded.
Color
PC-7 turns dark gray once cured. It is waterproof, sandable, and paintable, which makes it versatile for many projects.
It comes in two parts: one is black, and the other is gray, which makes it dark gray after mixing.
J-B Weld Original and KwikWeld turn dark gray after being properly cured. They come in two-part tubes: one is white, and the other is gray.
Consistency
PC-7 epoxy has a thick paste consistency, which is suitable for heavy-duty use and forming permanent bonds.
Also, paste-like epoxies have extra working time for more extensive projects suitable for critical tasks.
J-B Weld Original and KwikWeld come in a liquid formulation. It is easy to apply and can precisely get into complex spaces.
Compatible Materials
PC-7 epoxy works with multiple surfaces, including wood, metals, glass, fiberglass, plastics, rubber, masonry, ceramic, tile, and all combinations.
However, it doesn’t bond to wax paper, vinyl, Teflon, plexiglass, and some softer plastics.
J-B Weld Original also works on multiple materials, such as wood, ceramic, fiberglass, stone, metal, concrete, plastic, and rigid plastics.
Applications
PC-7 epoxy is a good product for DIY and professional projects.
It can seal cracks in a wall, fix a leak in an oil pan, fix a leak in a PVC pipe connection, create a granite monument, attach a hanger to a ceramic plaque, create a multimedia sculpture, and have many more applications.
J-B Weld Original can do DIY, automotive, home repairs, marine, plumbing, and crafts.
It can also effectively repair outdoor equipment, agricultural equipment, personal watercraft, boats, in/outboard engines, deck and hull accessories, motorcycles, toys, and many more projects.
Method of using
PC-7 epoxy comes in a two-part package. One is in part A in gray color and part B in black.
Mix both parts (epoxy resin and polyamide hardener) in a 1:1 ratio.
Simply mix until you can no longer see the different colors of the parts. Unlike other epoxies, PC-7 doesn’t require an exact 1:1 ratio.
I can work with plus or minus 25% of parts A and B, and the performance will be the same.
J-B Weld also comes in two-part packaging. One is gray, and the other is white.
It should be mixed at a 1:1 ratio. Apply it to the needed areas, then let it sit for the required time to cure.
Temperature
The PC-7 epoxy can withstand -30°C to 95°C. On the other hand, J-B Weld Original can withstand 550°F/287°C.
Resistance And Special Features
PC-7 has exceptional adhesion for permanent repairs.
It is waterproof and nonconductive and has chemical resistance to caustics, mild acids, gasoline, fuel, oil, fresh water, salt, and detergents.
It also doesn’t drip or sag and delivers a bond of tremendous strength.
J-B Weld Original is waterproof, non-toxic, and resistant to chemicals, fuel, acid, and petroleum once fully cured.
Caution
PC-7 epoxy is an irritant to the skin and eyes, and it can cause allergic skin reactions.
Therefore, it must be kept away from the eyes and skin. For precautions, wear approved NIOSH masks when sanding.
If it gets into the eyes, flush it for 15 minutes, and then get medical help. Also, wash it with soap and water.
Editor’s Note
PC-7 epoxy is good-quality for building long-lasting, permanent, and tremendous strength.
The formulation of PC-7 is slow-curing, so it’s good for tough, large projects that should be done carefully.
It’s also thick in consistency. This makes it good if you want to apply it to vertical surfaces or hold something to adhere.
J-B Weld Original is a superior-strength adhesive. It has better tensile strength, and KwikWeld is faster curing than PC-7.
So, for tough jobs, you can try PC-7. And for better strength, durability, and quality, J-B Weld Original is the best.