For a rigid metal-to-metal bond, a two-part syringe epoxy such as J-B Weld Original is a practical general-purpose choice when you can allow its full cure. For filling an irregular gap, patching, or rebuilding a worn area, a moldable epoxy putty such as J-B Weld SteelStik is easier to shape. Neither is proven universally strongest: their manufacturers publish different figures, and those figures are not results from a common comparative test.
Which metal epoxy fits your repair?
Choose by the shape of the repair and the conditions it must withstand, not by a strength number or set time alone. A liquid two-part epoxy is suited to bonding surfaces that can be fitted together; a putty is suited to repairs where material needs to be pressed into a gap or shaped around a damaged part.
| Product | Best fit | Manufacturer-published details | What the figures do—and do not—tell you |
|---|---|---|---|
| J-B Weld Original, 25 ml syringe | General rigid repairs and bonding, including metal | 1:1 mix; 6,220 PSI tensile strength; sets in 4–6 hours; full cure in 15–24 hours at room temperature; up to 550°F when fully cured. J-B Weld product page | The strength is the maker’s published value, not a head-to-head result against the other products listed. |
| J-B Weld SteelStik, 2 oz putty | Shapeable patching, gap filling, and rebuilding metal components | 4,000 PSI strength; sets in 5 minutes; listed cure time of 1 hour; up to 350°F. J-B Weld product page | A putty and a syringe adhesive have different forms and uses; the published number is not a controlled comparison with Original. |
| Loctite Epoxy Metal & Concrete, 25 ml | Metal or concrete repairs and gap filling | Two-part, equal-volume syringe; sets in 5–12 minutes; described as water- and humidity-resistant and machinable after cure. Loctite product page | The cited product page does not provide a directly comparable strength value. |
| Loctite Epoxy Instant Mix 5 Minute, 0.47 oz | Small, quick repairs on several materials, including metal | Sets in 5 minutes; handling strength in 1 hour; described as sandable and drillable. Loctite product page | It is a general-purpose epoxy; check its label or data sheet for fit with the joint and service conditions. |
J-B Weld says its Original product selection guidance covers “Metals: all, including aluminum and cast iron.” That is the manufacturer’s compatibility guidance, not a guarantee that every metal joint or repair will succeed. For dissimilar metals, a loaded joint, or a repair exposed to demanding service, confirm suitability with the exact product label or technical data.
How to choose: joint shape, cure, and service conditions
For a close-fitting, rigid joint
Consider a two-part syringe epoxy when the metal parts can be aligned and held in position while the adhesive cures. J-B Weld Original is mixed 1:1 and has a much longer set and cure schedule than a quick-setting option: its manufacturer lists a 4–6-hour set and a 15–24-hour full cure at room temperature. Plan to keep the repair undisturbed for the time specified on the current package.
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- J-B Weld is The Original Cold-Weld two-part epoxy system that provides strong, lasting repairs to metal and multiple surfaces. Mixed at a ratio of 1:1, it forms a permanent bond and can be shaped, tapped, filed, sanded and drilled after curing. At room temperature, J-B Weld sets in 4-6 hours to a dark grey color. Full cure is reached in 15 hours. J-B Weld has a tensile strength of 6220PSI and sets to a hard bond overnight. It can withstand temperatures up to 550°F when fully cured
- CURE AND SET TIME: J-B Weld Original High-Strength Syringe sets in 4-6 hours and cures in 15 hours.
- STRENGTH: J-B Weld Original Syringe has tensile strength oF 6220PSI.
- GREAT FOR: Great for household repairs, automotive, plumbing, marine, crafts and more.
- DO IT YOURSELF: Big or small, you can DIY it with J-B Weld. Our heavy duty epoxy and adhesives repair & restore it right the first time. J-B Weld delivers superior performance, quality, and results for the World’s Strongest Bond.
For a gap, patch, or missing material
A moldable putty can be pressed into an irregular area and shaped to rebuild a component. J-B Weld describes SteelStik for patching and rebuilding metal parts. Its listed 5-minute set and 1-hour cure are manufacturer specifications; they are not evidence that it will produce a stronger or weaker bond than a liquid epoxy in a different joint.
For a faster set or a machinable repair
Loctite’s Metal & Concrete epoxy is described as setting in 5–12 minutes and as machinable after cure. Its Instant Mix 5 Minute product is described as setting in 5 minutes, reaching handling strength in 1 hour, and being sandable and drillable. “Set,” “handling strength,” and “full cure” are different milestones; follow the selected product’s instructions before loading, machining, or exposing the repair.
Rank #2
- Ready-to-use liquid weld for rigid parts: Metal epoxy glue bonds aluminum, steel, stainless, and cast iron; also wood, ceramic, glass, rigid plastics, and concrete—ideal for auto repair, marine hardware, plumbing leak repair, and home fixes.
- 30‑minute working time, 24‑hour cure: True 1:1 mix lets you align, clamp, and build thickness. Cures to a dense, steel‑like mass up to 4680 PSI; repair is drillable, sandable, fileable, and paintable for clean finishes.
- Built for real conditions: After full cure it’s waterproof, oil‑ and chemical‑resistant, and handles ‑85°F to 356°F—reliable in engine bays, outdoor equipment, shop use, boats, and garages.
- Clean, controlled application: Pre‑filled dual syringe meters the ratio accurately; paste‑like, no‑drip formula stays put on vertical or overhead surfaces—great for brackets, housings, radiators (non‑pressurized), tools, patio furniture, and fences.
- Strong repair tips + limits: Scuff/degrease, mix 1:1, spread 0.5–1 in beyond damage, clamp, and reinforce stress points with mesh/patch/bracket; allow 24 hrs before load or machining. Not for PE, PP, PTFE, silicone, rubber‑like or flexible parts, moving joints, or pressure‑critical lines.
For heat or moisture exposure
J-B Weld lists maximum temperatures of up to 550°F for Original when fully cured and up to 350°F for SteelStik. These are product-specific manufacturer claims, not interchangeable ratings. Loctite describes Metal & Concrete as water- and humidity-resistant, but that description alone does not establish suitability for every immersion, pressure, or outdoor condition. Check the exact product label and data sheet against the repair’s actual exposure.
Will epoxy bond metal to metal?
Yes, epoxy products are made for metal repairs, but a successful bond depends on more than the word “metal” on the package. The fit and area of the joint, surface condition, mixing, cure, and forces on the repair all matter. J-B Weld’s FAQ recommends roughening surfaces to help ensure a sufficient bond and names aluminum and cast iron among metals covered by its Original product guidance. Follow the instructions for the particular product you choose, especially if the repair joins dissimilar metals or will carry a significant load.
Rank #3
- J-B Weld Kwikweld: A Fast Setting Version Of The Original Cold Weld Two-Part Epoxy System That Provides Strong, Lasting Repairs To Multiple Surfaces. Perfect For Diy Household, Automotive, Marine, Craft Repair And Much More
- Cure And Set Time: After Mixing The Tubes At A 1: 1 Ratio, It Takes 6 Minutes To Set And 4-6 Hours To Cure. Once Cured, Kwikweld Can Be Tapped, Filled, Sanded, Molded And Drilled. Kwikweld’S Set And Cure Color Is Dark Grey
- Versatile And Dependable: J-B Weld Kwikweld Is Steel Reinforced, Has A Tensile Strength Of 3127 Psi And Can Withstand Temperatures Up To 230 Degrees Fahrenheit (110 Degrees Celsius). When Fully Cured, Kwikweld Is Waterproof And Resistant To Petroleum, Chemical And Acid
- Surface Applications: Metal, Plastic & Pvc, Wood, Concrete, Ceramic & Tile, Fiberglass And More
Prepare metal and apply epoxy correctly
- Check the product instructions. Confirm metal compatibility, mixing ratio, application temperature, working time, personal protection, and full cure instructions on the product label and safety data sheet. J-B Weld specifies a 1:1 mix for Original; do not assume another product uses the same ratio.
- Roughen the bonding area. J-B Weld recommends light sandpaper or abrasive cloth before application. Roughen the area to be bonded without changing the fit of the parts.
- Clean the surface. J-B Weld recommends cleaning with acetone or lacquer thinner; if those are unavailable, its FAQ says soap and water may be used. Use solvents only as directed and with appropriate precautions.
- Let the metal dry completely. Do not apply epoxy over moisture or cleaning residue.
- Mix and apply as directed. Observe the product’s specified ratio and working time, then bring the parts together or shape the putty as appropriate. Hold or support the repair as the instructions require.
- Wait for the stated cure before use. Do not treat an initial set or handling-strength milestone as permission to load the repair if the manufacturer specifies a longer full cure.
Why published strength numbers cannot identify a universal winner
The listed PSI values come from separate manufacturer pages. The evidence available for these products does not establish a shared test method, substrate preparation, joint geometry, or curing conditions across brands and forms. Tensile strength figures should therefore not be ranked as if the products were tested side by side. A product’s listed number also cannot, by itself, predict how a particular repair will perform.
Choose the product whose form, cure schedule, temperature rating, and stated use match the job, then follow its current package and data sheet. If failure could cause injury or significant damage, do not rely on a general-purpose epoxy as a substitute for a repair method rated for that application.
Quick Recap
Best Value
- Dries clear: Our Gorilla Tough epoxy resin dries clear for a clean finish and incredibly durable hold; perfect for household and automotive repairs
- 5 minute epoxy: This epoxy resin kit in just one applicator has a 5 minute set time, plenty for repositioning and adjusting
- Gap filling: Gorilla resin epoxy also acts as a gap filler, filling voids and bonding uneven or vertical surfaces
- Water resistant: Our clear epoxy resin withstands moderate exposure to water for extra durability
- Easy-to-use syringe: Gorilla Epoxy has separate barrels of epoxy resin and hardener to keep the epoxy from hardening; the syringes dispense evenly and include a cap for multiple uses
Rank #4
- J-B Weld Steelstik: A Hand Mixable Two Part Epoxy Putty Stick That Is Steel Reinforced & Non-Rusting To Quickly Repair Or Rebuild Anything Made Of Metal! J-B Weld Steelstik Is Certified By The Nsf And Is Safe For Contact With Potable Water
- Cure And Set Time: After Kneading The Two Part Formula Together By Hand, Steelstik Takes 5 Minutes To Set And Cures In 1 Hour. J-B Weld Steelstik Set And Cure Color Is Dark Grey
- Product Features And Strength: J-B Weld Steelstik Has Lap Shear Strength Of 900 Psi, Can Withstand Continuous Temperatures Up To 350F (176C ) And Intermittent Temperatures Of 450F (232C), And Is Chemical Resistant Against Petroleum, Hydraulic Fluids And Other Chemicals When Fully Cured. Steelstik Can Be Molded, Shaped, Sanded, Drilled And Tapped
- Surface Applications: Iron & Stainless Steel, Copper & Brass, Aluminum & Bronze, Fiberglass And Plastic & Pvc
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