What is NuMetal Epoxy Putty?
NuMetal Epoxy Putty is a two-part hand-mixable epoxy putty that bonds, fills, seals and rebuilds damaged metal, plastic, wood, fiberglass, concrete and ceramic, curing to a machinable solid with 12,000 psi compressive strength. NuMetal mixes at a 1:1 ratio with no weighing or measuring, adheres to damp surfaces, and cures fully underwater in about 12 hours.
12,000 psi
Compressive Strength
300°F
Max Use Temperature
1:1
Mix Ratio, No Measuring
NuMetal Epoxy Putty mixes like clay but hardens like steel. NuMetal bonds, seals, fills, insulates, anchors, caulks and waterproofs in a single step, and once cured it can be drilled, tapped, sanded, primed and painted like solid stock.
NuMetal cures without shrinking or sagging, so NuMetal holds its shape on vertical surfaces and overhead repairs where a pourable epoxy would run off the job. NuMetal also sticks to damp surfaces and will cure completely underwater, which makes NuMetal the practical choice for a leaking pipe, a pool wall, or a boat hull that cannot be drained first.
Color matters more than it looks. Black NuMetal is the automotive choice, because if the surface coating over the repair later chips or scratches, the black putty underneath stays invisible. White NuMetal suits marine work and gelcoat repairs on boats. Tan and Grey cover wood, stone, concrete and general shop repairs.
NuMetal bonds to almost anything, cures underwater, and shrinks zero percent. Satisfaction guaranteed!
NuMetal Steering Wheel Repair — Part 1
NuMetal Epoxy Putty bonds to steel, cast iron, aluminum, copper, brass, fiberglass, wood, concrete, brick, stone, tile, ceramic, glass, pottery, PVC and ABS. NuMetal reaches 375 psi bond strength on properly prepped surfaces, and roughing the substrate with sandpaper before application improves adhesion on every one of these materials.
- Steel and Cast Iron — Rebuild cracked engine blocks, radiators, battery cases and machine housings. Once cured, NuMetal can be drilled and tapped like the parent metal.
- Aluminum, Copper and Brass — Seal pinholes in coolant and fuel lines, water fittings and refrigeration coils without heat or torch work.
- Fiberglass and Gelcoat — Fill scrapes, dents, chips and holes on boat hulls, decks and RV panels. White NuMetal blends best under gelcoat.
- PVC and ABS Plastic — Repair pool plumbing, sprinkler lines, waste lines and underground pipe fittings, including fittings that stay wet.
- Concrete, Gunite and Masonry — Patch cracks in pool walls, plastered walls, steps, decks and brickwork.
- Wood — Rebuild rotted or gouged furniture, trim and boat woodwork. NuMetal takes stain and paint after curing.
- Tile, Ceramic, Stone, Glass and Pottery — Bond broken pieces and fill missing chips on tubs, sinks, toilets and household items.
- Rubber Gaskets and Seals — Form emergency gaskets and seal broken control handles, knobs and hardware.
- Damp and Submerged Surfaces — NuMetal applies to wet surfaces and cures underwater, which no solvent-based filler will do.
Does NuMetal Really Cure Underwater?
NuMetal cures underwater and on damp surfaces because NuMetal's epoxy reaction is not dependent on air drying or solvent evaporation. Clean loose material, algae or slime off the surface first, then press the mixed putty firmly into place. Pool wall cracks, submerged pipe fittings and below-waterline hull repairs are all standard NuMetal jobs.
Can NuMetal Be Used as an Adhesive?
NuMetal works as a structural adhesive as well as a filler and bonds dissimilar materials to each other, such as metal to wood or ceramic to plastic. Rough up or lightly sand both faces before joining them, then clamp or hold the parts until NuMetal begins to set at about one hour.
- Cures Underwater: NuMetal sticks to damp surfaces and cures fully submerged, so pool, pond, tank and bilge repairs do not require draining the system first.
- Zero Shrinkage: Tested at no measurable shrinkage (D2566) at 75°F. The repair you shape is the repair you get, with no sink marks to fill later.
- Will Not Sag on Vertical Surfaces: NuMetal holds its shape on walls, overhead panels and the underside of a floorpan without slumping.
- Machinable After Cure: NuMetal can be sanded, drilled, routed, screwed, chiseled, tapped, sawed, turned, filed and carved once fully cured at about 12 hours.
- Takes Paint, Stain and Gel Coat: Finish NuMetal with primer and topcoat, wood stain, or marine gelcoat. Black NuMetal hides under automotive coatings if the topcoat later chips.
- 300°F Heat Resistance: NuMetal holds up to a 300°F (149°C) maximum use temperature, which covers engine bay, exhaust-adjacent and HVAC repairs.
- Easy 1:1 Mix, No Measuring: Cut equal lengths of the A and B bars with a ruler as a guide. No scale, no pumps, no pot-life panic across a whole batch.
- Cut Only What You Need: Use a walnut-sized piece for a small repair and reseal the rest in the supplied zip bag. Nothing is wasted on a small job.
- Soap and Water Cleanup: Clean tools, gloves and hands with warm soapy water immediately after use. No acetone or lacquer thinner required.
NuMetal Epoxy Putty repairs pool and spa plumbing, marine hulls and fuel lines, RV and automotive fittings, household plumbing and fixtures, and industrial drums and lines. Any job that needs a gap filled, a crack sealed or a broken part rebuilt on metal, plastic, wood, fiberglass, concrete or ceramic is a NuMetal job, including repairs made on wet or submerged surfaces.
- Pool & Spa
- Tile and grout, PVC and ABS pipe, underground pipe fittings, cracked pump housings, skimmers, pool and concrete decks, cracked timer and control boxes, filter grids and screens, broken control handles and knobs, cracks in pool gunite, plastered walls, bottoms and steps, broken pool tools, cracked coping, mounting hardware, ladders, hand rails, diving boards, water fittings and gaskets.
- Marine, Yacht and Boat
- Scrapes, dents, chips, holes, leaks and breaks in fiberglass, wood, metal and plastics. Broken fuel lines, cracked water lines and tanks, waste system repairs for tanks and lines, bonding loose carpet, and emergency repairs to engine fuel and water lines.
- RV & Auto
- PVC and ABS pipe, water lines, fittings and tanks, broken fixtures, chipped grills, handles, emergency repairs to engine fuel and coolant lines, gaskets, plumbing cracks and leaks, furniture, wood, fiberglass, ceramic and plastic, tubs, toilets, sinks, tiles and caulking, emergency repairs for radiators and cracked engine blocks, and battery terminals and cases.
- Home & Household
- Furniture, water lines, PVC and ABS pipe, dents, scrapes, chips and nicks in cast iron, brick, concrete, tile, ceramics, stone, glass, pottery, wood and plastic. Sprinkler line repair, sealing underground connections and elbows, cracks and leaks in plumbing fixtures, tubs, toilets, sinks, tiles and caulking, broken filling on appliances, air conditioning and refrigeration coils, and attaching golf club shafts to golf club heads.
- Industrial
- Leaking drum repair, water and air lines, HVAC coolant and refrigeration lines, and plumbing fixtures.
- Restoration & Bodywork
- Rebuilding cracked steering wheels, filling pitted or holed sheet metal in combination with BackBone Reinforcing Mesh, and forming a machinable base that accepts primer and topcoat. Black NuMetal is the automotive choice because it stays invisible if the finish over it is later damaged.
NuMetal gives roughly 30 minutes of working time after mixing, begins to set about 1 hour from the end of mixing, and reaches a steel-hard full cure in about 12 hours at 75°F. Mixing time itself runs at least 2 minutes for a walnut-sized piece and at least 15 minutes for a full pound.
| Stage | Time at 75°F |
|---|
| Kneading (walnut-sized piece) | 2 minutes minimum, until one uniform color |
| Kneading (full 1 lb) | 15 minutes minimum |
| Working time after mixing | Approximately 30+ minutes |
| Begins to set | About 1 hour (D2471: ~60 mins) |
| Full steel-hard cure | About 12 hours |
| Shelf life, unopened | At least 2 years from date of purchase |
| Shelf life, opened and resealed | Typically 6 months when stored per the directions |
Temperature changes everything: NuMetal below 70°F is stiffer, harder to knead and slower to set. NuMetal above 90°F is softer and easier to mix but has a noticeably shorter work life and sets much faster. Mix at 75°F or above for predictable results, and blow warm air on a cold repair to speed hardening.
Pro Tip: Wet your fingertips with water and feather the surface BEFORE NuMetal starts to set. A wet-finger finish is smooth enough that most repairs need no sanding at all. Wear gloves, and take off rings before you start.
What Are NuMetal's Physical Properties?
| Bond Strength (D1002) | 375 psi |
| Tensile Strength (D412) | 4,000 psi |
| Compressive Strength (D695) | 12,000 psi |
| Coefficient of Thermal Expansion (TMA) | 4x105 |
| Dielectric Strength (D149) | 300 volts/mil |
| Maximum Use Temperature | 300°F (149°C) |
| Hardening Time at 75°F (D2471) | Approximately 60 minutes |
| Shrinkage at 75°F (D2566) | None |
NuMetal differs from liquid two-part epoxy in that NuMetal is a moldable solid rather than a pourable liquid: NuMetal is cut 1:1 by hand with no scale, holds its shape on vertical and overhead surfaces, and cures underwater, while liquid epoxy must be measured by ratio and will run off anything that is not flat and dry.
| | NuMetal Epoxy Putty | Liquid Two-Part Epoxy |
|---|
| Mixing method | Cut equal lengths, knead by hand, no scale needed | Measured or pumped by ratio, mixing errors change cure |
| Vertical and overhead use | Yes, will not sag or run | Typically no, runs off unless thickened |
| Wet or submerged surfaces | Yes, applies damp and cures underwater | Generally no, most require a dry substrate |
| Gap filling and rebuilding | Yes, moldable to any shape and thickness | Limited, fills only what it can be dammed into |
| Shrinkage on cure | None measured (D2566) | Varies by formula, many shrink slightly |
| Partial use of the package | Yes, cut only what is needed and reseal the rest | No, mixed portion cures whether used or not |
Liquid epoxy is the better choice when the job needs deep penetration into a porous substrate, a thin flowing laminating layer over fiberglass cloth, or a clear pourable finish, since NuMetal is an opaque solid that stays where it is pressed.
NuMetal cures to a paintable, machinable surface. Finish the repair so the substrate around it is protected too.
- Step 1 — Clean With KBS Klean
- Remove grease, oil, gasoline and dirt from the area before mixing NuMetal. KBS Klean is the recommended prep and is water-based, so it will not leave a solvent film that blocks adhesion.
- Step 2 — Shape, Cure and Sand
- Press NuMetal into the repair, feather it with wet fingertips, and let it cure about 12 hours. Sand, drill, tap or file the cured putty to final shape.
- Step 3 — Coat With RustSeal
- On metal repairs, coat the finished area with RustSeal to stop rust from restarting around the patch. RustSeal bonds over cured NuMetal and over the surrounding rusted or prepped metal.
- Step 4 — Topcoat
- Add DiamondFinish Clear or a color topcoat for UV protection and appearance. Wood repairs take stain directly; marine repairs take gelcoat.
Shop RustSeal
NuMetal Directions & Technical Data Sheet
Full prep, mixing, shaping, cleanup and storage steps, plus the complete physical property table.
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BackBone Reinforcing Mesh
How to back up a hole with fiberglass mesh so NuMetal bridges the gap instead of falling through it.
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RustSeal Rust Encapsulating Coating
The coating to put over a cured NuMetal repair on metal so rust does not restart around the patch.
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KBS Klean Surface Cleaner
The recommended prep step before NuMetal. Water-based cleaner that strips grease, oil and grime.
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KBS Application Guides
Step-by-step guides and product directions across the full KBS Coatings line.
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Customer Restoration Photos
Real projects from KBS customers showing repairs and coatings before and after.
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Part 1: Cleaning and prepping a cracked steering wheel, then mixing and packing NuMetal into the crack.
Part 2: Shaping, curing, sanding and finishing the repaired steering wheel.
