How to glue metal to metal: epoxy putty and clear epoxy glue

To glue metal to metal, use a two-component epoxy. Metal epoxy putty bonds and rebuilds parts made of steel, including stainless steel, aluminium and brass, seals holes and leaks and withstands −60 °C to +150 °C; after 2.5 hours the repair can be drilled, sanded and loaded. For a thin, colourless seam, for example metal to glass or plastic, use a clear epoxy glue.

What you need

Metal epoxy putty, 55 g

Two-component cold weld, 55 g

Super glue colorless, 10 g

Colorless, 10 g

Which product to choose

• Metal epoxy putty — a plasticine-like epoxy compound with iron powder. It bonds parts, rebuilds missing fragments, forms threads and seals leaks in pipes, taps and radiators. Cast iron and copper are bonded once cleaned back to bare metal.
• Clear epoxy glue — for a thin, colourless, elastic seam: metal to metal, plastic, wood, glass, rubber and leather. The seam withstands water, frost and vibration.

Epoxy compounds are not suitable for the silencer and exhaust system, which get hotter than +150 °C in use, or for surfaces in contact with food and drinking water pipes.

How to glue metal to metal — step by step

1. Prepare the surfaces. Clean dirt and rust off the metal, rough it up with coarse sandpaper, degrease and dry it. Clean cast iron and copper back to bare metal.
2. Knead the epoxy putty. Cut at least 1/3 off the stick of NANOPROTECH Metal epoxy putty across its whole cross-section and knead it with your fingers, wet if you like, until the colour is uniform.
3. Or mix the clear glue. Squeeze equal amounts from both bottles of Super glue colorless onto a dry, clean plastic or wooden surface and mix until uniform. The mix stays workable for 1–1.5 hours at +20 °C.
4. Apply and press the parts together. Apply the compound to both surfaces and press them together. Hold parts joined with the putty for 15 minutes, and parts joined with the glue for 2–3 hours.
5. Fill a hole or chip. Fill the damage with the putty and shape it with a flat object moistened with water. The putty sets in 45 minutes.
6. Wait for full strength. After 2.5 hours a putty repair can be drilled, sanded, painted and loaded. A joint made with the clear glue can take load after 24 hours.

A leaking pipe is repaired with the water turned off and the pressure released: see how to fix a leaking pipe with epoxy putty. In pressurised systems this is a temporary repair until the section is replaced.

Why it may not work

• The putty came away from the metal. The surface was not sanded or degreased. On an oily surface the bond strength is 20% lower, so degrease the repair area.
• The joint did not withstand the heat. The cured compound withstands up to +150 °C; the silencer and exhaust system get hotter.
• The putty did not reach full strength. Less than 1/3 of the stick was cut off, or it was not kneaded evenly, so the ratio of components was off.
• The stick hardened in the pack. Warm it to +60 °C for about 10 minutes, in hot water or on a radiator, and it becomes pliable again.

Safety precautions

• Wear protective gloves and keep the compounds out of your eyes. If they get in, rinse with water and seek medical advice. Wash your hands with warm soapy water after work.
• Do not use the compounds on surfaces that come into contact with food or drinking water.
• Keep the products out of the reach of children.

Frequently asked questions