How To Glue Aluminium to Aluminium

What is the best adhesive to glue aluminium to aluminium?

There are two suitable options, and they suit quite different jobs.

• A two-part epoxy such as Araldite Super Strong. You mix the two parts together to use it, and you get a rigid, very high strength bond.
• Liquid Nails Mirror & Metal, a neutral cure silicone adhesive that is ready to use straight from the cartridge.

The choice comes down to whether you need a rigid joint or a flexible one, and how large the parts are.

Rigid or flexible: how to decide

Property	Araldite Super Strong	Liquid Nails Mirror & Metal
Technology	Two-part epoxy	Neutral cure silicone
Result	Rigid	Flexible
Colour	Dries clear	Translucent
Working time	2–3 minutes at 20°C	Skins in 10–15 minutes
Set / tack free	Sets in 5 minutes	Tack free at 45 minutes
Initial bond	30 minutes	—
Full strength	After 16 hours	Cures 2 mm/day; support normally 72 hours
Holds up to	150 kg/cm²	—
Temperature	Up to 60°C	−60°C to 150°C
Packaging	8 mL and 24 mL syringes, 35 mL tube	310 g cartridge

Indicative data only, not intended for the preparation of specifications.

Choose the epoxy for small, rigid, load-bearing joints. A bracket, a fitting, a broken casting, a fabricated part that must not flex. It holds up to 150 kg/cm² when fully cured on a clean, abraded surface, and it reaches maximum strength in 16 hours.

Choose Mirror & Metal for larger areas, exterior work, and anything that has to move. Aluminium expands more than most building materials with temperature, and a long aluminium section bonded rigidly to another will build up real stress in the sun. A flexible silicone adhesive absorbs it. It is also the better option outdoors — the epoxy softens above 60°C and may discolour under UV, while Mirror & Metal has a temperature range of −60°C to 150°C with high UV resistance, suitable for both inside and outside the home, and it is non-corrosive.

Mirror & Metal also has good gap filling on uneven surfaces, which matters if the two aluminium faces do not mate perfectly. The epoxy fills small irregularities but is at its best in a close-fitting joint.

Preparing aluminium — the step that actually decides the result

This matters more here than the choice of adhesive. Aluminium grows a tough oxide layer within moments of any fresh surface being exposed to air, and mill-finish stock usually carries a light oil as well. An adhesive applied to an unprepared aluminium surface is bonded to the oxide and the oil, not to the metal.

1. Degrease first, abrade second, then degrease again. Abrading a greasy surface just spreads the grease into the fresh scratches.
2. Abrade thoroughly. The Araldite surface preparation instruction is to abrade, clean and dry surfaces, and the published strength figure is measured on a clean, abraded surface. A cross-hatched, matt surface gives the adhesive a mechanical key.
3. Bond soon after abrading. The oxide layer regrows. Prepare the surfaces and glue them the same day, ideally within the hour.
4. Anodised or powder-coated aluminium is a coating, not aluminium. Both adhesives claim good adhesion to metals, but the bond will be to the coating and can only be as strong as the coating's grip on the metal beneath. Test on an offcut.

Applying the epoxy

1. Abrade, clean and dry both surfaces.
2. For a syringe, snap out the cap from the plunger and cut the sealed tips at the end of the nozzle. For a tube, pierce each tube with the spike in the top of the cap.
3. Dispense equal parts of both liquids onto a clean disposable surface and mix thoroughly with a spatula. Do not use the plastic blister to mix in. Mix small quantities for maximum working time.
4. Apply the mixed glue to both surfaces of the job, then bring them together. You have 2 to 3 minutes at 20°C.
5. Do not apply undue strain to the bond for 30 minutes. Hold the join with tapes or weights if necessary.
6. Maximum strength is reached after 16 hours. Allow longer in colder weather.
7. Clean up uncured Araldite with acetone.

Applying Mirror & Metal

1. Ensure the surfaces are sound, dry and free from oil, grease and dust.
2. Cut the cartridge, fit the nozzle and cut it to size — approximately 5 mm. Apply with a caulking gun.
3. Apply in strips or beads rather than blobs or dollops, keeping the strips apart so a gap remains between them when the parts are pressed together. Those gaps are what let the adhesive cure, since it draws moisture from the air and cures at 2 mm per day.
4. Press the surfaces together immediately, before the adhesive skins — within 5 minutes.
5. Leave any squeeze-out to cure and trim it, avoiding cutting into the bond.
6. Support the bond until the adhesive cures sufficiently, normally 72 hours.
7. Clean uncured product with mineral turps; cured product needs Selleys Sealant Remover or mechanical action.

Limitations

• Araldite: the bond softens above 60°C, with strength restored when the temperature returns to normal; the product may discolour if exposed to UV; allow longer bonding times in colder weather; will not bond PTFE, polyethylene or polypropylene; no food or drinking water contact approval.
• Mirror & Metal: apply in separated strips, never as blobs; support the bond for normally 72 hours; freshly painted adjacent surfaces should dry for at least 7 days and compatibility on painted surfaces should be tested first; glue lines may be visible through surfaces that are not perfectly opaque.
• Neither is a substitute for a mechanical fixing on a genuinely structural joint.
• If either aluminium part is heavily anodised or coated, test the bond on an offcut before committing.

Common questions about gluing aluminium

Which is stronger?

The epoxy. Araldite Super Strong holds up to 150 kg/cm² when fully cured on a clean, abraded surface. The silicone adhesive gives a flexible bond rather than a high-strength rigid one.

Do I have to abrade the aluminium?

Yes. The Araldite surface preparation instruction is to abrade, clean and dry, and the published strength figure assumes an abraded surface. Degrease before and after abrading.

Which one for outdoors?

Mirror & Metal. It is rated −60°C to 150°C with high UV resistance and is suitable for outside the home. The epoxy softens above 60°C and may discolour under UV.

How long do I have to work with the epoxy?

Two to three minutes at 20°C. Mix small quantities — larger amounts cure faster.

How long before the joint is fully strong?

Araldite reaches maximum strength after 16 hours. Mirror & Metal should be supported for normally 72 hours and cures at 2 mm per day.

Will it corrode the aluminium?

Mirror & Metal is a neutral cure silicone and is stated to be non-corrosive.

What about anodised or powder-coated aluminium?

The bond is to the coating rather than the metal. Test on an offcut before committing.

Does the joint need to be close fitting?

For the epoxy, ideally yes. Mirror & Metal offers good gap filling on uneven surfaces.

Can I use this on a cast aluminium repair?

There is a related question on this site about whether Araldite Super Strength suits a cracked cast aluminium petrol tank. A cast repair also needs the surface abraded back to clean metal, which on an aged casting takes more work than on sheet.

How do I remove it if the job goes wrong?

Acetone on uncured Araldite; mineral turps on uncured silicone. Both need mechanical removal once cured.