Best Adhesive To Bond Aluminium to MDF
What is the best adhesive to bond aluminium to plywood or MDF?
Selleys recommends one of two products for bonding aluminium to timber-based sheet materials: Selleys 3 in 1 or Selleys 650FC Fast Cure Adhesive Sealant.
Both are flexible sealant-adhesives rather than rigid glues, and that is deliberate. Aluminium and MDF expand and contract at very different rates, so a rigid bond line between them is a bond line under permanent stress. A product with real movement capability absorbs that difference instead of transmitting it to the joint. 650FC is a premium fast-cure multipurpose flexible adhesive sealant using advanced hybrid technology, and it is free of isocyanates and solvents, for interior and exterior bonding and sealing.
Comparing the two
| Property | Selleys 3 in 1 | Selleys 650 FC |
|---|---|---|
| Technology | Moisture curing silyl-modified polymer (SMP) | Silane modified polymer |
| Colour | White | Grey, black, white |
| Packaging | 480 g cartridge | 300 mL cartridge or 600 mL sausage |
| Tooling time (23°C, 50% r.h.) | ~15 minutes | — |
| Skin time (23°C, 50% r.h.) | 15 to 30 minutes | 20 minutes |
| Cure rate (23°C, 50% r.h.) | 3 to 4 mm / 24 hrs | 2.5 mm / 24 hrs |
| Movement capability | ±20% | ±20% |
| Shore A hardness | 40 ± 5 | 40 ± 5 |
| Elongation at break | >250% (DIN 53504) | >500% (ASTM D412) |
| Tensile strength | 1.3 MPa (DIN 53504) | 2 MPa (ASTM D412) |
| Bond strength on timber (7 days) | — | >1.4 MPa |
| Application temperature | 5 to 30°C | 5 to 35°C |
| Service temperature | 0 to 70°C | −40°C to +70°C, brief points at 100°C |
| Paintable | Yes | Yes, once cured |
Indicative data only, not intended for the preparation of specifications.
Which one to choose
Choose 650FC for anything structural-feeling, outdoor, or in more than one colour. It has the higher tensile strength at 2 MPa, publishes a specific bond strength on timber of greater than 1.4 MPa after seven days, and comes in grey, black and white in both cartridge and sausage. Its service range runs from −40°C, so an unheated garage or an outdoor application is within scope.
Choose 3 in 1 for indoor work where you also want gap filling. It is a single white product that works as construction adhesive, waterproof sealant and no-shrink gap filler, with zero slump and a slightly faster cure at 3 to 4 mm per 24 hours. Its service temperature starts at 0°C, so it is the less appropriate of the two for anything that will freeze.
What the movement figure means here. Both are rated ±20%. On a bonded panel that is not a joint-width figure so much as an indication that the cured adhesive stays elastic — it will accommodate the differential movement between an aluminium face and an MDF substrate as the room's temperature and humidity change, rather than shearing at the interface.
How to apply it
- Make sure both surfaces are clean, dry and free from dust, grease, release agents and loose or crumbling material. Aluminium is usually supplied with a light oil film — degrease it.
- Check the temperature. Apply between 5 and 35°C for 650FC, or 5 to 30°C for 3 in 1. Do not apply below 5°C.
- Cut the cartridge or sausage, fit the nozzle and load a good-quality gun.
- Apply in lines or beads across the prepared surface, then press the parts firmly together so the adhesive spreads and makes contact across the bond area.
- Use a suitable fixing — clamps, weights or temporary fasteners — until the adhesive has cured.
- Leave it to cure at 2.5 mm per 24 hours (650FC) or 3 to 4 mm per 24 hours (3 in 1). A closed bond line between two non-porous-ish faces cures from the edges inwards, so allow generously.
Limitations to be aware of
- Both require atmospheric moisture to cure. A very thin, fully closed bond line between an aluminium sheet and a sealed MDF face gives the adhesive little access to air. Use beads rather than a continuous full-coverage film so moisture can reach the adhesive.
- Do not apply below 5°C air or substrate temperature.
- Neither is recommended for continuous submersion or below water line use.
- Do not apply 650FC in the presence of curing silicone or polyurethane sealants, as the cure may be affected.
- Avoid contact with solvent cleaners during cure, which will affect the cure.
- Do not use for structural glazing.
- Both may affect the drying of alkyd or oil-based paints.
- White sealant may yellow slightly with age and exposure to the sun.
- MDF is not a weatherproof material in its own right. The adhesive being exterior-rated does not make an MDF panel exterior-rated.
Clean up
Spills and tools clean up with mineral turps before the product cures. Cured product can only be removed mechanically, so deal with squeeze-out on a visible aluminium face immediately.
Common questions about bonding aluminium to timber sheet
Will an epoxy work instead?
An epoxy such as Araldite Super Strong gives a rigid bond, and Selleys does not nominate it for this pairing. The flexible sealant-adhesives are recommended here because aluminium and MDF move at different rates.
Does it work on plywood as well as MDF?
Yes. Both products list soft wood and hardwood among the common building materials they adhere well to, and Selleys recommends them for bonding aluminium to timber materials generally.
Do I need a primer?
650FC generally has good adhesion without priming to the common building materials listed. In some instances a primer may be required, and a pre-test to confirm adhesion is recommended.
Can I paint over the bond?
Yes. 650FC can be painted once cured, and 3 in 1 is paintable. With solvent-based paints, prime first with a water-based primer.
How long do I need to clamp?
Until the adhesive has cured. Skin time is 20 minutes for 650FC and 15 to 30 minutes for 3 in 1, but skinning is not curing — hold the parts with a suitable fixing rather than relying on initial grab.
Is the anodised or powder-coated finish a problem?
Both products claim broad primerless adhesion to metals, but a coated aluminium face is a coating, not aluminium. Pre-test adhesion on an offcut before committing.
Which is stronger?
650FC, on the published figures: 2 MPa tensile strength against 1.3 MPa for 3 in 1, and a stated timber bond strength above 1.4 MPa after seven days.
Can I use it outdoors?
650FC is intended for indoor and outdoor bonding and sealing and is rated from −40°C. 3 in 1 is listed for interior and exterior use with a service temperature starting at 0°C.
What size do I need?
3 in 1 comes as a 480 g cartridge. 650FC comes as a 300 mL cartridge or a 600 mL sausage, which needs a sausage gun.
What is the best adhesive to bond aluminium to MDF?
Aquadhere Durabond is recommended as the ideal adhesive for bonding aluminium to MDF. It is a solvent-free, moisture-curing polyurethane wood glue specifically formulated to bond wood and wood-based composite materials like MDF to almost any surface, including metals.
What are the key advantages of using Aquadhere Durabond for this application?
Aquadhere Durabond effectively bonds MDF to metal surfaces including aluminium, creates a strong and durable bond with excellent water resistance, is suitable for both interior and exterior applications, is heat resistant up to 140°C, expands slightly as it dries (useful for gap filling), and can be sanded, painted, and stained after curing.
How long does Aquadhere Durabond need to be clamped, and how long until it fully cures?
Aquadhere Durabond requires a clamp time of approximately 4 hours, with full cure achieved in up to 24 hours depending on humidity and material porosity.
What steps should be followed when applying Aquadhere Durabond to bond aluminium and MDF?
First ensure both aluminium and MDF surfaces are clean, dust, and grease-free. Sand or roughen the aluminium surface for better adhesion. Apply a thin layer of adhesive to one surface only since the glue expands as it cures. Assemble the materials within 10 minutes, clamp firmly for approximately 4 hours, and allow 24 hours for maximum strength.
How should the aluminium surface be prepared before bonding with Aquadhere Durabond?
For optimal results with smooth aluminium surfaces, the surface should be sanded or roughened before bonding to improve adhesion.
How should a very dry, porous MDF surface be prepared before applying the adhesive?
Very dry porous surfaces like MDF should be wiped with a damp cloth for 1 minute before bonding, since the adhesive requires moisture to cure properly.
Can Aquadhere Durabond be painted or stained after it cures?
Yes, after curing, Aquadhere Durabond can be sanded, painted, and stained.
Is Aquadhere Durabond suitable for outdoor use?
Yes, Aquadhere Durabond is suitable for both interior and exterior applications and offers excellent water resistance.