Reaching for whatever glue is closest to hand is one of the most common reasons a bond fails. A super glue that grips metal in seconds can slide right off certain plastics, and a wood glue that holds two planks for decades may do nothing useful on a sheet of aluminium. The surface you are bonding matters just as much as the adhesive itself.
This guide breaks down how to match the adhesive to the material, so your bond holds the first time.
Why the surface decides the adhesive
Every material has a property called surface energy, which is essentially how easily a liquid adhesive can spread out and grip it. High surface energy materials such as metals, glass and many engineering plastics let adhesive flow into every microscopic dip, which creates a strong bond. Low surface energy materials such as polypropylene and polyethylene repel the adhesive, so it beads up instead of wetting out.
Porosity matters too. Wood and other porous surfaces soak up adhesive, which is helpful with some glues and wasteful with others. Get the surface type right and choosing the adhesive becomes far simpler.
Bonding plastic
Plastic is the trickiest of the three because the category covers everything from easy-to-bond ABS to almost unbondable Teflon.
Easier plastics, including ABS, polycarbonate, acrylic, PVC and most rigid moulded parts, bond well with cyanoacrylate (super glue) for small joints or two-part epoxy for structural strength. Hard cases such as polypropylene (PP), polyethylene (PE) and HDPE, the materials used in many tubs, crates and chemical containers, resist almost everything. For these, you need a cyanoacrylate sold with a dedicated plastic primer, or a mechanical solution such as a high-bond double-sided tape that grips through sheer surface contact rather than chemical wetting.
If you are not sure which plastic you have, a quick way to narrow it down is the water test. Water beads tightly on low surface energy plastics like PP and PE, which signals you will need a primer or tape rather than ordinary glue.
Bonding metal
Metal is forgiving once it is clean. The most common cause of failure is not the adhesive but the thin film of oil, grease or oxide left on the surface. Wipe the area with isopropyl alcohol and lightly abrade shiny metal before bonding.
For strong, rigid joints, two-part epoxy is the workhorse. It fills small gaps, resists chemicals and bonds metal to metal, metal to wood and metal to most plastics. For metal parts that flex, vibrate or expand and contract with temperature, a polyurethane adhesive or a structural double-sided foam tape absorbs that movement instead of cracking under it. Cyanoacrylate works for small, well-fitting metal parts that will not take much stress.
Bonding wood
Wood is porous, so it drinks in adhesive. For wood-to-wood joints, a quality PVA wood glue is hard to beat: it soaks into the fibres and, once cured, the joint is often stronger than the surrounding timber. Clamp the pieces while it sets.
When you are joining wood to a different material, switch to polyurethane adhesive. It cures by reacting with moisture, foams slightly to fill uneven gaps, and bonds wood to metal, stone and many plastics. For sticking laminates or veneers across a large wood surface, a contact adhesive gives an instant, even bond without clamping.
Quick reference: adhesive by surface
| Surface | Best first choice | Also works | Watch out for |
| Rigid plastic (ABS, PVC, acrylic) | Cyanoacrylate or epoxy | High-bond double-sided tape | Test a small area first |
| PP, PE, HDPE plastic | Cyanoacrylate with plastic primer | High-bond double-sided tape | Ordinary glue will not hold |
| Metal to metal | Two-part epoxy | Cyanoacrylate for small parts | Degrease and abrade first |
| Metal to wood or plastic | Polyurethane adhesive | Epoxy | Allow for movement and expansion |
| Wood to wood | PVA wood glue | Polyurethane | Clamp while curing |
| Laminates onto wood | Contact adhesive | Polyurethane | Bonds on contact, align carefully |
Surface prep makes or breaks the bond
No adhesive performs to its rating on a dirty surface. Before you bond anything, clean off dust, oil and old residue, then dry the surface fully. Lightly roughen smooth or glossy surfaces so the adhesive has more to grip, and for stubborn plastics reach for a primer designed for low surface energy materials.
The Singapore climate factor
Local humidity changes how some adhesives behave. Cyanoacrylate actually cures faster in humid air, which can leave less time to reposition a part. Moisture-cure polyurethanes also set quicker. Epoxy is more stable, but its mix ratio and cure time should still follow the label. Store adhesives sealed, cool and out of direct sun, because heat and moisture shorten shelf life. Browse MOPI’s full range of glues and sealants to match a product to your project, or consider our double-sided tape when you want a clean, clamp-free bond.