Repair guide
How to bond an ASA part to an ABS housing outdoors
ASA and ABS are closely related plastics, but outdoors the joint has to survive sun and thermal movement, which is why a flexible MS polymer usually outlasts a rigid bond between them.
The short answer
Abrade both plastics, wipe with isopropyl alcohol, and bond with an MS polymer adhesive. ASA exists because ABS degrades in sunlight, so this pairing almost always means one part is outside. An MS polymer stays flexible, is stable in UV and copes with the two parts expanding at slightly different rates in the sun, which is what cracks a rigid bond line over a season or two.
- Difficulty
- Moderate
- Time needed
- 20 minutes work, 24 to 48 hours cure
- What you need
- MS polymer adhesive and caulking gun, 180 grit abrasive paper, isopropyl alcohol, low tack masking tape, clamps or tape, dry cloths
ASA is ABS with the butadiene replaced by an acrylate rubber, which is what gives it real UV resistance. Chemically the two are close enough that solvent welding is possible, and for an indoor, static joint that is a legitimate and very strong option.
Outdoors the calculation changes. A solvent weld is rigid, and a rigid joint between two mouldings that are heated unevenly by the sun concentrates all the movement at the bond line. It also does nothing to protect the ABS side, which will chalk, yellow and get brittle in UV whatever you glue it with. If the ABS part is going to be permanently exposed, the sensible answer is to shade it, paint it or replace it with ASA, not to glue it better.
MS polymer gives up some ultimate strength in exchange for elasticity and weather stability. For trim, housings, brackets and enclosure parts, that is the right trade. For a structural joint that must not move, use a structural acrylic instead and accept that it needs a well controlled bond line.
Both plastics take a bond much better when abraded. Moulded surfaces are smooth and 3D printed surfaces carry a thin skin that abrasion removes.
Step by step
- Dry fit and mark the joint position with low tack tape.
- Abrade both bonding faces with 180 grit until the shine has gone.
- Wipe both with isopropyl alcohol and let it evaporate. Do not use acetone on either part.
- Apply MS polymer to one face in a continuous bead, keeping back from the visible edges.
- Press the parts together and slide them a couple of millimetres to spread the adhesive.
- Tape or clamp lightly so the joint cannot move, but do not squeeze the adhesive out.
- Tool any squeeze out with a dry finger before it skins.
- Leave 24 hours, and 48 before it sees weather or load.
What to avoid
Do not solvent weld an outdoor joint between these two. It is strong but rigid, and the sun will find the bond line.
Do not leave a bare ABS part in permanent sunlight and expect the joint to be the thing that fails. The ABS goes first.
Do not clean either plastic with acetone. It attacks ABS quickly and marks ASA.
If the joint is structural or carries any load, a flexible adhesive is the wrong tool and you should be looking at a structural acrylic or a mechanical fixing. Uncured MS polymer is hard to remove from a moulded surface, so mask before you start.
The full bonding guide
Everything about gluing ABS to ASA
Last reviewed 13 September 2026.