Does epoxy work on a cracked plastic bumper?

Not on polypropylene. Standard epoxy beads up on PP and pops off when the cover flexes. Most modern bumper covers are PP (recycling code 5). Use a primer kit on a small dry crack, or weld a split.

Can I drive after gluing a bumper crack?

Only if the repair was a small cosmetic crack on a tab or flare and the kit has fully cured. A split in a mount or beam is a weld or a new cover. A glue-only structural patch can come off in traffic.

The rubber strip came off the bumper — same glue?

No. That is a plastic-to-rubber job. Use contact cement on both faces. The primer kit is for a crack in the PP cover, not a peeling rubber lip.

How do I know the bumper is PP and not ABS?

Look for recycling code 5, a waxy feel, and a hot pin that melts instead of charring. ABS is harder, often coded 7, and solvent cement can bite it. If acetone dulls the surface, this guide is the wrong one.

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Guide

Repair a cracked PP bumper

You cannot glue a polypropylene bumper the way you glue ABS. A small dry crack on a tab or flare can take a two-step plastic primer kit. A split in the bumper beam or a crack that opens when you flex the cover needs plastic welding — or a new cover. Ordinary epoxy peels off PP.

Polypropylene (PP)

This task involves: Outdoor exposure, Flexing or movement

Best Glue for This Repair

Plastic bonding kit (primer + CA)

The activator pen raises PP's surface energy so the cyanoacrylate can grip a small, dry, close-fitting crack. Untreated PP sheds every ordinary glue.

Extra prep

Wipe the surface clean, then coat both faces with the system's activator pen and let it flash off before the adhesive.

Not for: Outdoor exposure, Gap or poor fit

Reviewed and adjusted by an editor.

Why Plastic bonding kit (primer + CA) Works Here

The problem plastic. Its waxy, low-energy surface sheds ordinary glues — epoxy, super glue, and wood glue all peel off. It needs a specialty primer system or a mechanical fix.
The primer pre-treats PP's waxy surface so the adhesive can grip — ordinary glues can't.
Wipe the surface clean, then coat both faces with the system's activator pen and let it flash off before the adhesive.
The activator pen raises PP's surface energy so the cyanoacrylate can grip a small, dry, close-fitting crack. Untreated PP sheds every ordinary glue.

How to do it

Repair a cracked PP bumper: Step by Step

A glued bumper is not a crash repair

Do not treat a glue patch as the only thing holding a bumper on the car. A failed cover can drag, block a light, or come off in traffic. Primer solvents and a welding iron also burn skin and irritate lungs. If the crack is in a beam, mount, or you feel unsure, stop and weld or replace the cover. Seek medical care if you burn yourself, get solvent in your eyes, or have trouble breathing.

Confirm the cover is PP — recycling code 5, waxy feel, a hot pin that melts rather than chars. If the crack is in a beam, a mount, or opens when you flex the cover, stop and weld or replace. Do not glue it.
For a small dry crack on a tab, flare, or splash shield only: wash, dry, and scuff both faces. Wipe with isopropyl alcohol and let it flash.
Coat both faces with the kit's primer pen, wait the time on the card, then apply the matching cyanoacrylate and hold the crack shut.
Leave the part still until the kit's full cure. Do not flex the cover or wash the car early.
A long split is a plastic-weld: heat and a PP welding rod, or a bumper shop. A rubber lip coming off the cover is contact cement, not this kit. If you can see daylight through a mount, do not drive on it.

Conditions

When to Use a Different Glue

Primer plus cyanoacrylate is only for a close-fitting dry crack. A bumper that has to survive another parking-lot hit is a weld. A rubber lip coming off the cover is a plastic-to-rubber job, not this crack repair. Do not drive on a glue-only structural repair.

Avoid

Glues to Avoid for This Repair

Avoid
2-part epoxy
Standard epoxy beads up on polypropylene and pops off the first time the cover flexes.

Articles

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Questions

Common Questions About This Repair

Does epoxy work on a cracked plastic bumper?: Not on polypropylene. Standard epoxy beads up on PP and pops off when the cover flexes. Most modern bumper covers are PP (recycling code 5). Use a primer kit on a small dry crack, or weld a split.
Can I drive after gluing a bumper crack?: Only if the repair was a small cosmetic crack on a tab or flare and the kit has fully cured. A split in a mount or beam is a weld or a new cover. A glue-only structural patch can come off in traffic.
The rubber strip came off the bumper — same glue?: No. That is a plastic-to-rubber job. Use contact cement on both faces. The primer kit is for a crack in the PP cover, not a peeling rubber lip.
How do I know the bumper is PP and not ABS?: Look for recycling code 5, a waxy feel, and a hot pin that melts instead of charring. ABS is harder, often coded 7, and solvent cement can bite it. If acetone dulls the surface, this guide is the wrong one.