Easy fix for cracked plastic

How to fix cracked plastic: Step by step

Replacing damaged plastic can be costly – luckily, learning how to fix cracked plastic is relatively cheap and easy. All you need is the right glue and a little know-how. We cover the basics below.

The basics of fixing cracked plastic

Whether you need to fix broken plastic or fix a hole in plastic, it’s important to use an adhesive that’s compatible with the type of plastic you’re repairing. Checking the manufacturer’s specs and directions are a good place to start, then consider whether the object is rigid or will flex or vibrate during use. This will determine whether you need a flexible adhesive to prevent flexible materials from cracking or an epoxy, which is a thicker, more rigid material better for repairing holes or large gaps.

How to repair plastic step by step

Follow these general steps for repairing broken or cracked plastic:

  1. Grab your materials and find a well-ventilated work area. Protect your tabletop or workspace with a drop cloth or paper covering in case you spill some glue.
  2. Clean the surfaces you’re bonding. You might need to lightly sand very smooth or shiny surfaces so the glue can adhere better.
  3. Apply an activator (if required) and allow to dry according to the manufacturer’s directions.
  4. Apply adhesive and hold or clamp parts together until the glue sets.
  5. Clean up: Remove excess glue from the tip of the tube and re-cap it. Clean-up your work area and wash your hands.

The procedure to fix a hole in plastic is much the same. Make sure the patch piece fits snug into the hole and follow the directions above to glue it in place. If you don’t have a piece to fill the hole, try using epoxy to fill it.

Need to remove excess glue? A damp cloth should do the trick. But if the glue’s already started to dry, or you find dried glue later on, try removing it with acetone. Dab the area with a little acetone and let it soften the glue for a few minutes, then wipe or scrape it away.

How to fix cracked plastic car bumpers

Car bumper busted? Repair it yourself by following these steps:

  1. Remove the bumper and sand the edges of the crack from the back-hand side to increase surface area. Wipe down the front and back with alcohol.
  2. Hold the crack closed (with locking pliers, if you can get your hands on them). Apply masking tape over the surface side of the crack.
  3. Apply adhesive to the back side of the bumper. Use some reinforcing mesh tape embedded in the glue for an extra strong bond.
  4. Once fully dried, remove the tape from the surface side of the bumper. Sand and fill the crack with body filler. 
  5. Once the body filler is dry, sand with 80-grit, then 300-grit paper. Then prime, re-sand, and paint with a specialised car paint matched to your vehicle.
  6. Reinstall the bumper.

Selecting the right adhesive to repair cracked plastic

With so many plastic variations and endless uses for them, it can be tricky choosing the right adhesive to repair your damaged plastic. However, there are great adhesives on the market made specifically for repairing cracked or broken plastic that do a better job than an all-purpose glue.

Our favourite is Loctite Super Glue All Plastics. This specialty super glue is designed for plastics, including the hard-to-bond-to polypropylene and polyethylene. It comes with an activator which you apply first and need to allow to dry for 60 seconds. This allows the adhesive to bond in seconds and dries transparent for close to invisible repairs!

If it’s an epoxy you’re after, Loctite Epoxy Plastic Bonder will do the trick. This formula bonds to most common plastics, including polyvinyl chloride (PVC), Delrin, and acrylonitrile butadiene styrene (ABS). It hardens to a rigid, high-strength bond in about 20 minutes and is resistant to most solvents. It makes quick work of most repairs.