A cracked taillight is usually cause for replacement but there are a couple ways you can repair them if you wish to take the time to do so. Repairing a taillight is relatively easy and fairly quick, depending on the method of repair you choose. Small cracks and chips can be replaced but significant damage will require you to replace the taillight. Repairing a taillight can be especially important if you are driving an older, or classic, vehicle and parts are not easy to come by. Driving with a cracked or broken taillight not only could be dangerous to you or other drivers but you may also get a ticket for it.
Taillights become damaged from a wide variety of things but small chips and cracks are usually the result of rocks or debris being kicked up from the road. The process to repair a taillight is simple and should work for any crack or chip that is the size of a quarter or smaller. If the taillight is missing pieces or some of the plastic has been broken off a repair will not be possible. The best way to repair a taillight is to purchase a taillight repair kit from an auto supply or hardware stone. Some taillight repair kits include small repair panels or plastic tape but the best ones have a resin like compound inside of them.
To begin you should start by removing the piece you wish to repair from the vehicle. Open your repair kit and remove the plastic film inside. This film is then attached to the inside of the plastic taillight over the hole, crack or damage. It is important to note than the film provided in a repair kit will only work on a smooth surface. If the interior of the light is rough or bumpy it is recommended that you use a clear, cellophane tape instead.
Most repair kits contain a material to mix in order to repair the damage. Like an epoxy this material requires you combine two ingredients in order to activate the chemical process between them. Once the materials are mixed you will have a certain amount of time in order to use the repair compound before the material becomes worthless. This will be detailed in the repair kit instructions but you should have plenty of time to apply the repair mixture so don't panic or rush. Mix the repair compound per the instructions included in the kit.
Apply the repair compound with a syringe provided in the repair kit. You should be extremely careful in applying the mixture not to overflow beyond the area you wish to repair. Small repairs may only require a few small drops. You can always apply more but it is difficult to take material away once it is on the taillight.
Allow the material to dry. Once dry the repair will appear darker than the surrounding glass of the taillight but it will lighten up as it dries. After the material is completely dry re-install the taillight and you are finished.