Plastic automobile skirts receive a great deal of abuse due to their close proximity to the road. However, plastic skirts prevent more serious and expensive-to-repair damage to the car's body, which is why they are found on many automobiles. Cracks are one of the skirt's most common problems. Replacement costs for automobile skirts can be high. If the vehicle is an older model, finding a replacement skirt can be extremely difficult. Use a few simple techniques and epoxy resin to repair, rather than replace damaged plastic skirts.
Wash the skirt to be repaired thoroughly. Epoxy resins will not work if there is a barrier of dirt or grease between the resin and the surface the resin is bonding to. Use two teaspoons of concentrated liquid washing powder to 473ml of hot water. If there is a thick layer of grease, use 4 teaspoons of concentrated liquid washing powder to 473ml of hot water. After washing, allow the skirt to dry completely before proceeding to step two.
Sand the area around the crack by hand, using 320-grit sandpaper. Sand at least 4 inches on all sides around the crack to create a rough surface for the resin to bond to. Wipe down with a clean rag to remove any sanding debris.
Cut two pieces of fibreglass mat cloth at least 2 inches larger than the crack in all directions. Fibreglass mat is made up of loosely placed strands of fibreglass, spread out in all directions. It is designed to form to any shape and becomes rigid when resin is applied to it. If there is more than one crack, cut two pieces of mat cloth for each crack.
Mix the resin thoroughly in a plastic cup. Do not use wax lined paper cups because the wax will melt as the resin heats up during the mixing process. Epoxy resins comes in two parts. One part is the actual resin while the other part is the hardener. Use a 1-to-1 epoxy resin, which uses equal parts of resin and hardener. Mix only enough resin to repair one crack at a time. Most epoxy resins have a gel time of 15-to-20 minutes which means the resin starts to coagulate or become "jelly-like" within that time.
Brush on a thick layer of mixed epoxy resin to the area around the crack. The area covered by the resin should be a little larger than the cut pieces of fibreglass. Apply one cut piece of fibreglass to the resin covered area. Smooth the fibreglass out, apply another thick layer of resin on top of the fibreglass and allow the resin to dry for at least 6 hours.
Sand the area covered with resin and fibreglass lightly by hand, using 320-grit sandpaper. Epoxy requires sanding in between individual coats of resin. Wipe the sanding debris off with a rag. Apply another thick coat of resin on top of the sanded area and apply the second piece of cut fibreglass cloth. Smooth out the fibreglass and apply a final coat of resin to the fibreglass. Allow 24 hours drying time.
Wipe down the plastic skirt thoroughly with a rag. Mount the skirt back on to the bumper and the project is complete.
If there is a large gap in the crack, that gap can be filled in with cut up pieces of fibreglass and resin. Slice the fibreglass up with a sharp utility knife and mix it in with the resin.
Wear a disposable painter's mask when sanding resin and fibreglass, which can lodge in the lungs and cause long term damage without respiratory protection.