Things You'll Need
When the plastic casing for an object gets cracked, many people simply replace the object. Plastic, however, is malleable, and you can often repair it by melting it., With a little practice, a smooth weld can be achieved, although the repaired object may not look as good as new. Plastic welding does not have to be limited to repairs -- the same skills can be used for artistic projects. If you already have a soldering iron, you don't need to purchase a plastic welding kit; you can start plastic welding right away.
Clean the plastic with soap and a degreaser, if necessary. Sand down the edges to be welded just enough that they are not jagged.
Plug the soldering iron in and allow it to heat up for a few minutes.
Push the two pieces of plastic together. Run the soldering iron tip back and forth over the seam to partially melt the plastic together. Adjust the pieces of plastic to get them in the proper places while the material is hot and soft.
Add more plastic onto the seam to strengthen it by laying smaller pieces of plastic along the seam. Melt them fully by pressing on the small pieces with the soldering tip until they become liquefied. Spread the melted plastic evenly along the seam with the soldering tip.
Go over the seam and surrounding area with the soldering iron using fast, smooth strokes to create an even, smoothly welded surface.
Experiment on some scrap plastic first to know how long to keep the soldering iron on a particular point. Every type of plastic will melt at a slightly different rate.
Fumes from melting plastic are noxious. Perform this procedure in an open area outdoors, and wear a protective mask.