Things You'll Need
Acetone or nail polish remover
A chipped windshield or small crack in a window pane can be irritating and even dangerous. Epoxy is a natural choice to repair glass due to its strong bonding and adhesive properties, and because it can be produced in a clear form. Epoxy is a co-polymer—it's formed from two chemicals, usually referred to as a resin and a hardener. When the two chemicals are mixed, polymerization takes place, or what's commonly called "curing." This process can be controlled by temperature and time, allowing for a wide range of applications. A chipped windshield is a common candidate for epoxy repair.
Clean the glass thoroughly. Use a detergent soap and then dry thoroughly. The chip or crack to be repaired should not exceed an inch and a half. Anything larger should be handled by a windshield repair expert. You may need a new windshield if the damage is too large to safely repair.
Mix the two epoxy components together. Read the directions to determine the ratio of the resin and the hardener, and to know how long the cure time is.
Spread a small amount of epoxy into the hole or crack with a putty knife. Have a razor blade and a rag soaked with acetone (nail polish remover will work) on hand. Use the putty knife to work the epoxy into the blemish and to smooth the area and remove excess epoxy. Use the rag or razor to remove any left-over epoxy before it dries.
Insert a piece of chipped-out glass, if you have it (and if it is large enough to make the effort worthwhile). Tiny chip holes or cracks can be filled with epoxy only. After inserting the chipped piece, excess epoxy will be squeezed out by the presence of the glass chip. Remove the excess and smooth the area so it is flush with the windshield or window. Make sure that the curing rate for the epoxy is long enough to allow you to spread the epoxy, insert the glass chip and smooth out the repair.
Let the epoxy cure. Read the cure rate on the label (12 to 24 hours is typical). Allow the epoxy to set up before removing any imperfections with a razor and acetone.
Use glass cleaner to polish the glass windshield/window and check the repair.
Choose a two-part, clear epoxy. It may or may not be labeled as being designed for glass repair. You should fill in small chips even if they are not readily noticeable or in the driver’s field of vision. Repairing a small crack will prevent it from spreading and becoming a larger, more dangerous crack.
Larger or deep chips can be repaired with generally the same methods, but with the additional first step of drilling a hole through the first layer of glass and sucking the air out from between the glass layers with a vacuum-suction tool. If you have never used a drill and vacuum-suction machine on a windshield, it may be a good idea to have a professional do this type of repair.