Step 4: Prepare the repair area.

Remove the damaged material. For minor defects, hand sanding with a sanding block or a dual action sander may be sufficient. For laminate repairs, use a saw to cut away the damaged portion. Make sure to remove all damaged material so that the remaining material is structurally sound.

Once the damaged material has been removed, prepare the repair area by grinding or sanding to facilitate adhesion of repair materials. Remove all dust, oils, waxes and other contaminates. Keep the repair area as small as possible to minimize finishing work. Mask off the repair area to prevent damage to surrounding areas.

Step 5: Measure and mix repair materials.

It’s critical to accurately measure all repair material quantities, including resins, gel coats, patch aids and peroxide initiators. These materials must be used within specified ratios to perform properly and allow completion of a successful and durable repair. The preferred measuring method is by weight. Low-cost scales can be purchased from local pharmacies, laboratory/hospital supply firms or scientific apparatus suppliers. The next best method is to measure by volume using graduated cylinders.

Many repairs are small and require small amounts of patching materials. Be sure to prepare materials in quantities that can be measured accurately even if the majority of the material is discarded. It is cheaper to discard excess material than to redo a repair because of inaccurate measurement.

For gel coat repairs, patch aids are recommended. Patch aids are resin- or monomer-based solutions that improve the working properties of gel coat when patching. They lower viscosity for easier spraying and reduced “orange peel” – or uneven surface texture. This reduces the time required to finish the repair. Patch aids also accelerate cure so that patches can be finished sooner and reduce surface tackiness for better sanding. Thinning gel coat with solvents such as acetone is not recommended. Solvents slow the cure of the gel coat and can result in off-color, dull and/or hazy patches.

Step 6: Apply repair materials.

For laminate repairs, use a roller or squeegee to pre-wet the glass. If working from the laminate backside, create the needed contour using cardboard or aluminum covered with cellophane prior to applying the glass to the repair area. If working from the front side, make a plug from cardboard with wires through the center, apply the glass to the plug and insert through the hole. Use the wire to secure the plug against the laminate until the resin cures. Remove air voids with a squeegee or roller. Allow the resin to cure thoroughly before proceeding.