A fiberglass swimming pool can last for many years, but eventually the pool may begin to develop cracks and show other signs of wear, such as blisters and bubbles. The swimming pool steps receive a lot of usage. Their design may have some inherent structural weaknesses, which makes them even more prone to developing cracks. A do-it-yourselfer can repair fiberglass pool steps, but it's highly unlikely that you can find an exact match of colors for the swimming pool repair unless the lining is white.
Drain the pool and allow the surface to dry completely. Use an orbital sander to remove the old surface coating on the area you want to repair. If you're removing the entire surface of the steps, use a sand blaster to make the job go faster. Or if you prefer, remove the original coating by hand with sandpaper. Remove all the debris.
Cut away the cracked areas, using the handsaw. Extend the cut slightly beyond the crack line to provide a smoother edge to repair. Mix the putty in the fiberglass repair kit and use it to fill the cracks. Smooth it over with a putty knife. Allow it to dry, then sand the rough edges.
Put masking tape around the perimeter of the area where you removed the original fiberglass coating. Coat the steps or the area on the steps you're fixing with a fiberglass solvent that helps the coating adhere to the pool's surface. Use a long-handled paint roller to apply the first coat of fiberglass gel coat. Stay within the boundary of the masking tape.
Lay down a layer of fiberglass cloth, if that's the type product you chose for your repairs. Eliminate any air bubbles in the cloth. Coat the cloth with another layer of gel coat. Other products have the fibers in the gel coat itself. Simply apply a second coat of the fibered gel coat when the first layer is dry. Allow all layers to dry completely.
Sand the surface lightly. Wipe away the residue. Apply a finishing coat to the area you're fixing and allow the entire project to dry according to the repair kit's recommendations. Remove the masking tape. Do not get the fiberglass wet until the curing process is complete.