Old fiberglass bathtubs can wear down in certain places. While an old fiberglass tub starts to lose its watertight seal, you need to either repair it or replace it. That is, if water starts to seep through the tub, you can have serious issues with the frame of your house if you don't seal it. So, if you have a limited budget, you probably just want to patch and repair your holes so you can start to use your bathtub again.
It is actually very easy to patch a fiberglass bath enclosures to make it waterproof again. This article focuses on how to use a fiberglass patch kit to create a lasting patch that will not leak water. Importantly, this article does not discuss how to refinish and repaint fiberglass to make it look brand new. That is an entirely different process that you can do after your tub is patched.
Patching fiberglass is always easier if you use a fiberglass patch kit. These are ideal if you don't already have any of fiberglass patch the materials. Not only they come with the actual fiberglass cloth, they also include resin, liquid hardener, a mixing stick, and a mixing tray. In addition to these things, you also need to have a fiberglass sandpaper and masking tape.
Applying the Patch
The actual application of fiberglass cloth is pretty basic if you properly prepare it. First, you want to cut your fiberglass cloth to the right size. Make sure that it is wider than the damaged area by several inches on each side. It should overlap onto the fiberglass.
Then, you should trace the cloth on to the actual tub surface. You can use the sandpaper to lightly scuff up the fiberglass within the area that you traced. When the surface is rougher, the resin will stick better to it. Now, you basically place the cloth over the area and apply the resin on top of it.
Sanding the Fiberglass
You can spread the resin on as thick as you like, but you will need to come back once it is dry to sand it down and make it smooth, flat, and free of lumps. If you apply the fiberglass on too thick, you will need to spend more time sanding.
All in all, once your fiberglass is patched, it's not necessarily going to look beautiful, but the surface is going to be waterproof once again, so you can start to use your bathtub and shower like normal.