As part of camper living, things regularly break. For a while now I have been suffering with a crack in the floor of my shower.

I’ve patched it several times already with crack sealers, epoxies, construction adhesives, and silicone. They each worked alright, until they started to peel or fail. Finally, the crack started to grow and I had to take more decisive action.

Today’s project was to patch this once and for all, with Bondo.

Bondo is some pretty amazing stuff. It is a two part mix - a fiberglass resin and a hardener. You mix the two together, and it creates an exothermic reaction that makes a very hard waterproof substance that sticks to whatever it hardens against.

The first step is to clear off anything that is between the resin and the surface you are patching. I started with a plastic scraper so as to not damage the floor much, but quickly advanced to using my trusty pocketknife. D2 steel is up for most any challenge…

You overlay the area in question with fiberglass cloth. The purpose of the cloth is to add strength and give structure to the liquid resin - something for the liquid to bond to. Similar to putting rebar inside of concrete in a way, or cotton with epoxy.

The resin spreads pretty easily and causes the fiberglass cloth to calm down and stick to wherever it’s supposed to be. Some of the frayed edges of the cloth stuck up through the surface, but otherwise it self-leveled pretty smooth.

The resin started hardening pretty quickly. The reaction is exothermic, so I could feel some pretty significant heat coming from the bottom of the cup that I was using as my mixing tray. If I could have gotten to it in time, I could have used ascetone or lacquer thinner to clean the brush, but I didn’t have any on hand.

After two hours, the patch had completely hardened. It had some pretty significant bumps and lumps that needed to be dealt with though.

Nothing like the handy random orbit sander to deal with that problem. It made pretty quick work of any roughness in the surface. I didn’t take it all the way down to flat, as I am more concerned about preventing future cracking at this point than appearance. Maybe someday I’ll sand it again and paint it.

In the end, it is now a nice waterproof patch. For such a satisfying result, the amount of work was pretty minor. Bondo you get an A+!