Power at Work: A primer for simple fibreglass repairs

Wednesday, December 19, 2007

Some tips to help you do your own repairs with materials readily available at the local hardware or auto-body supply shop

by KEITH BERGLIND

There was a time when I tried to repair most things with glue, screws and bolts with nuts and washers.

Now I find that fibreglass methods can be used both to repair things and to create whole new parts. In one recent repair project, I had to make a plaster mould for a missing piece of a fibreglass car body and then attach the new piece using fibreglass. So, the purpose of this story is to encourage other handy persons to go to the local hardware or auto-body supply shop and stock up on the basic fibreglass materials. I get most of my stuff from the local Canadian Tire store. The resin and hardener, with a mixing tray, comes as a kit or individually. You also need some fibreglass cloth, plastic table knives and plastic gloves.

For today's project, I am attaching two wooden blocks to the back of a seat cushion support for my back-hoe. Originally, it was only pop-riveted to a top bar, but I wanted to attach it to the frame in the middle, without having bolt heads behind the cushion.

So I decided to 'glass' two pieces of hardwood to the back and then use screws from behind.

As usual, good preparation makes for a better job, so I used a disk grinder to grind off any paint and dirt on the repair area. Safety is always a concern, so goggles, face mask and rubber or plastic gloves are a must. I use lots of the plastic gloves that are used by food handlers. They're cheap and talcum powder makes them easier to remove.

It makes sense to pre-cut all the pieces of glass cloth and/or mat. I used to cut and glue, piece by piece, until my scissors froze solid with hardened resin. For this project, I've added a piece of fibreglass mat on the wood, just to build up the layer of fibreglass.

The first instructions I ever received told me to soak each piece of cloth in the dish of mixed resin. By the time I got past the first piece, my hands were wet with resin and there were drips and drops everywhere.

Then I smartened up. The easy way is to wet the surface with the resin mixture, which is simple to do with a plastic spoon or a metal putty knife.

Then lay the dry cloth on the wet surface and rub it into the resin base. Use a dry stick or your fingers, if you're wearing gloves. This is easier and makes for a much smoother cloth surface. Once you're satisfied with the placement of the cloth or mat, pour a thin layer of mixed resin over the whole surface and trowel it into the cloth, leaving a smooth surface.

Here's a special trick I've learned.

A friend who made his fortune repairing and painting boats told me to wet the primary surface with a thin layer of acetone and resin (no hardener). Then lay down the cloth and pour and spread the resin mixture all over the surface of the cloth. I have tried that trick with today's project, so we'll see at the end how well it works. The idea is to reduce the amount of handling of cloth wet with resin mixture.

Time gets to be critical once you've added the hardener to the resin. If you add too much hardener on a very hot day, the mixture will turn hard really quickly. So it pays to pre-cut all the pieces and lay out the cloth, as above, then mix and pour the mixture over the laid-down cloth.

If you have a flair for mad chemistry, experiment with different mixtures.

I occasionally spend too much time stirring and then it sets up while I'm spreading the cloth.

Errors are easy to correct. Just take the disk grinder and cut your mistakes away and start over.

So, here's a step-by-step plan for today's project:
1. Grind the surface clean.
2. Position the wooden blocks.
3. Wet the surrounding surface with acetone/resin mixture.
4. Cut the cloth pieces to fit.
5. Lay each piece of cloth, coated with mixture, before adding the next piece of cloth.
6. Work in an over-layer of mixture, smoothing any ripples.
7. Wait for it to harden.

Postscript. Karl Dick of Kenilworth took me to task in this month's Letters page and he's technically correct.

I do not claim to be any sort of expert. But I had a couple of problems that experts wanted a lot of money to correct. I taught myself some simple steps and got my job done.

I am happy when I can encourage a few farmers to take that first step on their own, and do some simple repairs. No doubt, my work will have some cracks and flaws, but it got done well enough to do the job at hand. BF

Keith Berglind is a licensed heavy-duty mechanic.