Fiberglass 101 - Tutorial

Fiberglass 101
Tutorial
By: TheSilentChamber

As fabricators and general car modification enthusiasts; we are often confronted with the dilemma of what materials are practical, reasonable, and best suited for the job. For many applications fiberglass falls in all of these categories. In this tutorial I am going to cover the basics, Fiberglass 101 per say, as I cover the building of a very basic but functional and attractive amp rack. This tutorial is part of a series; soon I will cover more advanced applications, different tricks and techniques, and composites other than fiberglass.

This tutorial will cover the building of a fiberglass amp rack that will fit inside a spare tire.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/01.jpg

Materials Need:

Fiberglass resin (polyester will be the most available)
MEKP (Hardener, most of the time it will come with the resin)
Fiberglass cloth
Paintbrush
Body Filler Spreader
150 grit sand paper
220 grit sand paper
Foam
Foil
Measuring cups
Acetone (Optional – needed if you want to clean and reuse measuring cups and brushes.)
Masking tape
Dremel (or other means of cutting the fiberglass)
Scissors

Step one:
We are going to start off with one of the most basic of forms, foam. This is insulating foam that can be found at any home improvement or building supply store. To get the basic shape I pressed it down on the lip of the spare, thus leaving the impression of the rim, simple but effective. Next I cut it out and sanded the edges with 180 grit and 220 grit sand paper to a smooth edge.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/02.jpg

Next we will be covering the foam in foil. If you do not cover it the resin will eat away the foam. Cover it and tape it on the back so it stays in place. If you put the shiny side up, the foil peals off of the cured fiberglass easily.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/03.jpg

After you have the foil on, the next step is to cut and lay out the fiberglass you will need. On this I will be using one layer of 18oz cloth and two layers of 4oz cloth. The weight of the fiberglass is how thick/strong the fiberglass will be. Also the heavier the fiberglass the more pattern of the weave will show up in the cured laminate and also how easily it will sand. The 18oz will provide most of the strength while the 4oz top layers will reduce bleed though of the heavier cloth on the bottom and provides a nice sanding surface. Most people will be using hardware store or auto parts store fiberglass, witch is usually around 6-8oz This builds up quick to provide strength and sands easily. If I were to build this amp rack with 8oz cloth I would want to use about 6 layers to provide the strength. I do a lot of fiberglass work so I stock various weights in bulk.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/04.jpg

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/05.jpg

Once you have the cloth cut you will need to mix your resin. Most of your typical resin will be polyester base, it provides good strength, sands easy, and is the cheapest of different kinds of resin. You want to mix at 1-2% resin to MEKP (hardener). I use 1 cup resin to ½ tsp MEKP. You can pick up some stainless steel measuring cups at most all grocery stores and supermarkets. I do not recommend using plastic as they can melt.

Once the resin has been mixed you need to cover you foil in a good layer of resin. I use cheep natural hair brushes. They run around 75 cents each so they are disposable if you don’t want to clean them.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/06.jpg

Now lay on your first layer, on this layer I used the 18oz cloth, as it will be on the bottom. Spread more resin on top of this layer working it into it by using the tip of the brush in a dabbing motion. The cloth will start to become almost clear as it is saturated. I also use a putty spreader to work the resin into the cloth.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/07.jpg

Next we will repeat the last step with the next two layers. You should place the layers on a 90* bias to each other to provide maximum strength.
http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/08.jpg
After you have gone over the resin with the spreader to it should look something like this. The spreader will squeeze out the excess resin and help achieve a good wet out.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/09.jpg

Let the resin cure. Depending on the temperature and the number of layers you put on it should take between 30 minutes and an hour. After it is cured you can remove the foam from the backside and peal off the foil. You could leave the foil on, but I always peal it off, as it will be on bottom and won’t be seen you can skip this if you want to.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/10.jpg

The surface will be relatively smooth already but you will want to sand it with 150 grit to knock down some of the high spots. I did this before I cut out the shape, it can be done before or after though.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/11.jpg

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/12.jpg

Next I used a Dremel and cut-off wheel to cut the shape. The foam left a perfect outline on the backside that I followed.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/13.jpg
Check for proper fitment and sand the edges with 150 grit.

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/14.jpg
You are now ready to paint. This could also be covered in various materials if you so wish. Primer it with a good quality high build primer

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/15.jpg

Wet sand with 220 grit with a block to level out the surface. This was smooth enough that it required no body filler, depending on what you are making and things with more complex shapes may require the use of a body filler to smooth out the surface (more on this will be covered in the next tutorial).

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/16.jpg

You are now ready to reprimer and finish out with the paint of your choice. I chose to paint it the same color as the amp, orange (yes I know the picture looks red).

http://img.photobucket.com/albums/v608/thesilentchamber/fiberglass/01.jpg

This is a very simple fiberglass laminate, but is something very easy for the beginner to start with. This tutorial will be followed by a couple more that will proceed to more complex builds and techniques. Feel free to ask any questions.

I accually wrote this for the fabrication forum, but some people here might get some use out of it also.

Great tutorial !!!

For that application wouldent a piece of 1/2" or 1/4 MDF work Alot easier for just a flat circle?

Yeah probably, but I needed something to write a tutorial on for the basics, and cant be much more basic than flat.

awesome

Would be nice if you went into how the amp "rack" was secured to the spare. (If in fact it is secured)...

Its held to the spair with hook and loop.