If you've bought a fiberglass kit, you'll need to know how it works, otherwise you'll make a mess. The first step is to build your mold, then you can move on to preparing the fiberglass and working with the glue. Working with fiberglass is not too complicated, indeed it is quite simple. The details in this guide will complement your kit's instructions, ensuring you get a good result.
Steps
Part 1 of 3: Prepare and Build the Mold
Step 1. Buy a fiberglass kit
A kit should contain the polyester resin, catalyst and fabric to give it structural rigidity. Kits can be bought at DIY or auto parts stores, and are sold in different sizes depending on the projects to be performed.
What exactly is fiberglass? In the beginning it is a liquid. This liquid is then extruded through small holes, which transform it into small filaments. These are coated with a chemical solution and joined to create a rope, or skeins of fiber. By adding resin, a strong, durable and flexible glass fiber is obtained
Step 2. Think about which mold to use
If you are making a fiberglass project, such as a box, cup or other object, you will need a mold to make the fiber, initially liquid, harden into the correct shape. If, on the other hand, you need to make a repair on a boat or a car, consider the possibility of delimiting the area to be repaired with the tape and applying the resin directly to the point in question.
Step 3. Use foam or flexible material for molds of fluid shapes
Foam or polystyrene blocks are best for curved or irregularly shaped objects. Cut or dig the foam into the desired shape, such as a fountain tub, bird tub, or dome. Cover the material with wax paper and use wax to seal, join the seams and smooth out any inaccuracies.
Step 4. Use cardboard, plywood, MDF or other rigid materials for the molds of linear or geometric shapes
Rigid materials are best for larger projects, such as a dog house or even a boat. To make these molds, cover the entire surface with wax paper, or a well-established coat of paraffin wax. You can also use a vegetable wax.
Step 5. Prepare the woven fiberglass sheets, cut them to the correct size for your mold, taking into account that you need to overlap the sheets in corners or tight curves
The material will become very flexible when you apply the resin, so don't worry if you can't position the sheets properly when dry.
Part 2 of 3: Mix and Apply the Fiberglass
Step 1. Measure the exact amount of resin in a vessel
You can use a large can or a metal cup, but it would be better to use a disposable container. You can also mix the resin in a clean plastic container, but as it generates heat when it dries you need to be very careful.
Step 2. Add the catalyst following the instructions on the package
In each kit there is a measuring cup or tubes with premeasured components.
Step 3. Mix the two components with a stick
Mix well, at the bottom and sides, not just in the center.
Step 4. Once the fiber is in place, smear the resin with a disposable brush
The fiber will appear to melt into the resin as you lay it out, and you can lay more layers down to half a centimeter thick.
Make sure you spread the resin well even in the corners and weak spots. If you don't cover the corners well, the result may be weak
Step 5. Continue brushing until the mold is evenly covered
Continue until you run out of material available.
Part 3 of 3: The Finishing
Step 1. Clean tools and remove drops with acetone based solvent before material hardens
Acetone is perfect for cleaning fiberglass because it is strong and evaporates quickly. Make sure you don't get parts of the mold wet with acetone. Keep it away from plaster, plastic, and rubber as well.
Step 2. Repeat the fiberglass and resin application until the project reaches the desired thickness
The fiberglass is usually applied in sheets until it reaches an adequate thickness to give the required strength. Depending on your project (you can always vary the quantities) try to use at least three layers, and no more than ten.
- If possible, try to position the fiberglass sheets by orienting them in different directions on top of each other - the fiber is stronger when crossed. Especially in the weak points, if the fiber is crossed in layers, the result will be better.
- Smooth out imperfections between layers so that the fiber does not protrude from the resin layer.
Step 3. Finish the project with a coat of resin
Then apply a coat of polyurethane or enamel if you wish.
Step 4. Remove the fiberglass from the mold
If you put a layer of wax paper on it should peel off well. The fiber does not stick to the wax.
Advice
- Soften the corners if you can, as it is difficult to work the fiber in tight corners.
- Temperature affects the hardening rate of the polyester-based resin, as does the amount of catalyst used.
- If you have the right equipment, you can also apply multiple layers of fiber at once.
- To make sure the fiber is evenly soaked in resin, squeeze the fiber between two sheets of plastic. Use a plastic scraper or an old credit card to smear the resin onto the fiber sheet. You can also adjust the mixture into the desired shape with the help of the plastic. This will make it much easier to clean everything up once it's done.
- For larger projects you can make separate sections, then use the same fiberglass to join them together.
Warnings
- Work in a well-ventilated area.
- Polyester-based resin produces noticeable heat when it dries, especially if the catalyst component has been used in abundance.
- Wear protective gloves and goggles when applying resin and avoid contact with eyes.
