A Guide on How to Process Fiberglass

Fiberglass is often found in boat hulls.

Fiberglass is a versatile material that can be used in many automotive, residential and art projects. What most people think of as "fiberglass" is actually made up of two parts: the fiberglass material (commonly available in cloth and mat forms) and the chemical resin that bonds layers of fiberglass together into one solid piece. If you have never processed fiberglass before, practice on a piece of plastic or cardboard before moving on to projects involving your car or home.

Things You'll Need

• Cardboard
• Petroleum jelly
• Paper towels
• Fiberglass cloth and mat
• Fiberglass resin and catalyst
• Disposable buckets
• Paintbrushes
• Protective gloves, goggles and clothing
• Dust mask
• Electric sander or sandpaper
• Rotary tool with cutting blade
• Scissors (optional)

Instructions

1. Lay the plastic or cardboard sheet on the floor in a well-ventilated area.

2. Brush a thin layer of petroleum jelly onto the sheet to act as a release agent. Wipe away any excess with a paper towel. You don't need much, just a micro-thin layer to prevent the resin from bonding with the sheet.

3. Put on protective gloves, goggles and clothing. The glass fibers and dust that will be created are skin irritants. Be sure to protect yourself.

4. Cut or tear the fiberglass cloth or mat into squares. The size of the squares will vary depending on the project you are working on, but five or six inches is a good size for practice purposes.

5. Mix a batch of fiberglass resin with its catalyst according to the instructions on the resin container. Use a disposable bucket, as dried resin is hard to remove from a container that you want to use again.

6. Brush a layer of catalyzed resin onto the released area of the sheet.

7. Lay squares of fiberglass into the resin on the sheet, overlapping them by a quarter-inch to ensure that no spots are missed.

8. Tap more resin into the fiberglass with the brush, saturating the fibers completely. Tapping will help force out any air bubbles that may become trapped; these bubbles weaken the finished product. Make sure you have all bubbles removed.

9. Add a second and third layer of fiberglass squares onto the sheet, each layer saturated with resin. Continue to tap out any air bubbles between layers.

10. Allow the fiberglass to cure fully. This will take several hours. You will know it is complete when the fiberglass has hardened and is no longer tacky.

11. Remove the fiberglass sheet from the plastic or cardboard.

12. Put on a dust mask to protect your lungs from any fiberglass dust you are about to create.

13. Trim the rough edges of the fiberglass sheet with a rotary tool.

14. Sand the fiberglass sheet smooth with an electric sander. Begin with a coarse sandpaper, then move to a finer grit.

Tips & Warnings

• Fiberglass cloth is made of woven glass fibers, which must be cut with scissors. It provides greater strength but can be harder to work with.

• Fiberglass mat is a mesh of chopped pieces of glass fiber. It can be torn and is much easier to work with, but it is not as strong as cloth.

• Once you have learned how to create a flat sheet of fiberglass, try working on a box, ball or another three-dimensional form to get the hang of curves and corners.

• Resin fumes are major lung irritants. Work with proper ventilation.

References

• Serious Explorations: Step by Step Fiberglass
• AJ Quick: Fiberglass Tutorial