How to Work with Fiberglass Putty

Fiberglass strands resist surface cracking.

Fiberglass is a material found in the construction of hot tubs, boats and cars as it is lightweight and resistant to cracking, denting and breaking. The strands in the material provide its strength; depending on the item, long- or short-stand fiberglass is used; long-strand fiberglass is the stronger of the two, but it is not as easy to manipulate for repairs. Short-strand is standard for basic filling and repairs and is more pliable for easy spreading.

Things You'll Need

• Safety glasses
• Gloves
• Dust mask
• Sandpaper
• Clean cloth
• Fiberglass filler
• Hardener
• Putty knife
• Plastic sheet

Instructions

1. Sand the area to be repaired with sandpaper. Wipe the area with a damp cloth to remove all the sanding dust.

2. Apply the fiberglass filler to the plastic tray (this will be included when you purchase the filler). Add the hardener to the filler; mix the ingredients by kneading them together. The mixture is ready when it is uniform in color.

3. Apply the putty to the gap or crack you're repairing. Fill the area completely, and smooth it out to make it level with the putty knife. Allow the putty to dry completely.

4. Sand the hardened putty with fine-grit sandpaper. Depending on the coarseness of the putty, you may want to use a coarser paper first, then work down to the fine-grit paper.

Tips & Warnings

• Read and follow all safety instructions on product packaging.

References

• Crossed Flags: "Applying Fiberglass Filler": Robert Tuchrelo