Do I Need to Seal the Wood Before Fibreglassing?

Why Sealing Matters

Wood, especially if old or porous, can absorb moisture and air. This can interfere with how the fibreglass resin bonds, leading to bubbling, weak adhesion, or water ingress over time. Using a suitable wood sealer, typically a low-viscosity epoxy resin, fills surface pores, stiffens fragile areas, and creates a reliable foundation for subsequent fibreglass layers.

How to Properly Seal Wood

• Preparation: Start with a dry, sanded surface that is free from dust and oils.
• Apply a penetrating epoxy: Choose a resin formulated for deep penetration, such as EpoxyWood. Use a brush or roller to coat the surface generously.
• Allow to cure: Let the epoxy set fully as per instructions. This gives a smooth, stable base for your fibreglass work.
• Light sanding: Once cured, a gentle sanding will improve mechanical bonding with subsequent fibreglass layers.

Choosing the Right Resin Products

Look for sealing resins that specify deep penetration and waterproofing, such as “EpoxyWood” for timber restoration or specialist products formulated for wood-fibreglass laminating. For high-impact projects, an epoxy like Carbon Resin delivers strong bonding and a glossy finish. For a comprehensive solution, consider a fibreglass repair kit, which includes both resin and fibreglass matting for easy application.