Working with fiberglass or FRP materials isn’t hard — but even experienced fabricators can slip up. A small mistake in mixing or curing can ruin a whole batch, costing time and money. Here are five common FRP mistakes (and how to dodge them).

1. Wrong Resin Ratio

Too much catalyst and your resin overheats or cracks. Too little and it never cures right. Always measure accurately — not by eye. Most resins need 1–2% catalyst (like MEKPO), but check your product data sheet first.

2. Poor Surface Prep

If your mold isn’t clean or waxed properly, your part won’t release smoothly. Dust, oil, or leftover gelcoat can cause bubbles and dull patches. Take time to clean, seal, and prep the surface before you start.

3. Skipping Air Release

Trapped air weakens your lamination and ruins the finish. Use an air-release agent or a roller between layers to push out bubbles. It’s a small step that makes a big difference.

4. Ignoring Temperature & Humidity

FRP hates extreme conditions. Too cold — it won’t cure. Too hot — it cures too fast. Keep your workspace around 25°C with balanced humidity for the best results.

5. Using the Wrong Reinforcement

Not all mats or rovings work for every job. Need flexibility? Go with chopped strand mat. Need strength? Woven roving or fabric is better. Match your reinforcement to the part’s purpose.

💡 Pro Tip:
Always keep your technical data sheets (TDS) nearby — they’re your recipe for success.