How Long to Wait After Spraying 2K Lacquer Before Taking a Fibreglass Mould

Cure Times, Surface Prep, and Mould Release Tips for Perfect Results

 

"After spraying my plug with 2K paint and clear lacquer, how long should I wait before applying fibreglass to ensure proper curing and avoid bonding issues when taking the mould?"

 

Great question — when spraying a plug (your master shape) with 2K paint and lacquer before making a fibreglass mould, the curing and prep time is absolutely critical to avoid issues like:

• Fibreglass sticking to the surface

• Chemical reactions (tackiness, delamination)

• Pulling up your topcoat during de-moulding

Here’s the recommended approach:

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✅ Step-by-Step: Spraying Plug Before Fibreglassing

1. Spray the Plug with 2K Base + Clear Lacquer

• Use a high-gloss 2K system — this becomes your mould surface.

• Ensure a minimum of 2–3 coats of clear lacquer for good depth and polishability.

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2. Curing Time Before Waxing or Fibreglass

• Ambient Cure (no heat):

  • Leave for at least 5–7 full days before waxing and fibreglassing.

  • This allows full off-gassing of solvents and chemical curing.

• Forced Cure (with heat):

  • If using heat (e.g. low-temp bake at 60°C for 4–6 hrs), you can reduce to 48–72 hours cure time.

  • Always allow it to cool fully and gas out after.

⚠️ If you fibreglass too early, styrene in the resin can melt or fuse into your lacquer — resulting in a stuck mould.

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3. Polish & Prepare the Plug

Once fully cured:

• Wet sand with 1000/1500/2000 grit (if needed for gloss).

• Machine polish with fine compound to mirror finish.

• Clean with a wax and grease remover (no silicone).

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4. Apply Release Agents

• Apply at least 4–6 coats of mould release wax (e.g. Meguiar’s #8, Partall, etc.) over 24 hours.

• Optional: Follow with PVA release film for extra safety (especially on first pull).

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💡 Pro Tip:

Even though the lacquer might feel dry after 24–48 hours, the chemical curing process continues internally for several more days. Don’t rush this step — you only get one shot at pulling a clean mould.

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🧪 Summary: