Follow the guide below to attain the desired finish when applying Scott Bader’s Crystic brush or spray gelcoats.
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Mold Prep
- Clean the mold exhaustively, ensuring it is free from any dust, debris, and contaminants.
- Apply a suitable release, again according to the manufacturer’s recommendations.
- If the mold is new, a sealing system might be needed before the release agent.
Gelcoat Prep
- Ensure the containers have no damage before opening them.
- Combine the gelcoat with a low-shear mixer and let the gelcoat stand for a minimum of 10 minutes to regain thixotropy.
- Gelcoat and workshop temperature conditions should be between 18 °C and 25 °C before use.
Catalyst/Peroxide
High-quality medium reactivity MEKP like Butanox M50 (or similar) is recommended.
Catalyst level must be maintained between 1–3 % and must remain consistent for a whole molding
Nozzle/Spray Tip Selection
Spray tip advice depends on the type of component being sprayed and the access to the mold, such as platforms, scaffolding, hose length from the spray gun, and beyond.
Always use the lowest pressure needed to achieve a uniform “finger-free” spray pattern.
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Spray Application
Spraying must be undertaken in a well-ventilated spray booth in a segregated workshop area. The mold to be sprayed must be positioned in the most ergonomic position to enable even coverage and to lessen operator fatigue.
Ensuring the wrist is flexible, begin by spraying away from the mold and bringing the gun towards it, keeping an even left-to-right spraying pattern at a constant distance of around 50–80 cm. The gun must always be perpendicular to the mold.
An arched spraying motion, as illustrated below, and tilting the gun vertically will lead to uneven coverage.
Remember: Test the gelcoat while it is still wet. The wet film thickness target must be between 500 and 600.
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Brush Application
Similar to spraying, brushing on your gelcoat requires equal care and attention for optimal results:
- Always utilize the highest quality lacquer brushes with long and soft hair
- Stir gelcoat in its original packaging prior to use
- Decant the necessary quantity of gelcoat into a clean pail
- Add 2% medium reactivity MEKP catalyst to the gelcoat and combine thoroughly to guarantee the catalyst is evenly distributed throughout the liquid
- Apply immediately using consistent, continuous strokes to attain an even wet film thickness
- Use a thickness gauge measuring instrument to verify the wet film thickness during application. The target must be between 500 and 600 μ
Remember: Always wear protective clothing, gloves, and goggles.
Image Credit: Scott Bader Company Ltd.
This information has been sourced, reviewed and adapted from materials provided by Scott Bader Company Ltd.
For more information on this source, please visit Scott Bader Company Ltd.