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Gelcoat application · 7 steps

In a mold

Gelcoat goes on first and becomes the outside face after demolding. Do not add finishing wax to the face that will receive the laminate.

White gelcoat being sprayed onto the inside of a blue mold.

  1. Step 1. Prepare the mold

    Clean the mold and apply the specified release system. The finish will reproduce the mold surface.

    Clean and inspect the mold

    Apply the release system

    Release agent goes on the mold so the part can separate. It is not finishing wax and does not belong on a repair bonding surface.

  2. Step 2. Prepare unwaxed gelcoat

    Use gelcoat without finishing wax, suitable for the application method and the laminate that will go behind it.

    Gelcoat first, on the prepared mold

    Use suitable unwaxed gelcoat where laminate will bond. The release layer is below the gelcoat, against the mold; layer thicknesses are schematic.

  3. Step 3. Mix and catalyze

    Homogenize the material. If tinting, use approved pigment within its limits, blend before MEKP and validate a separate cured sample. Catalyze only an amount you can apply within its working time, following the specified ratio and measurement basis.

    Tinting your gelcoat? See how to color polyester gelcoat

    MEKP last, when ready to apply

    Mix and use within working time

    Use the actual gelcoat instructions for catalyst type, amount, measurement basis and conditions. The illustrated color is not a pigment recipe.

  4. Step 4. Apply and measure

    Apply a uniform film using the permitted method and verify the specified wet-film thickness. Check corners, thin areas and buildup.

    Apply evenly

    Verify the specified thickness

    Use the permitted application method and measure the specified wet-film thickness. Observe coat intervals; this diagram is not to scale.

  5. Step 5. Wait before laminating

    Wait for the specified backing condition before placing resin and fiber. Do not rely on the clock alone.

    Check readiness for the backing laminate

    This is the stage for adding the backing laminate, not a generic instruction to wait for full cure. Check the specified condition and window, not just the clock.

  6. Step 6. Apply the fiberglass backing

    Add the first fiber layer with laminating resin and remove air. Continue with the layers specified for the part.

    See how to place the first layer without repeating the gelcoat

    Place the reinforcement

    Wet out and make contact

    Use the reinforcement and sequence specified for the job. Wet out without dry areas or bridging; the backing shown is generic.

  7. Step 7. Allow to cure and reveal the finish

    Complete the laminate and allow it to cure before demolding. Once the part is separated, the gelcoat is on the visible face.

    Meet the demolding requirements

    Separate and inspect the part

    Demold only after the required cure. Inspect the part and finish its edges; elapsed time alone does not certify readiness.