Surfacing is the process of refining a surface that has been faired or is not in need of a full fairing system. Surfacing corrects minor imperfections in a surface and creates a more precise layer above a full fairing system. ALEXSEAL Super Build 302 and Fine Filler 303 are superior products for surfaces that are faired, or do not require a full or thick fairing system application.

After imperfections such as ridges and holes are filled and corrected with fairing materials, a final surfacing process should be utilized to feather the material out. This creates a uniform surface that is consistent with the substrate. Surfacing takes a surface that is 95% faired, and smooths out the last remaining imperfections. Surfacing is the final filling step, which creates a uniform base that accepts a finish primer that seals the surface. This process increases the overall strength and integrity of the final coating while adding an intermediate protective barrier.

    ALEXSEAL Fine Filler 303

    ALEXSEAL Fine Filler 303 is a solvent-free, epoxy-based filler which cures without shrinking. It cures as a water resistant solid coating. This is an ideal product to use between ALEXSEAL Fairing Compound and ALEXSEAL Super Build 302 or ALEXSEAL Finish Primer 442. Fine Filler 303 is used when a tight pull of fairing is required to fill small imperfections prior to applying a surfacer or finish primer. ALEXSEAL Fine Filler 303 is used to fill and fair minor surface imperfections.

    Important
    It is critical that no polyester filler is applied directly below or directly on top of ALEXSEAL Fine Filler 303. Polyester fillers are not designed for heavy filling or fairing. It is also important that Fine Filler 303 is not applied over caulk or any other soft product.

    The substrate must be clean, dry and free from dust, grease, oil and other contamination. The substrate should be properly prepared as described in “Substrate Preparation & Priming” starting on page xx. Optimum mechanical resistance values are achieved by proper surface preparation.

    ALEXSEAL Fine Filler 303 may be applied as a high film surfacer over ALEXSEAL primers and fillers, or gelcoat and raw resin lay-up. The surface must be sanded with 80 - 150 grit. Fiberglass resin should be ground with 36 - 60 grit and/or sand blasted. The surface and the bottom of any fiberglass profile should be dull and abraded with no shiny spots.

    ALEXSEAL Fine Filler 303 is easily applied by spatula, trowel or other straight edge with careful attention to avoiding the introduction of air pockets. Applying the product to the surface in thin layers of 2 mm and working up to the desired thickness before pulling the product out with a straight edge, will help avoid creating air pockets in the applied product.

    ALEXSEAL Fine Filler 303 should be sealed with ALEXSEAL Super Build 302 and ALEXSEAL Finish Primer 442 prior to applying topcoat.

    The components of ALEXSEAL Fine Filler 303 have different colors to control the mixing process. After mixing, the color of the fillers should be a homogeneous color. If the base and converter are not mixed thoroughly, it could result in an improperly cured batch. Mixing can be done mechanically with slow turning dough mixers or manually.

    Important
    DO NOT use drill mixers. The introduction of air bubbles should be avoided.

    For equipment cleaning, use ALEXSEAL Epoxy Primer Reducer (R4042). ALEXSEAL Fine Filler 303 should be block sanded with 100 - 150 grit. Block sanding with 150 grit or finer will help prevent sand scratch print-through in the finished system.

    For details concerning the application of the product please refer to the technical data sheet of the product.

    After the surface is faired to the desired quality using ALEXSEAL Fine Filler 303, apply Super Build 302 or Finish Primer 442 to achieve a surface that is sealed, and ready for topcoat. Continue reading this section for instruction on using Super Build 302, or refer to “Final Priming & Sealing” for instruction on using Finish Primer 442.

      ALEXSEAL 302 Super Build System

      ALEXSEAL Super Build 302 is an epoxy-based high build primer/surfacer which cures into a smooth, easy to sand, water resistant coating. ALEXSEAL Super Build 302 has excellent spray characteristics and is fast drying to allow maximum efficiency while fairing. The cured film offers excellent mechanical resistance values. ALEXSEAL Super Build 302 is used to seal ALEXSEAL Fairing Compound and to even out imperfections remaining after the filling and sanding process. It also is designed to be used as a smooth, non-porous surfacer prior to the application of ALEXSEAL Finish Primer 442.

      ALEXSEAL Super Build 302 may be applied over sanded fillers such as ALEXSEAL Fairing Compound 202/212/242, Spray Fair 328 or Fine Filler 303. After sanding the ALEXSEAL Fairing Compounds with 60 - 150 grit, the surface must be cleaned and dusted off thoroughly before applying ALEXSEAL Super Build 302. ALEXSEAL Super Build 302 may be applied as a high build surfacer directly over gelcoat and raw resin lay-up. Gelcoat must be sanded with 80 - 150 grit.

      The substrate must be clean, dry and free from dust, grease, oil and other contamination.

      Note
      Old coatings must have good adhesion and chemical resistance, and must be sanded with 100 - 150 grit. If the old coating is of questionable quality, a compatibility test should be performed, as described in “Project Considerations” .

      ALEXSEAL Super Build 302 should be sealed with ALEXSEAL Finish Primer 442 prior to top coating.

      For details concerning the application of the product please refer to the technical data sheet of the product.

      After the surface is faired to the desired quality using ALEXSEAL Super Build 302, apply ALEXSEAL Finish Primer 442 to achieve a surface that is sealed, and ready for topcoat. Proceed to “Final Priming & Sealing” starting on page xx for instruction on using Finish Primer 442.

      Once a substrate has been faired and surfaced as necessary to achieve the expected quality of finish, the surface is ready for final finish priming and sealing. The surface should be abraded to a proper profile that is free of debris and contaminants before proceeding.

        ALEXSEAL Finish Primer 442

        ALEXSEAL Finish Primer 442 is an epoxy-based finish primer offering advanced adhesion qualities over various substrates, exceptional sanding characteristics, and good film build up. Finish Primer 442 is designed to prime and seal old and new, properly prepared, stable surfaces such as gelcoat and fiberglass, as well as to seal other ALEXSEAL primers and filler systems. Using this primer as a base greatly enhances the “Wet Look” of an ALEXSEAL Topcoat. Finish Primer 442 may be used above and below the waterline.

        Important
        The following are notes for sealing ALEXSEAL Fairing Compound, Fine Filler 303, Spray Fair 328 and Super Build 302 with Finishing Primer 442:

        The substrate must be clean, dry and free from dust, grease, oil and other contamination.

        • Fiberglass and gelcoat can be coated directly with ALEXSEAL Finish Primer 442 after sanding with 100 - 150 grit.
        • Old coatings must have good adhesion and chemical resistance and must be sanded with 100 -150 grit. If the old coating is of questionable quality, a compatibility test should be performed, as described in “Project Considerations”.