Gelcoat & Fiberglass Resin Substrate

The gelcoat substrate must be cleaned thoroughly of all surface contamination prior to sanding with ALEXSEAL Surface Degreaser (A9091) using the “Two Rag Cleaning Method”.

Additional cleaning may also be performed using a professional cleaner/degreaser or a powdered cleanser (such as Ajaxor Comet®) and 3M Scotch-Britepads to scrub the surface to be painted. When rinsing the surface with clean water, the water should sheet out “break-free” – indicating a clean surface. Any breaks in the water film can indicate release agents and or other contamination present on the surface.

All resin and gelcoat substrates must be completely cured and solvent resistant.

Gelcoat substrates should be sanded with 100 - 150 grit until a surface profile of 1 mil (20 - 35 microns) is achieved. After sanding, remove dust and residual debris with clean compressed air. Wipe down the surface with ALEXSEAL Surface Degreaser (A9091).

Raw resin substrates must be ground 100% dull (no shiny spots or pits) with 36 - 60 grit.

After sanding and grinding as required, remove dust and residual debris with clean compressed air.

Important
DO NOT use solvents to wipe or clean raw resin areas after grinding and sanding. This will soften the resin and could affect the adhesion to the paint and fairing system.

Once the surface is properly prepared, you may proceed to fill and fair the surface as needed. If no filling and fairing is required, you may proceed to the application of ALEXSEAL Finish Primer 442 and/or an ALEXSEAL Topcoat. According to the needs of your application, please see the following sections:

Wood Substrate

It is important to note that when applying paint to solid or composite wood substrates, there are additional concerns of moisture and temperature that cause both physical and chemical variations in the wood. Exposed wood may expand and contract creating gaps, fissures and imperfections, requiring additional sanding and priming beyond what is done for other surfaces.

Important
ALEXSEAL Topcoat may crack when applied over joined edges or seams. When preparing wood surfaces that are planked or have a large number of seamed or joined areas, special attention should be paid to assuring that these areas are adequately filled and prepared to create a uniform, sealed surface over the wood substrate. Substrate lumber material should be fully cured and have moisture content of less than 15%. DO NOT use pressure treated wood, as the ALEXSEAL system will not adhere to this type of wood treatment.

All wooden substrates must be cleaned thoroughly of surface contamination prior to sanding with ALEXSEAL Surface Degreaser (A9091) using the “Two Rag Cleaning Method”.

All wood surfaces must be completely dry, cured out and solvent resistant. Exposed wood must be initially sanded with 80 - 100 grit sandpaper. If grinding is required to remove extensive deposits or built up material, use caution to avoid marring or deeply scratching the base wood surface.

Important
DO NOT use slow evaporating solvents to wipe or clean prepared areas after grinding or sanding. Solvents will be absorbed by the wood and could affect adhesion to the paint or fairing system. Clean virgin denatured alcohol may be used to remove oils from the wood that are exposed during the sanding process. Wooden surfaces should end up being sanded with 180 - 220 grit sandpaper to achieve a proper profile for priming. It is a good practice to vacuum and use clean compressed air to remove fine sawdust and residual particles immediately before applying any primer.

If required, seams can be filled with a polyurethane seam-sealing compound. Allow the sealer to thoroughly cure before proceeding.

Note
Polyurethane and polysulfide compounds have a certain amount of flex which will move with the wood and prevent cracking or deforming to a certain extent. Boats with dynamic seams may flex beyond the adhesion characteristics of these compounds, which can result in cracking of the ALEXSEAL topcoat. Be sure you DO NOT use any silicone-based caulk or compounds in this process.

Apply a sealer coat of high quality epoxy resin or ALEXSEAL Finish Primer 442 to seal the wood surface. This should occur within 24 hours of the sanded wood preparation, provided that the painting facility is relatively dry and maintains low humidity to prevent the exposed wood from absorbing moisture.

When sealing the wood with an epoxy resin, apply multiple coats of a high quality, clear epoxy resin per the manufacturer’s recommendations. Always wash down the cured epoxy resin surface with water before sanding and applying additional products.

When sealing the wood with ALEXSEAL Finish Primer 442, refer to instructions in the “Technical Data Sheets” starting on page xx. The first coat of primer should be reduced 30 - 40% to allow for the sealer coat to soak into the grain. After the sealer coat has been allowed to dry overnight – but not more than 24 hours – at 25° C (77° F) apply two to three additional coats of Finish Primer 442 mixed and reduced as described in the Technical Data Sheet. If more than 24 hours passes before applying additional coats of primer, the surface must be sanded with 180 - 220 grit sandpaper.

Always use ALEXSEAL Wipe Down Solvent (A9049) AFTER the primer has been applied. Use ALEXSEAL Surface Degreaser (A9091) or virgin denatured alcohol to remove oils from the wood after sanding and prior to the application of primer.

Once the surface is properly prepared, you may proceed to fill and fair the surface as needed. If no filling or fairing is required, you may proceed to the application of ALEXSEAL Finish Primer 442 and ALEXSEAL Topcoat. According to the needs of your application, please see the following sections:

Plastic Substrates

There are several types of plastic used in the marine industry.  Some of these plastic products include Sintra Board, PVC, Plexi Glass, Lexan, and Starboard.

Sintra Board
Sintra Board is a PVC material supplied in sheets of various thicknesses. It can be cut and shaped like ply wood and is very popular to use as overhead panels on a yachts because it will not rot, is light weight, can be painted, and is easy to use. It does have a fine textured finish and is somewhat greasy to touch.

To paint Sintra Board with ALEXSEAL 501 topcoat the following is recommended:

  1. Clean with ALEXSEAL A9091 Wax and Grease Remover using the two rag method.
  2. Sand the surface and edge to painted with 120 – 240 grit dry sand paper.
  3. The surface should be cleaned using clean dry compressed air and clean rags to remove all dust.
  4. Apply 2 coats ALEXSEAL Finish Primer 442 or 1 cross coat ALEXSEAL Fast spot Primer 414 per TDS recommendations.
  5. Sand smooth with 280 – 320 dry sand paper.
  6. Apply 2 – 3 coats ALEXSEAL Topcoat 501.

Information about Sintra Board panels can be found at www.sintrapvc.com

PVC
PVC like type used for PVC pipe can be painted with ALEXSEAL Topcoat 501 directly after solvent wipe and scratch sanding with 320 grit dry sand paper. You can also prep, prime and paint per the same recommendation as the Sintra Board.

Plexiglas and Lexan
Plexiglas and Lexan can be cleaned, sanded, cleaned and cleared or painted with ALEXSEAL Topcoat 501.

Starboard
Starboard has a very greasy feel as it contains an oily type of silicone and cannot be primed or painted. “Starboard” with primer and or paint, sanded or un-sanded will delaminate.

Information about Starboard can be found at https://www.kingplastic.com/products/king-starboard/

Aluminum Substrate

Degrease the aluminum substrate with ALEXSEAL Surface Degreaser A9091 using the „Two Rag Cleaning Method“.

To achieve optimum adhesion and performance, the aluminum should be ground with 36-60 grit or sand / grit blasted to a 2-4 mil (50-100 micron) profile and a very clean, silver / white appearance.

Important
DO NOT wipe the surface with rags after blasting or grinding. The aluminum surface will snag fibers that will act as wicks through the protective primer and could decrease corrosion resistance.

Abraded aluminum surfaces should be cleaned using clean, dry compressed air and a bristle or nylon broom to remove all dust before product application.

Application of ALEXSEAL Protective Primers should occur as soon as possible (within 12 hours) after the abraded or blasted metal preparation, provided the painting facility is located away from coastal saltwater regions and the aluminum substrate is kept indoors, dry and clean. Aluminum will begin to oxidize immediately after sanding or blasting, and this process will be more rapid in coastal locations. For the best adhesion, surfaces should be primed as quickly as possible after preparation.

During the system application, after the application of the ALEXSEAL Protective Primers, all surfaces should be cleaned using clean, dry compressed air and clean rags to remove all dust before product applications throughout the system. Apply ALEXSEAL Protective Primers in accordance with their respective „Technical Data Sheets“.

Once the surface is primed with Protective Primer 161, you may proceed to fill and fair the surface as needed. If no filling and fairing is required, you may proceed to the application of ALEXSEAL Finish Primer 442 and / or an ALEXSEAL Topcoat.

According to the needs of your application, please see the following sections:

Steel Substrate

Degrease the steel substrate with ALEXSEAL Surface Degreaser A9091 using the „Two Rag Cleaning Method“.

To achieve optimum adhesion and performance, steel should be prepared by sanding / grit blasting to near-white metal Sa 2.5 (SSPC-SP10-85) and / or ground with 36 – 60 grit to a 2 -4 mil (50-100 micron) profile.

Important
DO NOT wipe the surface with rags after blasting or grinding. The steel surface will snag fibers that will act as wicks through the protective primer and could decrease corrosion resistance.

Steel surfaces should be cleaned using clean, dry compressed air and a bristle or nylon broom to remove all dust before product application.

After the application of an ALEXSEAL Protective Primer, but before each subsequent product application, all surfaces should be cleaned using clean, dry compressed air and clean rags to remove all dust and contaminants.

Application of ALEXSEAL Protective Primers should occur as soon as possible (within 12 hours) after the abraded or blasted metal preparation, provided the painting facility is located away from coastal saltwater regions and the steel substrate is kept indoors, dry and clean. Apply ALEXSEAL Protective Primers in accordance with their respective „Technical Data Sheets“.

Once the surface is primed with Protective Primer 161, you may proceed to fill and fair the surface as needed. If no filling and fairing is required, you may proceed to the application of ALEXSEAL Finish Primer 442 and / or an ALEXSEAL Topcoat.

According to the needs of your application, please see the following sections:

Protective Primers

ALEXSEAL Protective Primers
ALEXSEAL Protective Primers have unique chemical inhibitors and bonding agents that have been formulated to be applied over substrate materials. The ALEXSEAL line of Protective Primers is comprised of the following products:

ALEXSEAL Protective Primer 161 is an epoxy based primer used for interior and exterior applications. Due to specific corrosion inhibitors and a combination of epoxy resin binding agents, this primer offers excellent adhesion promotion on all substrates as well as corrosion protection on steel and aluminum substrates. ALEXSEAL Protective Primer 161 can be used for corrosion protection and adhesion promotion on steel and aluminum substrates, both above and below the waterline. This product is unique in that a surface primed with 161 can stand for up to 6 months and still be overcoated without the need for sanding.

ALEXSEAL Cor Spec Primer 135 (US only) is a chromate-containing, two component epoxy primer for use on metal substrates. This product is highly resistant to corrosion and chemicals. ALEXSEAL Cor Spec Primer 135 is designed to prime and seal old and new, properly prepared, metal surfaces prior to the application of ALEXSEAL Topcoats or ALEXSEAL Finish Primer 442. This product is ideal for masts, parts and metal substrates. It may be directly finished with topcoat or primed, depending on the application requirements. Cor Spec Primer 135 may be used above and below the waterline.

Once the surface is primed you may proceed to fill and fair the surface as needed. If no filling and fairing is required, you may proceed to the application of ALEXSEAL Finish Primer 442 and / or an ALEXSEAL Topcoat. According to the needs of your application, please see the following sections:

Final Preparation for All Substrates: Two Rag Cleaning Method

Important
Before moving on to the application of fairing compound, surfacing products or topcoats, it is important to follow these steps to make certain the surface is free of particles of and contaminants of all sizes. Failing to follow this process could result in subsequent coatings not bonding properly, and defects that may become apparent after the finish coats are applied.

Step 1: Use a shop vacuum or clena, dry compressed air source to remove dust and particulates from the surface while wiping with a clean, oil free, and dry cotton cloth.

Step 2: Wet one cloth with ALEXSEAL Surface Degreaser A9091 or ALEXSEAL Wipe Down Solvent A9049. Use this cloth to wet the surface and loosen contaminates. For information on choosing between the Surface Degreaser and Wipe Down Solvent products, please see „Surface Preparation“.

Step 3: Use the dry, second cloth to wipe the surface and lift away or remove contaminates. Work small areas – approximately 1.2 m² (4 sp.ft.) or less – to keep the solvent from evaporating before using the second rag to wipe clean. DO NOT allow the solvent to dry on the surface prior to wiping it off.

Repeat steps 2 and 3 – always keeping the rags clean – until the surface is clear of any contaminates.

Important
Using only one, wet cloth only serves to thin and dissolve contaminates before simply spreading them around. Be sure the cloths used in procedure do not have any contaminates.

DO NOT use pretreated shop towels! Industrial paper towels are good choices to use for wiping down the surface, provided they do not have any chemical or pre-treated additives. When solvent wiping for ALEXSEAL Finish Primer 442, verify the entire surface is completely dry before using tack rags.

Tip
Use the „Application Record“ to document your application process, equipment settings and environmental conditions for future reference.