Bottom Painting Never Got E

There really are a number of antifouling paint products on the market and choosing one can get confusing. There are a lot of people selling paint products who really aren’t up on product data themselves, so it makes it increasingly difficult to select the right paint for your particular application beyond the color you wish the fish to see.

            The first thing you need to know is there are single season paints and multi season paints. This is particularly important for boaters who remove their boats in the fall for winter storage. When using a single-season paint, they become minimally effective when the paint dries.  Therefore to get the best protection you really have to paint each and every spring.  Those who trailer their boats from lake to lake should be concerned with this adverse drying affect as well, because when it dries, it simply is not as effective as it is when a boat is left in the water.

             Another characteristic of the classic single-season paint is that the toxicant leaches away from the paint itself. The paint stays on the hull longer than the toxicant does. So, it is common for boat owners to look at their hulls full of paint (albeit an old application) and assume there is toxicant left in the paint. Not true.  The toxicant could be gone. However, if the paint application is relatively fresh and the toxicant hasn’t leached out, but only suffers from the chemical change, then you can burnish the surface to open up the toxicant for better performance.

            These single season paints are also hard and not self polishing (ablative) and hence build up in time to the point where you must remove it periodically to prevent unnecessary build up after it cracks and starts to flake off. When kept wet, you could expect 12-18 month performance with the recommended application of two coats.

            The alternative is multi-season paints and when it comes to Interlux, the largest paint manufacturer in the world, it starts with Micron Technology, which they claim are second to none.  So, read on, but expect even a newer technology for much quicker applications,  recently introduced which may really be appealing to you (later in this article).

            Micron is not new. It was first introduced back in the 80’s, but has evolved to an extremely effective coating in that it is longer lasting (18 to 36 months depending on paint type, usage and number of coats applied). Micron produces a smoother finish and uses less copper for longer protection. The paint and the toxicant leach away at the same time eliminating build up and you can haul and re-launch without repainting (multi-season).  

            Consider this.  Old paint technology provided products that had more cuprous oxide toxicant in the paint designed for the worst fouling conditions. Not only were they more expensive because toxicants added to the price of the paint, but, because of their hard application, the toxicants were trapped in the deeper layers of the paint where they remained ineffective unless you sanded deeper to get to get at them, which increased your labor equation. With Micron technology, lesser amounts of biocide is needed, yet it gives you longer antifouling protection as the paint leaches away, at a controlled rate, over the life of the paint, which is essentially when the paint is gone. So, if one were to draw a graph you would easily see the difference between old antifouling and Micron where the Micron release of antifouling is longer than that of the original hard surfaces.

            Other advantages of the Micron technology are that you can easily touch up needed areas, and when a reapplication is necessary, there is no need for laborious prep work. You can paint without sanding. And it is effective in all fouling conditions, for both sailboats and powerboats (up to 50 knots).

            It is recommended that you always read the label and product information before you use any paint and know the application preparation procedures on the substrate you are working with, but here is a basic rundown and quick reference to Interlux Antifouling paints.

            There are several types of Micron Technology paints. Let me explain the differences:

            MICRON 66 – (not suitable for use in fresh water) – Is the top of the Micron range with the best antifouling performance in the harshest antifouling conditions. It works well even if the boat sits at the dock for long periods of time (2 years and beyond). Can be hauled and relaunched without recoating. When applied over TBT co-polymers, wet sand with 80 grit paper, clean with 216 thinner and prime wth Primocon or TBT sealer. Over non-TBT co-polymers and other hard antifoulings, wet sand with 80 grit and clean with 216 thinner. Apply at least 2 coats with brush or roller and extra on high wear areas (leading edges, rudders, etc.). Colors: Blue, Green, Red, Black.

            MICRON EXTRA – Uses Bilolux technology to reduce slime. Good for all boats in all waters. Can be relaunched without coating and can be applied over existing paints. Remove loose paint by sanding with 80 grit (dry) and wipe down with 216 thinner. If you have a good strong application of any Micron technology paints on your hull, no sanding is required for a recoat. Simply powerwash the paint, scrub with a brush, let dry and reapply at least two coats with brush, roller, airless or conventional spray and extra in high wear areas. Colors: Blue, Green, Red, Black, Shark White (gray), Brown and Dark Blue.

            MICRON CSC – Proven performance over 20 years. It is harder than other copper co-polymers so polishes at a slower rate. No build up. Longevity related to the number of coats applied. Haul & relaunch without recoating.  Wears down like a bar of soap. Suitable for power and sail, it can be applied with brush, roller, airless or conventional (pressure pot) spray over previously painted surfaces. Prep the same as Micron Extra. Colors: Red, Black, Blue, Green and Shark White.

            In Micron Technology, you have two best basic choices (which keeps it simple) and that is the Micron Extra and CSC. The difference really is that the Extra has Biolux, which is an organic boosting agent which eliminates the brown and green algae slime that resides on most hulls with antifouling paints that do not have Biolux properties. Zebra mussels and barnacles feed on these algaes and hence attach to your hull. By eliminating most of this algae, these crustaceans do not attach to the hull and when they do, the biocide prevents the attachment.  Micron CSC does not have this Biloux boosting agent. It is cheaper than Extra, but if you are in an area where you have zebra mussels or barnacles, you are better off with CSC.

            MICRON EXTRA VOC – This is a multi-season co-polymer with cuprous oxide which controls shell fouling and Biolux technology which helps prevent weed, slime and algae growth. It wears away with use eliminating build-up of old spent coatings. The number of coats applied relates to the longevity of the paint application (brush, roller, airless or conventional spray – pressure pot). Micron Extra VOC meets the most stringent VOC regulations including California. It has exceptional antifouling performance in all conditions, is self polishing (no build up) and can be used on Fiberglass, wood and primed underwater metals (except aluminum). Preparation is the same as Micron Extra.  Colors: Blue, Green, Red, Black and Shark White.  It is not found everywhere, but rather is more popular in states like California.

            All of the above paints can be applied on fiberglass or wood substrates and properly primed underwater metals such as lead and steel (but not aluminum).  With wood, the first coat should be thinned. With application by brush, the average coverage is about 440 ft2/gallon, with Micron Extra VOC pushing to nearly 500 ft2/gallon.

            There’s one more ablative antifouling from Interlux that is a very economical to use and is a season to season paint, but is not part of the Micron Technology and it is called FIBERGLASS BOTTOMKOTE ACT with Irgarol.  This paint is inexpensive and has wearing away tendencies, but the difference is it is not at a controlled rate like the Micron paints. The wearing away is dictated by the action of the water, so, in certain conditions the paint can wear away faster. Micron paints have more bonding characteristics with stronger resins. ACT lacks this and hence will break down quicker and so it is recommended and you will find that you need to reapply coats more frequently.

            Are you into easy?  Read on:   

            FIBERLASS BOTTOMKOTE /NT – is the breakthrough dual resin technology that speeds up your bottom work.  This product has replaced the original Fiberglass Bottomkote and is a single-season paint, but doesn’t build up as fast as Bottomkote did. This product provides a universal durable, fast dry coating that delivers the benefit of both hard and ablative antifouling for all power and sailboats. This means it is similar to the hardness of the traditional paint, but also has a slow polishing mechanism that smoothes and renews the surface avoiding heavy build up like an ablative paint.  It is less expensive than Micron CSC, but only has 28% copper versus the more customary 43% found in Micron paints. It is low copper, low cost and fast drying. You can paint and launch the boat in the same day. It is designed for fiberglass, wood and primed metal (except aluminum) hulls. It is good for salt, brackish and fresh water. Very cost effective and it can be applied over previously painted surfaces after sanding with 80 grit paper and cleaning with 216 thinner. Apply two coats (first coat thinned 10% on wood). At 75 degrees you can paint every 2 hours and launch in 6 hours. At 95 you can recoat every hour and launch in 3 hours. At 50 degrees this drops to a 6 hour recoat and 12 hour launch. Colors: Black, Blue, Green & Red.

            Don’t like sanding?  Read on about Interlux’ Simple No Sand System for bare, previously unpainted fiberglass hulls. There are basically three no sand systems. They all use the Fiberglass Surface Prep product.

            Removal of surface contamination is extremely important to prevent follow up paint failure. FIBERGLASS SURFACE PREP emulsifies and lifts mold release agents used in fiberglass boat manufacturing. It is applied with a 3M Maroon Scotch-Brite pad. On large surfaces you can apply it with a roller from a paint tray, but do one section at a time. Scrub with medium pressure and then flush the surface with fresh water or wipe with a clean, wet cloth, changing cloths frequently until all contamination is used. Run water over the surface. If water beads up or separates, clean again with Fiberglass Surface Prep. Rinse again and dry (air or cloth).

The first no sand system is called the Simple No Sand System and it incorporates the application of the above surface prep followed by the application of FIBERGLASS BOTTOMKOTE AQUA. No sanding, no priming. Aqua is a water-based for all types of fouling including zebra mussels. It has reduced emissions, low odor, is colorfast, can be cleaned up with water and has a color selection of red, blue and black. 

            The Ultimate No Sand System uses the surface prep as described above with the application of InterProtect 2000E epoxy primer (just one coat).  This gives you a tie coat and you can apply the antifouling of your choice within the window allotted based on the temperature you are working in.

            The third No Sand System uses the surface prep as described above and then the application of one of the Interlux No Sand Primers.  Within 4 hours you can apply one coat of Interlux’s No Sand Primers by brush, roller, but do not spray. Do not use Fiberglass No Sand Primers with Micron 66, VC17m or Extra, Fiberglass Bottomkote Aqua, Micron Optima, VC Offshore, Baltoplate or any other water based or vinyl antifouling paints. These primers are urethane based and so in very hot and humid conditions, the application window for the follow up antifouling paint reduces drastically. So, check product information.

            There are other Interlux products that might interest you and your particular application.  TRILUX 33, available in cans or aerosol, is a derivative of copper safe for aluminum and comes in brighter colors.

            If you want copper free antifouling, then PACIFICA PLUS is an ablative paint that has multi season qualities, but is not really boasted as a multi season paint. It is expensive and contains a biocide called Econea which controls shell fouling well. It is available in red, black and blue.

            Interlux also has the VC Systems products which include VC 17m, VC Extra and VC OFFSHORE.  VC Offshore is a vinyl-based, high-load copper which is burnished for a super-smooth racing finish. Good for fresh or salt water.  If money is no object, then it is a better alternative to the other VC 17 paints, but they are not compatible.  While VC17 and VC extra can be applied with little preparation, the VC Offshore must have a preparations of sanding and a coat of Interprotect 2000 and another sanding after it has completely sealed.  There is no chemical attachment of these products, so labor is more, but results are excellent.  Also, there is no color change after the hull gets wet. What you see out of the can is what you will see over the life of the paint.

            VC 17 products have a fluoro micro additive for reduced friction and are excellent for racing boats in fresh water.  They are single season paints, but yearly application requires no sanding. Just clean with water, dry, mask and roll on. It can also be buffed to get a super smooth racing bottom.

            I can’t finish without stressing safety with the use of these products. All this information is available on the very informative Interlux web site: as well as the product information booklets available at Interlux Yacht Paint Center dealer stores.  Please wear protective clothing, masks, gloves, etc.


Bill Hooper is President of Hooper’s Yachts which is an official Interlux Yacht Paint Center.     

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