Boat Detailing Like A Pro

Oxidation Test (top): No Oxidation: Mirror image of ruler reflected in the gelcoat. (middle) Light Oxidation: Bottle reflected in the gelcoat appears cloudy, showing the label, but you cannot read the type. (bottom) Heavy oxidation: Little or no reflection of bottle in the gelcoat.

Reviving your boat’s glossy finish and creating a factory-new appearance is surprisingly easy if you use the proper techniques. Follow these steps for a long-lived durable shine.

Gelcoat, the exterior finish on fiberglass boats, is a porous mix of polyester resins and pigments that must be sealed from the damaging effects of ultra-violet (UV) rays, salt, dirt and weather. Neglect it, and it becomes more porous, resins oxidize and what remains is a faded, dull finish.

There is no magic wipe-on, wipe-off remedy that removes oxidation and has a gloss that lasts a lifetime. Achieving a likenew shine isn’t very difficult, and doesn’t require a lot of extra work, especially if you invest in quality materials and tools.

Just four steps will help to achieve a factory-new shine: wash to remove all contaminants; mechanically repair the gelcoat by sanding or compounding; chemically bond a protectant to the gelcoat to protect from further oxidation; and maintain the surface to extend longevity of protective coating.

STEP 1: Wash and Gloss Test

Scrub the surface thoroughly with a quality boat soap and water using a wash mitt, abrasive Scotch-Brite sponge or a brush. Flush with freshwater. Don’t use automotive soaps or household soaps, which may strip the wax or damage the gelcoat. If the application instructions recommend using a certain cleaner with a specific protectant (i.e. wax) to obtain the desired finish, follow the recommendations.

Use the “Oxidation Test” at right to determine condition of gelcoat. For surfaces in good condition that only require rewaxing, go to Step 3. For oxidized gelcoat, wipe with a solvent to remove silicone, wax or glaze buildup. Spray the surface with water, which should wet out rather than bead if all finishes are successfully removed.

Two options for repairing oxidized gelcoat are: fill the cavities with a quality wax or polish (hereafter referred to as “wax”); or knock down the high spots, either by compounding or sanding until the surface is flat, then follow with a filler. Just applying a wax on heavily oxidized gelcoat is a short-term repair. The surface has sheen when viewed from the side, but no deep luster, and rain in time washes away the wax. Oxidized gelcoat, whether light or medium, is best repaired by compounding or sanding to obtain a flat surface, filled with a glaze (or wax if a one-step product), then followed with a wax.

One-step restorer and wax removes light surface oxidation and stains from leaves, bugs, birds and other fallout. Apply by hand with a microfiber rag or buff with a slow-speed 1,500 to 2,500 rpm sander-polisher or a drill and a wool compounding pad. As one-step restorers only offer UV protection for one to three hand washes, follow within a few weeks with a premium wax after thorough washing.

STEP 2: Compounding

If your boat’s gelcoat is looking cloudy or lightly oxidized, you need to apply a color restorer. Heavier oxidation requires more aggressive repairs, either by wet sanding followed by a finishing material (glaze), or use of a rubbing compound, then glazing. Take care when using compound. It’s an abrasive process that can damage the thin gelcoat, which is about 20/1,000” thick or the thickness of five sheets of paper. Frequent compounding can remove too much gelcoat, exposing the laminate underneath.

Color restorers and rubbing compounds don’t like heat. Besides being abrasive, they contain water and petroleum distillate or other lubricant that keep the liquids wet and prevents excessive scratching. If applied in the sun, they will haze and it’s too late for the product to work. A wax you want to haze; a compound or glaze you don’t.

Products that restore gelcoat color and gloss don’t provide a durable UV-protective coating. Whether it’s a one-step or two-step process, all products must be overcoated with a protectant wax after washing with boat soap, within a few days and certainly no longer than a week. You could wash then wax without waiting, but the wax wouldn’t form as strong a chemical bond to the gelcoat.

Buffing compounds are best applied with a wool compounding pad on a slow-speed sander-polisher or drill. Squeeze some rubbing compound on the gelcoat, spread it around with the compound pad, then buff. Use lots of compound to keep the surface cool. Heavily oxidized areas will require more compound. Buff an area about 15 seconds per square foot to prevent overheating (burning) the gelcoat. Don’t be too aggressive. Plan on less than 30 minutes to buff one side of a boat, for example. Compounding repairs the gelcoat, actually flattening the surface to reveal some shine but without any depth of image. With a rubbing compound, you will always have some color transfer to the pad.

STEP 3: Protection

Now that the gelcoat is repaired, you need to take the necessary steps to avoid oxidation from reoccurring. Protecting the surface with a quality wax that contains good UV protection is the solution.

Few modern waxes and polishes contain pure and natural compounds, but contain man-made ingredients instead. When properly applied, these protective “adhesives” chemically bond to the gelcoat. A wax needs heat over a prolonged period of time to bond to gelcoat. Ambient and surface temperatures, and the temperature of the wax are critical to achieving a strong bond. A boat baking in the hot summer sun could have a hull surface temperature slightly higher than the air, but on deck, surface temperatures could rise to 130º F (54º C) or higher. Under these conditions, the wax dries before it bonds to the gelcoat. When applied at cooler temperatures, however, around 50º F (10º C), the wax bonds, hard-ens and hazes, but it just takes longer.

The latest in high-tech polishes are easier to apply than waxes and last as long. Products containing Teflon provide a super low friction, non-stick surface that leaves a high gloss, dirt-repellent finish. Regardless of your chosen wax or polish, consider overcoating with Teflon Wax Sealer. Two coats thinly applied with a soft cloth dries to a hard, slick, non-stick surface that seals and protects and more than doubles the life of the wax.

Apply the finishing material in same manner as rubbing compound, except use a less aggressive yellow wool polishing pad. This glaze removes swirls from compounding and mechanically repairs the gelcoat to give a leveling and reflectivity that enhances the overall color and finish. The result is a high gloss finish that closely duplicates a factory-new appearance. There is no wax in this product - what you see is what you get! Within a week’s time, wash the surface and apply a quality wax to protect the gelcoat from UV damage.

STEP 4: Maintenance

A wax now protects gelcoat from UV damage, but with every washing the degree of protection diminishes. And if surfaces aren’t wiped dry, water droplets act as sunlight magnifiers that penetrate and break down the protective wax layer, once again exposing the gelcoat. A spray-on protectant helps maintain the wax coating by adding glossifiers to the wax, enhancing the shine and removing water spots.

Reserve a work weekend and use the proper tools and techniques to protect your boat’s gelcoat from UV rays, dirt, salt and other harmful environmental elements. The results are worth the effort.
- Story and photos by Jan Mundy
Jan Mundy is editor of DIY Boat Owner Magazine

This is an abridged version of the article that appeared in DIY Boat Owner Magazine 2002-#1 issue. The full version is found on DIY’s Hands-On Boater CD-ROM.