Safety
We’ve learned a lot about how Volatile Organic Vapors (VOC’s) affect the human body over the last decade, and none of the news is good. Only a few years ago it was thought to be OK to work all day bathed in fumes, wash our hands in paint thinner, and go home at the end of the day. Now we know we must protect ourselves with disposable gloves and vapor-absorbing filters, and wear coveralls and head socks to keep dust and spatters off our bodies. If you are about to begin a project and these things are unfamiliar to you, check them out in our catalog or web site. Get a hold of a good article or book on boat painting and learn from it. Follow this simple rule of caution: If you can smell it, you need more fresh air or the next higher grade of respirator mask.
Help is Available
We at Hamilton Marine, along with our paint and paint supplies manufacturers, want you to get the best possible results from the products we carry. You will find basic hints here in this article. For more specialized tasks, see the selection of books listed in our catalog or available on our website. Several of our major paint suppliers list phone numbers on their web sites that you can call during business hours for technical assistance. As always, feel free to contact us here at Hamilton Marine at 800-639-2715.
Preparation
More than likely, you’ve encountered the advice…whatever imperfections lie on the surface to be painted will only be enhanced by painting…so, get the surface right before you paint. Experienced painters will tell you that if the surface does not feel smooth to your hand, putting another coat on top will not fill in the surface imperfections or improve it. Careful and thorough preparation from the start and during each successive step is the secret to professional-looking results. And preparation, in many instances, is just another word meaning having the right supplies on hand and knowing how to use them correctly. You need an abundant supply of the proper grades of sandpaper, the exact thinner and wiping solvent recommended by the manufacturer and lots of clean rags to make the job go smoothly and to help you achieve a superior final result.
Primers and Undercoats
Paint chemistry has become enormously more complicated since the days when all that was required was to grind up some pigment and mix it with oil and thinner. Today’s paints are far brighter, tougher and longer lasting than those of even a few years ago. And today’s paints often require special surface preparation and specific additives to get the results you desire. So read the instructions, on the can—or printed literature, if available– making sure to have exactly the right products on hand to complete the step-by-step process. You can always find people around boatyards who will tell you to take shortcuts, like substituting materials or painting when it is colder or hotter than recommended. Unless you are sure they are correct, why be part of a “lab” experiment?
Choosing the Right Paint
One-Part Polyurethane: The most popular topside and deck paint choice, this is the one we recommend most highly. We consider it ideal for do-it-yourselfers who can achieve near-professional results with a brush or roller (or both, as with rolling and tipping). Even though it’s not quite as hard or durable as two-part polyurethanes, many professional painters find it close enough in appearance that they prefer it to all other enamels.
Alkyd Enamel: This traditional oil-based paint is easiest for the amateur to apply using a brush. Still very popular, it is more compatible with underlying surfaces, more economical and doesn’t require as much fuss as polyurethanes; however gloss and color retention are lower. For the traditionally planked wood boat, alkyd enamel is a good choice for dealing with the expansion and contraction of wood. Also, its oils are chemically compatible with the wood’s natural oils.
Two-Part Polyurethane: This is the hardest, highest-gloss, most durable paint available. Some can be brushed or rolled but others must be sprayed. More attention is required for surface preparation and priming than for one-part polyurethanes, and they are generally more toxic, especially when sprayed. Some two-part polyurethanes will “lift” oil-based paints, so check for compatibility with the paint that’s now on your boat. Most manufacturers recommend application by professionals only. If you decide to go it on your own, visit the manufacturer’s website and follow their advice to the letter.
Paint Application Tips
Remember cleanliness. Between each coat, oil and dirt residues must be removed. Refer to the manufacturer’s recommendations. Some prefer dishwashing detergent and water; others wipe down with a compatible solvent wash. Plan ahead so ample drying time is allowed after each step.
When applying paint over epoxy, allow the epoxy to cure at least 7 days (10 days is better) and remove the amine blush from the surface of the cured epoxy…even non-blushing epoxy. Warm fresh water will do this just fine– be sure to allow it to dry. Compatibility issues still pop-up between paints and resins even when these steps are followed.. If you have any concerns, no matter how small, consult with both the epoxy maker and the paint maker.
Don’t apply paint when it’s windy, wet, foggy, snowing, or late in the day. Forming dew can turn a high gloss paint job into a satin nightmare. Waiting an additional day may save you from re-doing a failed paint job.
Heed what the manufacturer says about the temperature at which the paint can be applied. Most manufacturers suggest a 50°–80°F range. Professional painters can compensate for temperature variations and can change a paint’s drying characteristics using thinners and reducers, but that’s risky business for amateurs. Drying may also be slowed by a relative humidity above 65%.
Wear protective clothing, especially respirators and eye and hand protection, when dealing with toxins and strong chemicals. Provide adequate ventilation, and keep all products away from sparks and open flames. When the job is complete, wash sanding residue and solvents off of you immediately.
Read the instructions on the can again. It sounds simple, but it can prevent you from overlooking a small tip that can make a big difference.
Good brushes are like good shoes and shirts: they may cost more initially, but they are a pleasure to own, last longer and work better than cheapies. Use less expensive brushes for projects with resins and bottom paint and where the final finish does not matter.
Use Fine Line tape to ensure sharp, clean divisions between colors. Although more expensive, its thin profile, sharp edges and better adhesion will do a much better job than other tapes.
Stir—do not shake—enamels. Bottom paints need to be shaken because their heavier contents settle, but shaking topside paint causes bubbles that hinder the application and cause blemishes in the final finish.
Clean the surface with a tack rag to remove the last vestiges of dust and residue immediately prior to painting. If you use a solvent wash, allow it to evaporate completely before painting.
Applying the Paint
- Paint will hide underlying color, but not texture. How many coats and what type of paint you use will be important. However, the use of sealers, sanding surfacers, putties, and sandpaper will have as much to do with your final results. Be aware of proper application techniques and cure times for the products that will be applied to the surface to be painted.
- Always observe appropriate drying times between coats of paint. This means paying close attention to labeling on cans and manufacturer’s instructions.
- All surfaces should be lightly sanded between coats, and especially prior to applying the finish coat, unless otherwise recommended by the manufacturer. Sanding smoothes-out the surface, fills-in small blemishes, and sets-up the surface for proper adhesion of the next coat. We recommend hand sanding, lightly. Consider a sanding board for large faired surfaces. A power sander is not recommended as it can load-up the sandpaper very quickly, polish the surface, and generally make a mess very fast.
- Multiple thin coats are far better than one or two thick coats. However, applying a film that is too thin may result in uneven gloss or visible brush marks, so always strive to get at least good coverage. For the first coat this may not be possible, so plan on at least three coats for your application.
- Brush or roll paint in one direction without interruption. Paint should be spread evenly and as quickly as possible to a uniform film thickness. Rolled paint will generally leave small surface bubbles or footprints. If you desire a smooth, high gloss surface, immediately draw a dry brush at right angles to the direction you rolled on the paint (if you rolled up and down—then drag the brush from right to left, for example). Work in small areas…maybe two feet wide, from gunwale to waterline…and work fast, not going back over your work. New paints applied this way (rolling and tipping) dry to tacky very rapidly; going over the area you just painted will likely damage your work.
- When you notice a thin spot or a dry spot, resist the temptation to go back over it. Wait for the next coat to cover it completely.
- If spraying is the desired application method, please refer to the manufacturer’s instructions. A top-quality spray finish requires proper materials, lots of painting experience and professional equipment. Most spraying is done by maintenance yards and experienced professionals, not by recreational boat owners. Spraying creates a myriad of environmental and health hazard issues, as well.
Cleanup
You can reuse leftover paint in a can if you cover the surface with a layer of plastic wrap to prevent a skin from forming—however, that’s a bit messy. You can also seat the lid of the can firmly with a rubber mallet or other soft instrument and store the can upside down (displacing the air to what was the bottom of the can.) Also, Hamilton Marine offers a nifty oxygen-blocking product, called Bloxygen, that is used to displace the air in a can, replacing it with nitrogen, effectively preventing paint and varnish from skinning-over in the can. It comes in a small, pressurized container about the size of a spray paint can.
Clean your brushes in used paint thinner that has been left undisturbed in a can. Thinner allows paint solids drop to the bottom of the can and can be reused many times. Use clean thinner for the final rinse. Wash brushes in warm soapy water (dish detergent works great) and rinse out, then wrap with a paper towel to help keep the bristles aligned. You can also keep the brush suspended in clean paint thinner, in a covered container—ready for the next use.
