Re: Paint question for above waterline
Here's an article that may be of some interest to you:
Applying Polyurethane
by Don Casey
The reason it?s called a mirror finish. Polyurethane paints allow for staggering good looks.
Call me unlucky, but Olga and I just experienced the eye of a hurricane for the second time in ten months. This is not from reckless behavior?we were south of the so-called hurricane belt both times. How this relates to the subject at hand is that I have seen a fair amount of damage assessment lately and in nearly every instance one of the big-ticket items was painting.
So let?s talk about putting the gloss back on a damaged or aging hull. If the insurance company is picking up the tab, by all means insist on the best professional you can find and from him or her demand perfection. Since a bag full of money is going to change hands here, you should get the kind of finish that dazzles, unmarred even by a blemish only you would notice. Likewise, if your index fund is finally off life support and breathing unassisted, and you want to celebrate by spending some of your new-found wealth on your boat, find yourself a paint-gun wizard. My regular readers will know that I put beauty at the top of my list of boat-selection criteria. Allowing that beauty to fade causes the relationship between owner and boat to also lose vibrancy. Nothing restores a boat (and the pleasure of owning her) more dramatically than a fresh mirror-like finish on the hull.
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"There are just four requirements for getting a perfect finish."
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What about the rest of us, those unwilling or unable to part with $150 to $200 per linear foot to have our hulls painted? Must we resign ourselves to dull boats and discontented lives? I think not.
Here is the formula. Painting the hull yourself with a roller and a dry brush cuts the cost by more than 90 percent but diminishes the result by less than 10 percent. It is one of the few bargains we poor sailors ever get. And if you are unwilling to settle for an ever-so-slightly less than perfect finish, you can make up that deficit and more by perfecting your technique and waiting for the right atmospheric conditions. The slower solvent used for polyurethane applied by roller can, in fact, deliver a gloss level superior to that typically achieved by spraying.
Don?t take my word for this. Invest around a hundred bucks in a quart of two-part polyurethane, a quart of thinner, a fine-finish roller cover, a $20 badger-hair brush, and some tray liners, mixing buckets and stirring sticks. Unless you have a reason to select a different paint, you are likely to get your best results from Interlux Perfection, which is formulated for do-it-yourself application. Now go paint something.
To get a feel for what the paint is capable of, the best practice surface is a piece of glass?window glass, not fiberglass. Painting glass means that all flaws you see afterwards are in the paint, not the underlying surface. Stand the glass up to simulate the vertical orientation of your hull topsides.
Polyurethane paint jobs are like any other kind of paint job in that the brunt of the work is surface preparation.
There are just four requirements for getting a perfect finish. The first is the right tools, which you already have as long as you bought a solvent-resistant foam or mohair roller cover and a first-quality badger-hair brush. The second is perfect surface preparation, which is going to be where you spend your time when you actually paint your boat but is a non-issue when the surface is clean window glass. The third requirement is low humidity. Two-part polyurethanes are moisture sensitive, and you will not get stroke-free flow-out if the humidity is above around 65 percent. Painting only on dry, cool days and not in direct sunlight allows the paint to flow out water-smooth. The fourth requirement is exactly the right amount of thinner in the paint, and this changes slightly from day to day depending on the weather. The trick to getting the thinner right is to sneak up on it, which you can do without risk when practicing on window glass.
Keep in mind that this initial effort is only to make a believer out of you, so all you are after is a foot square of high gloss, stroke free finish. A quart is good for about 125 square feet of coverage, so start with two ounces of base mixed with an ounce of curing agent. This is way more paint than you need, but some additional paint is required to wet out your roller. By the way, you would be wise for this experiment to cut a 9-inch roller cover into thirds and buy yourself a three-inch trim roller frame. This will let you get three practice sessions from a single roller.
Interlux Perfection paint is a new formulation, replacing Interthane Plus, and in some conditions this paint can be applied without thinning, but you should expect to get better flow by thinning the mix at least 5 percent by volume. That means you should add about a teaspoon of thinner to your 3 ounces of mixed paint. Record exactly what you do, including the temperature and humidity, to give yourself a better starting point for future mixing.
Pour your mixed and thinned paint into a small paint tray, load your roller, and apply this paint to the glass. Immediately draw your dry badger-hair brush horizontally across the paint application, using the lightest touch possible. Now wait. If after about three minutes the brush strokes are still visible, you need more thinner. Tilt the tray to collect the paint into one corner and add just a few drops of thinner. Stir, reload your roller, and paint on a fresh test square. Keep thinning, painting, and waiting until the brush marks disappear.
Let?s see, a $150 a linear foot times 35 feet times both sides of the hull? Applying the paint by hand won?t break the calculator or the cruising kitty and, with some experimenting out of the way first, can bring just as good a finish.
If the paint runs, sags, or curtains on the glass, you have added too much thinner. This requires mixing additional paint to correct, so you want to try to develop a sense of when you have added the maximum allowable amount of thinner. Too much thinner will also rob the paint of some of its gloss, so it is better to err on the side of not quite enough.
When the paint flows out as smooth as the glass underneath, you have the mix just right. The more important result is that you now know what quality of finish YOU can achieve with this paint
If you are using a light color, you should also roll a test area without tipping it out with the brush. Pigment inhibits the flow of dark colors, but white and light colors can often be applied without tipping, giving a glossy finish with a very slight texture that many find quite pleasing. If the rolled-on only finish satisfies you, it makes the real application that much easier.
You are almost certain to be astonished by the appearance of your very first try with this paint, but if you are not satisfied, do it again?and again?experimenting with both the mix and the application until you get the result you want. Only then will you know you can get a similar result on your boat. But don?t go from the glass pane to the boat. There is more to rolling and tipping than painting a single square. Find yourself a dinghy or a dock box and paint that first, learning how to maintain a wet edge and how to tip the fresh section without marring the section behind. By the time you have done that, you will have made most of the learning mistakes and you should have in hand both the technique and the confidence that will allow you to get a spectacular result painting your hull.
All you?ll need is a couple more quarts of paint.
