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Subject: glass boat painting &
maintenance
----- Original Message ----- From:
Secretaris
Cc:
'Al
Schonborn'
Sent:
Sunday, October 24, 2004 7:59 AM
Hi, Ellen,
Seems Al has passed
the buck again :-) OK, let me
give it my best shot. (Is this how Al gets all those wonderful essays
for his WIT site?) Let me start by stating I am not a painter nor a
specialist on paints. As an amateur painter, I did help out
others and have painted my
own boat. As a rule of thumb, I tend to follow whatever a manufacturer
tells me to do, but as a
professional engineer, I always try to find the details and
principles behind things,
a task much simplified by
the Internet nowadays.
I
think there are three things to consider:
Many discussions have been held and are still going on about this question. One of the aspects is always "What is a good brand?". I am not going to burn my fingers on that one. There probably are lots of fairy tales told by sailors who have had a bad experience with brand X. The truth is most likely that they did not follow the recipe prescribed by the manufacturer. With the modern paints, the two most frequently made errors are painting at the wrong temperature and/or the wrong humidity. These two errors are the main cause of bad results in my humble opinion. A question that is easier to answer is whether to use one-pot or two-pot paint. I think two-pot paint is only needed on a Wayfarer if you plan to leave your boat in the water all season. Two-pot paint is almost 100% waterproof because it does not have solvent that vaporises and leaves the coating slightly porous. On the other hand, two-pot paint is harder to apply because, once the components are mixed, there is a limited amount of time during which the paint can be used. So you need to work quickly. Another problem is the rollers slowly dissolve and you need to switch to a new one every so often (have lots of spares within reach). Tool cleaning is nearly impossible or very expensive because of the expensive special solvents needed. Be prepared to throw away your brushes and rollers after the paint has settled. One-pot paint is fine if you leave your boat in the dinghy park. Above the water line, I would always use one-pot for it is much easier to apply and get a good result. Though one-pot paint is slightly porous, this is only a problem below the water line. There is also Polyurethane (PU) one-pot paint. Actually, this is a two-pot paint but the second component, the catalyst, is water (I should say water vapour) from the air around us. Basically PU paints harden like two-pot paints and don't dry by vaporisation of a solvent. So PU sounds ideal, but unfortunately I have to disappoint you. These paints usually have some solvent to make them brushable. On the bright side, they have less solvent than conventional paints. That means they will probably be less porous than conventional paints. Another matter to consider is choosing a paint system that is compatible with the existing coating. Sometimes you need to apply an intermediate layer to ensure the new layers will stick well. All good brands give out free booklets and/or have web sites with paint recipes. The consensus amongst sailors seems to be to stick to one system from one single brand. Then the layers of the system are best matched. Also these booklets (or web sites) will tell you what system is best used on the existing one. If you don't know what is currently on your boat, the best (only?) solution is to sand it off until you are back to the polyester gel coat. Then you have a known situation from which to start. Another popular discussion is whether to paint wet on wet (previous layer still slightly tacky when applying the new one) or to have the previous layer fully dry and sand in between layers. Again I think it depends on the system you choose (see manufacturer's advice). So what are the good brands? Honestly I don't know. I could name some good ones like International or Epifanes but they are probably not available in America. Or perhaps they are but under another name. Akzo coatings, is a multi-national behind many well known brands. Basically the various brands are the same but marketing plays a role. When you look at the abuse car paint has to take, especially in winter, I can not imagine these paints are any different from marine paints. And with the many plastic parts on a car, similar sticking problems face both car and boat manufacturers. In fact, in our harbour two boats have been panted with car paint. These sailors used PU car paint at half the cost of their marine counterparts. This car paint is sold under another brand name but comes from the same mill (Akzo coatings). I can't help thinking the only difference is marketing, and I am probably right. How to apply Two-pot paint you put on using a brush and finish with a roller. Work quickly and stop before the paint gets tacky. Do not use solvents other than for cleaning your tools. Watch out for these solvents, they are almost all carcinogenic. Always work within the prescribed temperature range and below the maximum allowed humidity. Make sure there is enough ventilation, not for the paint but for your own health. If need be, wear personal protection like breath filters and eye protection. One-pot paint, including PU paint, is generally easier to apply. Add solvent to make it brushable. Only use the type of solvent the manufacturer specifies. This does not mean you need to buy the same brand. For example if White Spirit is the solvent to use, often there are cheaper alternatives available at your local DIY store. Remember that paint can not be made thicker, it can only be made less viscous. That is why almost all one pot paints are sold a little too viscous for use. The amount of solvent to add depends on your tools, the size of them and the way you want to apply it. Almost all paints are tixotropic: that means they will get more liquid under the pressure of the brush or roller. A larger brush puts more pressure on the paint and hence you can get away with less solvent (it is replaced by elbow grease). With rollers, you probably want the paint to be slightly more viscous than when brushing. And when spraying, you want a thin paint with a fast evaporating solvent. Try to get the tixotrosopy such that the paint thickens quickly (a few inches) behind your brush. Check if the brush stripes disappear before the paint thickens again. If the paint does not thicken a few inches behind the brush, it is too thin and you will also see lots of those awful hangers. Also try to limit the use of a solvent to minimise porousness of the paint. The solvent evaporates and leaves tiny holes, though this happens at a molecular level and these tiny spaces will not let any water through, they do allow moisture into the paint making it dull - or worse, making it come off over time. In short, the more solvent you use, the shorter the coating will last. Like with two-pot paints, be very careful with the solvents. Use them only in a well ventilated area and use personal protection, just in case. On my boat I have used PU paint. I have put the paint on with a brush, cross painted it to spread it over an area and finished it off with a roller to get a nice, stripe-less result. PU paint can be used for quite some time before it gets too tacky. Especially when you pour some in a working can or roller tray and close the lid as soon as possible. In my case, I was able to use the PU paint for about three days. Then it was all used so I don't know exactly how long an open pot can be used. Some left over in the second pot wasn't usable anymore after about a week. One painting tip you must remember: Always start at the gunwale (or at the waterline) and work towards the keel. If you run out of paint and you need to get some more, chances are the colour is slightly different but nobody will notice since the other colour is near the keel. How to prepare This is by far the dullest and most annoying part of the job. Yet it is the most important part. For a good result, you need to sand many times over. Start with rough sandpaper and after applying filler gradually start using finer wet and dry sand paper. Touch the boat with your hands all the time and continue until all depressions are gone and the surface is as smooth as a baby's bottom. Also look along the length of the boat to spot depressions. Don't give up until you get the perfect straight shape; that is when you think "This boat doesn't need painting anymore, this is as good as it gets". Trust me it gets better. And this is the one and only secret for a perfect finish. While the preparations may take many hours, the painting itself will take only a fraction of that time. Painting can be fun, provided the preparations are perfect! Since the boat is curved in all directions, power tools can generally be used only for the rougher work. The final sanding requires lots of elbow grease. It goes without saying that before you start sanding, you need to do all necessary repairs. Drill out rotten spots and fill them with filler compatible with the existing and new paint layers. Larger damage is best repaired with glass and epoxy. But I am not going to discuss that process here. The filler and (if need be) base layer, depends on the existing coating and the new paint system. Again I refer to the manufacturer's booklets to see what products can and cannot be combined. It is very important to plan your paint job immediately after winter storage when the hull is still dry. The best way to dry the hull is to leave the boat outside for a couple of months, exposed to the wind but protected from rain. This dries the hull better than when it is stored inside where the air hardly moves. Finally, try to work as clean as possible. Dust will ruin your job. Clean the working area before you start and clean it again after every job. In my experience, there is often more dust indoors than outdoors unless you have a purpose-built paint-hall at your disposal. But do not paint outdoors when it is windy. Then all kinds of rubbish blows on to your freshly painted work. What about anti fouling? In short, I hate it. It looks awful on a Wayfarer and serves no purpose in my humble opinion. Not even when you leave your boat in the water all season. Go for a swim and give the bottom a quick wash with a brush every few weeks. That will take away most growth. And also, I can't get rid of the thought that anti-fouling is bad for boat speed. A good tip here is to pull the boat on its side in shallow water with the main halyard (tie it to a tree) while you have it fixed at bow and stern. You can pull the keel above water before the water comes over the side. This way you can clean one side of the bottom. And by turning the boat around, you can clean the other side. It takes about twenty minutes to clean the whole bottom that way. Beaching her is even simpler, you can then put her on her side with by pulling one of the shrouds. Put the mast tip on the ground and put something heavy on the mast tip to prevent accidental righting of the boat with you under it. Upkeep Glass boats are easy to maintain. Provided the boat is well painted and in generally good condition. You just give it a good clean every once in a while and keep it dry during the winter. Some people like to put wax on the coating for a showroom shine but in practical terms, I don't think wax is needed. It does not increase boat speed or if it does, the effect is so small you won't notice it. Do not put wax on your deck. It gets too slippery. I lost my crew once during a race because of that. Others thought it was hilarious, but I thought it was dangerous. It also looks awful because the wax gets in the anti-slip profile where you can't get it off. This leaves ugly grey spots on your decks. More important is to check and repair the rigging. The rigging parts are the parts that wear quickest and tend to break when least expected. Maintenance schedule At http://www.wayfarer.org.uk/Technical/faq/wintermaintenance.html, there is a good winter maintenance schedule. Hope
this helps. Best wishes,
Ton
Jaspers (W5011)
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