Some thoughts about finishing (long)

[Barry Pyeatt]

Some thoughts on finishing. I'm not talking just about getting it in the water to use it There are many approaches to a good finish, but here are some thoughts about how I go about it for anyone that may be interested. :roll:

I hope that this brings out any number of comments and additional tips from others. As there are many variations to consider as well as a lot of different thoughts and opinions. I also use other approaches and techniques depending upon the needs and desire for the level of finish that I want to achieve. There are lots of valid arguments and approaches, but this is just a series of thoughts that have brought extremely good results for me for years. :wink: I have tried to base this upon minimal tools and something that the average builder can do without sophisticated spray or finishing equipment. But it does require a bit of attention to detail and anyone can do it that wants to take the time and the care to accomplish a good high quality level of finish.

If you want a good finish, (better than just putting paint on), it is all in the preparation. And that takes time. There really are not any good short cuts to getting prep work completed. Paints and other finishes need something to bond to if you want good performance from them. The surface to be finished needs to be clean and free from any contaminates that can affect the paint from adhering or drying/curing.

All too often, the tendency is to go to far in sanding the surface before applying the primer if painting. Again, you need something for the paint to adhere to (grab onto) for a mechanical bond. So sanding with anything to finer than 120-150 grit will make it too smooth for the primer to do a good job and 100 grit is really about smooth enough for primer to make a good base.

One thing to be pretty careful about with softwood plywoods is the tendency to want to sand it all smooth. The difference between the annular rings and the growth rings is so great that you will remove the softer wood and leave the harder rings proud of the surface with too much sanding. That will make a flat or even surface uneven and the more you work it the worse it gets. So don't over do the sanding in preparation for the finish. If fillers are needed to bring the surface to the needed level then they should be applied and feathered out over a broader area and then sanded down to the finished level. The more evenly you apply the fillers, the less work is involved in bring them to the finished level.

Again, don't over sand them or try to make them too smooth. Fillers don't have grain so they sand down evenly. A sanding block, ROS or a long board will do a good job if you don't overdo it. I like using the sanding grids as they don't clog up as you work. Again anything beyond 120-150 grit is overkill and will not help your finish.

This isn't a tutorial on sanding/prep work but rather on finish work after sanding. In partiular for paint to be applied. For varnish work, the steps are similar up to the point where the first coats are applied. Then we obviously are not working with primers or paint but varnishes instead.

Once you have the surface ready to finish, vacuum the entire surface with particular attention to crevices joints, hidden surfaces and seams. Then using a tack cloth wipe down the entire surface to remove any residual dust or debris. If dust is filling a crevice that needs to be flush, brush it out, vacuum it clean and then fill it and sand it flush. Then repeat the vacuum, tack cloth wiping of the entire area again. Once your tack cloth comes up completely clean, you are ready for primer.

Try to work in as clean an area as possible with no standing dust or debris. Lay out large poly painters tarps to help keep it a clean environment to work in. It is a good idea to hang poly tarps to close off the area being worked in to keep things from drifting into and onto the wet surfaces. Remember too that there will be water involved in the sanding so you want to protect the surface below. I would not recommend working in the direct sunlight. It can cause any number of issues to occur while you are trying to apply and work with the finish. But it is important to have good light to see uneven surfaces and even applications of materials.

The first coat of primer can be brushed, rolled/brushed or sprayed. You just need to get it onto the surface and into all the nooks and crannies to seal the surface. Brushing with the grain on the final sweep of the brush will help but is not so important on the initial coat.

I like to use good quality primers with lots of binders and pigments. They can be Alkyd (oil) based or latex, it really doesn't matter which you use regardless of the type of finish paint you are going to use. (Assuming you are using house paint or one part polyurethanes). I use the better primers, unfortunately they tend to cost a little more but you get more primer pigment in the can and on the surface so I think they are actually less expensive.

I like the Ace Hardware Exterior Oil based primer because it has a high pigment content and doesn't cost as much as most others. It is also very sandable which you will see is very important to a good finish.

My first coat of primer is always white. It allows you to see where the uneven areas are that may require more work and it provides a complete coverage of the material. Subsequent coats can be tinted so they contrast to the first coat so you can tell when you have sanded thru a layer and they reveal high and low spots more easily.

Then I give the primer plenty of time to completely setup and cure.

Not allowing the primer to completely dry before sanding will clog the paper and give you uneven prep. Once the primer goes on the technique I prefer will use "wet" sanding to prevent the paper from clogging and to remove the particulate from the surface as you are working. It also allows you to visually see the areas that need more work a lot easier.

I use a wet/dry paper or a sanding grid on a long board or block at this stage. I will also use the foam sanding blocks on uneven or curved surfaces. Usually 120-150 grit and all I am doing is evening off the surface so it doesn't have brush marks and taking down the raised grain if it is bare wood. If it is epoxy or resin I'm trying to just even off the tops of the highest points. Often times most of the primer will appear to be removed in this step but I try to not take it docompletelyely bare wood or to go completely thru the resin or epoxy to the glass fiber.

I pay particular attention to the hard to get to places and edges to be sure I am not leaving things unsanded or taking it too far at this stage.

Then it is wash it down with warm soapy water and then vacuum time and tack cloth again until the cloth comes up clean.

My second coat of primer is usually tinted light gray. Black pigment (tint) is squirted into the primer and mixed completely until it is even. Then the primer is strained thru cheesecloth into a working pail to apply it to the surface. That removes any small lumps or hard particles. That is then applied, brushing it on, rolling/tipping or spraying. Again I allow it to setup and dry completely before working on it further.

The surface is now a lot more even than after the first coat of primer as we have removed any raised grain and evened out the surfaces so they are looking a lot better. Occasionally some further raising of the grain will occur with this coat in some areas that were sanded thru on the first coat. That is fine. We want that to happen. The highs and low spots on the surface will have a fresh coat of primer on them and appear a little more even. Now it is time to get serious with the ROS, long board or large sanding block. Again with wet/dry paper we are going to wet sand the entire surface with clear water as the vehicle. Long sweeping strokes not concentrating on any given area. We want to remove the high spots of primer and leave the low spots. Uneven areas will become immediately apparent. Ripples will look like waves. White spots will suddenly appear in the gray field denoting where the high spots were. Then wipe the entire area down with a wet cloth to clean off the residue. Dry it with a dry cloth and let it air dry.

Then it is inspection time. Time to see where the areas need work. Some areas may need additional filler because they are obviously too low and impractical to sand down the high points to match. Some of the high spots may be able to be sanded down a little more to even them out without going too far. Again I try to not go thru the white primer coat.

I would then work on the areas needing attention, filling, sanding, using a long flexed metal straight edge to check for fair surfaces as I move it across the surface of all the areas that I consider important to the final finish.

Once that had been accomplished and I feel it is ready for more primer, I will again wash down completely, vacuum and tack cloth again until no residual comes up on the tack cloth.

I let it dry completely after this to assure that there is no moisture left in any cracks or joints.

Then I mix up a darker gray primer by adding more black pigment (tint) to the lighter gray primer and mix again.

Then strain again thru several layers of cheesecloth or a fine mesh strainer into a clean working pail. I will apply this coat with a brush or spray it on with as even a layer as possible but with a moderately heavy coat of primer. I will tip out any areas that had excess primer applied so that they are even. Then let it dry completely before doing anything to it.

At this point it should be a very even, level and relatively smooth surface. I will take the long board or large sanding block and using 150 grit sanding grid or wet/dry paper will go over the entire surface with long even strokes to check for evennesss I will go down as far as the lighter gray coat on high points but no further. Any remaining low points will show up in the sanding. Adjacent areas that are high and have darker gray primer can be sanded with long even strokes to bring them down some. But don't go thru the lighter gray primer coat that appears. Edges should be carefully hand sanded to be sure they are even and that they are ready for paint. Any pin holes or small shallow hollows can be touched up with a small brush and the darker gray primer and let dry. Then lightly sanded to even them out. I will again go over the entire surface with a flexed metal straight edge to check for fair surfaces. And fix anything that still needs attention.

When all of this is completed, I will again wash it down, vacuum and tack cloth it.

If there are still areas that are lower than the desired finish coat, additional coat(s) of primer may be needed. I will tint these final coat(s) of primer to approximately the same color as the final coat of paint will be. If it is dark blue, then the primer gets tinted dark blue or dark blue/gray. If it is a light color, then tinted to approximately the same color as the finish coats of paint. Not exactly, I still want there to be a difference that can be seen easily.

If the surface needs more than one or two additional coats of primer on them to bring them fair, then I will use a contrasting coat(s) of primer first so I can see the differences as I sand them out. I have had instances that have required 10-15 coats of primer and fillers to bring the surface fair and be ready for paint on some jobs. The low points look like growth rings on a piece of plywood from all the contrasting coats of primer, but the low spots are eliminated and brought even with the other surfaces. The contrasting coats of primer make the differences a lot easier to spot as you work. Just remember what color is below the next layer.

Depending upon just how fine a finish you want to achieve will determine just how far you want to go with the primers and filling.

At no time have I gone beyond 150 grit at this stage.

Then I will spray the final coat of primer on the entire surface. It can also be rolled/tipped. This is a fairly thin coat but evenly applied to completely cover the entire surface. Any areas that have a higher buildup are carefully tipped out with a good clean brush.

It is then allowed to completely dry. I then go over the entire surface with a medium-fine scotchbrite pad and clear water to just break/scratch the surface of the primer. It will remove any spots of spray that are high, any flecks of paint that have over sprayed and are higher and give me a ready to paint surface. I then rinse with clear water and let it dry completely.

Only at this point am I ready for paint.

Now, perhaps a word from me about why it doesn't matter if the primer is Alkyd or latex based. What we are after is the buildup of pigment. The Alkyd (oil) or water based latex is just a vehicle for holding the pigment in suspension while it is stored and applied. Once it is applied it will evaporate and leave the pigment on the surface. If you allow it to dry completely there is nothing left but the pigment and the binders that accompany it. When cured, it is essentially the same regardless of the vehicle used to carry it. We are after an even smooth (with tooth) base for the final finish to be applied to. But I find that the oil based primers are easier to sand than the latex binder primers.

If you are using a marine product to finish, then only use the primers and prep products recommended by the manufacturer of the finished product. Interaction between brands and products may result in a botched up finish job.

But here I am talking about using Gloss Exterior Latex Enamel or Deck/Porch Enamel or 1-part Polyurethane. Not 2-part LPU or other catalyzed finishes. Although the same prep can be used for the Epoxy Deck/floor finishes.

Once the surface is ready, mask off any areas that you don't want the finish to be applied to with painters tape and paper.

It is important to completely mix the paint being used for the finish. I can't stress this enough. Paint pigment (the part we want on the boat) will go to the bottom of the can and separate from the rest of the paint and the binders that hold it together. It has to be in suspension for it to be applied evenly. I use a paint stirrer on the end of an electric drill that looks like a little multi-blade propeller. It gets into the pigment and really breaks it up and puts it into suspension. I take a paint stick and scrape it off the bottom and around the seams in the bottom of the can. Then once mixed I will strain it into another can or container to work from. Never from the open paint can. I will pour out what I think I will need and then seal up the can.

The paint may be brushed on, rolled and tipped or sprayed and tipped. The brushes I use are the best I can find for the paint I am using. I have had mine for years and I take care of them. They have served me well and as far as I am concerned they pay for themselves in the ease of application.

The first coat of paint should be quite even and relatively thin. I want it to completely cover the surface and then let it dry. Dry completely. Then I am going to wet sand it with 220 grit mesh or wet/dry paper by hand with lots of clear water to keep the residue flushed off. I will end up going thru the first coat in some areas, it is unavoidable.

Then wash and let dry. I then take a tack cloth over the entire surface again and pay particular attention to the corners, crevices and not so apparent areas.

The second coat is then either brushed, rolled/tipped or sprayed/tipped and applied a little heavier than the first coat. It will begin to look like a finish coat at this point.

I let this coat cure completely before doing anything with it. At least 72 hours. Then I will wet sand this coat with a finer grit, such as 280 or 300. I don't go any finer than this because I am not dealing with automotive finishes or lacquers. I will check it for even sanding and appearance and then wash it down again. Then the tack cloth when dry. It should now be ready for the last and final coat of paint. I try to spray this coat if no others, but with care and a good roller/brush combination, you can roll/tip the final coat on and have a magnificent final coat.

The paints are all pretty self leveling as long as you get to them while they are "wet" and don't wait too long to tip them out. Then let it set up and carefully remove the masking tape and paper by folding it back and peeling away from the wet edge. Don't wait until it has completely dried or you will chip the paint edge as you remove the masking tape.

I would recommend that you not do anything further that would affect the surface of the paint for several days to let it all finish curing and drying.

After that, if you want to apply wax, go for it. But it isn't needed.

This type of application should result in a finish that should last for many years with only light maintenance. Wash it down with soft cloth and clear water when it gets dirty and rinse well and that is all that should be needed to keep it looking good. Avoid dish washing detergents as they will scratch the finish. If you have grease. oils or similar to remove a product such as Greased Lightning works well to remove it and then flush with clear water.

A word about paint. The better lines of paint are obviously more expensive primarily because of finer pigment grinds and more of the more expensive pigments and binders. You generally get what you pay for for the most part.

Cheap paint will for the most part not allow you to get a truly high quality finish if that is what you are after. And you use a lot more of it to get the same amount of pigment on the project. But it will certainly protect the wood from damage. With a little research and flexibility in color selection the closeout tables often offer some real deals on mismixed colors or closeouts.

Darker colors will be more apt to fade and go chalky on you over time. Same as on a home. Darker colors also tend to show up defects in the underlying materials/prep and finish a lot more than lighter colors. And they tend to show up the muck that occurs around moorages and launches a lot more easily as well.

White is used most often because it is easy to clean, doesn't show the chalkiness as it ages as readily and is bright and fresh looking.

A good Exterior Latex Deck/Porch paint or Enamel is available in any of the large Home Improvement stores. Many of them can be tinted to a desired color. Behr makes excellent products and I recommend them highly. But then so does Valspar, and several other manufacturers. Try to get fresh product. Most Mfg. will stamp a date on the can bottoms. It may be coded, but the local dealer knows how to read them. You want it to be shaken before taking it home but you will still want to stir it completely before using. There are specialized high build primers on the market, I have used them but don't find it necessary to pay for them under most circumstances. The better primers work well. Just keep them stirred and work from a paint pail or can not the can that they come in. Keep the contaminates out of the fresh product.

Good luck!

[Steve Downs]

Wow Barry, thanks for the lesson. It's nice to have a real craftsman on board. Thanks for sharing.

[Greg Luckett]

Barry,

Ditto on the thanks and the WOW!! It will take me several reads to really absorb these lessons, and then put them into practice. Since Sam's & Ben's Amphora project is the next boat, it should be a good starting place.

Thanks,

Greg.

[Mr. Scott]

I probably shouldn't comment the same way for fear of appearing banal, but, WOW! :shock: That was one of the best tutorials I have read. simply put, when the "simple" things are explained in detail to me the "harder" thing seem simpler! (hey it made sense to me)

[Jan Williamson]

Barry,

You should be writing a book. I enjoy your long posts, because it seems like I am right there as you are describing the process. Thank you for so generously sharing you knowledge with us.

[Dave Ruedel]

Great post, Barry!! I was lucky enough to have a friend who builds cars who gave me about the same tutorial after listening to me lamenting about my sandpaper lasting about 2 minutes before getting heat-lacquer/glass/whatever clogged. Your tutorial should be printed out by anyone who has not het gotten to that phase of his project.

[Greg Luckett]

Probably a dumb question, but how is the paper used wet? I have known that it can be for years, but have never seen it done and do not really have a clear mind as to how to do it. Is water misted onto the work or is the paper soaked, or????

Thanks.

[Barry Pyeatt]

Good quetion.

Well, first off it has to be Wet/dry paper, the regular stuff disintegrates in nothing flat.

I use a large sponge to put water on the surface and to wipe it down when it gets a lot of sanding residue in it. I use the same sponges that tile setters use for finishing grout. When they get dirty, toss them in the washer. Two buckets, one with clean water and one with dirty to rinse the sponge out. Obviously it doesn't get changed as often as it should. :oops:

This is fine on a flat surface, but we are working on just about anything but a flat surface. :? :idea: So...I will have a sprayer handy and spray a mist of water on the surface and keep it handy to keep things wet. I rinse off the paper or sanding grid often to remove any build up as well.

[Greg Luckett]

Another new skill to learn and apply

Thanks.

[Dave Ruedel]

Nice looking crew member you have there, Greg. Congratulations on reaching grandfather status.

[Greg Luckett]

Thankyou Dave.

Autumn is actually grandchild #4, my oldest son's second child. She was born Febuary 13th in the evening. Of course her granddad is enraptured by her already.....lol.

[Scott Dufour]

I was wondering if you can help with a disappointment, Barry.

I finally have gotten around to putting the first coat of primer (Benjamin Moore Alkyd based "Fresh Start") on a D4 I've been building this winter. It's about 55 - 60 degrees F in my basement, which is within the temperature alotted on the can. It just isn't drying, though. After about 24 hours it set up enough that it wasn't too tacky, but it scrapes of with a fingernail, and after four days I can tell it's still tacky underneath. My wife had used it about 6 month ago in 70 degrees and she tells me (after I put it on) that she had the same problem: it took over a week to set up firmly. Is this common with the Alkyds, or do you think I'm just doing something wrong?

[Barry Pyeatt]

Hi Scott,

Been there, done that, had similar results was very disappointed as well.

Don't know if it is the Benjamin Moore "Fresh Start" or what it is going over. Benjamin Moore products are high quality paints. As a primer this is one of the best for covering up other things that shouldn't be there or couldn't be removed. It should make an excellent base for finish painting.

I've generally had excellent results with Alkyd primers but a lot depends on what it is trying to attach itself to and how heavily it is applied and how it is applied. Temp range makes some difference as does the humidity levels. I generally paint in a booth, temp near 75 degrees at a minumum and we have a circulatory system that filters the incoming heated air and we can bring the temp up to about 85 degrees and let thing set. Our humidity levels are at or below 45% most of the time when we are painting. We also have heat lamps that can be set up in a controlled space to let things cure. So as a resuslt we can apply several coats of primer and sand them out and finish coats as well in a few days time.

At 55-60 degrees I wouldn't expect it to set up completely to the touch for about 72 hours or even longer. It will be dry to the touch on the surface but it will take some time for it to cure completely so it can't be scratched off.

I'm not familiar with your project....yet. But let me know some more about what it is being applied over, how it was applied and how heavy was it applied.

Meanwhile here are a couple things you can do to help the process.

Have a fan running to circulate the air somewhat. Don't blow it directly on the paint, but have it running on low with a furnace filter on the intake side so it filters anything out of the air while moving it. If you can get the temp up to about 65-70 it will cut the setup time almost inhalf.

Tarp off around the project and put a small space heater inside the tarped area. Don't try to dry the boat with it though, just warm up the space a little. Keep the air moving gently, it helps.

When applying Alkyds, I generally spray them with light coats which set up and cure very quickly even at about 60 degrees. I can sand and recoat generally in 24 hours

If I roll it on and tip with a brush, it will be applied considerably heavier and it takes a lot longer to set up. I would expect several days to be hard at 60 degrees and several weeks to be completely cured.

If it it brushed on, it depends a lot on how thick it is applied. But expect a longer period of time than spraying.

If it has a good primer under it, it helps. If it is sanded too well, to much finer than about 80-100 grit, it will take longer to adhere as well. Remember all the volatiles and carriers have to off gas and that goes a lot quicker if it is warmer. Once the surface gets hard, it takes quite a while for the material underlaying the surface to set up because it is more difficult to get the gasses out of the paint. The cooler it is, the longer it takes.

Don't panic though, it all will cure and set up.

Maybe this will help, If I know more specifics, perhaps I can give you more to go on.

[Scott Dufour]

Thanks for such a complete response, Barry. You are my new hero.

I think you nailed it. I'm applying over epoxy coated plywood, and I rolled it on with a cheap home depot roller for "smooth" surfaces. Last night I was betting it was a volatiles issue and that perhaps the skin that developed on the thick coat really slowed down the evaporation. I put some hallogen lights shining on it and was able, after about 20 hours, to harden up a small area slightly. I'm going to try the fan, keep the heat up, turn on the dehumidifier, and then exercise a lot of patience.

Since I can't spray, do you think I should cut the primer with mineral spirits to keep the coats lighter?

[Barry Pyeatt]

Actually you fit the mode of "Hero" more to me. I admire those that teach as a vocation.

I just share some of what I can that might help. Been there, done that enough that I've screwed it up just about all the ways it can be screwed up. So that should leave what works. :?

Primer shouldn't really be thinned. The "Fresh Start" is designed to cover over a multitude of " ickey" things and allow you to apply paint afterwards.

I would roll it out a little more when applying it. Also just don't expect it to dry instantly.

My dad's favorite saying when I was young and now one of mine as well.

"Patience my dear boy, patience!"

I presume you washed down the epoxy well to eliminate the blush before applying the primer?

[Scott Dufour]

I used System Three epoxy and haven't seen even the slightest signs of blush. I did wash it all down just to get all the dust off, though. I guess I'll just have to let it sit for a few weeks between coats. I'll use the shortest knap roller I can find and put it on as thin as possible. -- I started a B&B CS17 centerboard this week, so at least I won't have that awful feeling of nothing to do while I wait.

[Barry Pyeatt]

The only thing that comes to mind here that could be happening is the following:

1. Insufficient curing time on the epoxy final coat.

2. Not removing the "blush" with warm soapy water and a scotchbrite pad. Then being certain that it has been sanded (80-100 grit) to give the epoxy some tooth. Then wash with clear water and let dry.

3. Incompatibility between the System Three Epoxy Hardner and the Alkyd Primer.

It should be dry by now. Even at 55-60 degrees. But it can take 3-4 days at 77 degrees for it to set up completely. The combination of lower temps and higher humidity can cause it to take longer too.

It shouldn't be thinned, but it is best applied by spraying in thin even coats. Rolling it on will apply a lot more material and consequently take longer to set up. It will be dry to the touch, but the volitiles haven't had a chance to evaporate completely. Lower temps take longer obviously.

Yep, time to work on something else until it has set up. I wouldn't even think about attempting to remove it at this point. Let it set up and then wet sand it with about 120 grit and then recoat. The second coat will set up a lot faster.

This is from the System Three manual

Final surface preparation

Proper finishing techniques will not only add beauty to your efforts, but will also protect your work from ultraviolet light, which will break down epoxy over time. The most common methods of finishing are painting or varnishing. These coating systems protect the epoxy from ultraviolet light and require proper preparation of the surface before application.

Preparation for the final finish is just as important as it is for recoating with epoxy. The surface must first be clean, dry and sanded.

1. Allow the final epoxy coat to cure thoroughly.

2. Wash the surface with a Scotch-brite pad and water to remove amine blush. Dry with paper towels.

3. Sand to a smooth finish. If there are runs or sags, begin sanding with 80-grit paper to remove the highest areas. Sand until the surface feels and looks fair. Complete sanding with the appropriate grit for the type of coating to be applied-check coating instructions. Paint adhesion relies on the mechanical grip of the paint keying into the sanding scratches in the epoxy's surface. If a high-build or filling primer is to be applied, 80-100 grit is usually sufficient. 120-180 grit may be adequate for primers and high-solids coatings. Finishing with 220-400 grit paper will result in a high-gloss finish for most paints or varnishes. Grits finer than this may not provide enough tooth for good adhesion. Many people prefer wet sanding because it reduces sanding dust and it will allow you to skip Step 2.

4. After you are satisfied with the texture and fairness of the surface, rinse the surface with fresh water. Rinse water should sheet evenly without beading or fisheyeing. If rinse water beads up (a sign of contamination), wipe the area with solvent and dry with a paper towel, then wet sand again until beading is eliminated.

Proceed with your final coating after the surface has dried thoroughly. To reduce the possibility of contamination, it is a good idea to begin coating within 24 hours of the final sanding. Follow all of the instructions from the coating system's manufacturer. A good trick used by professionals, is to make a test panel to evaluate the degree of surface preparation required and the compatibility of the finish system.

Finish coatings

The function of a finish coating like paint or varnish over an epoxy barrier coat, is to decorate the surface and protect the epoxy from sunlight. In doing so, the finish coating extends the life of the epoxy moisture barrier, which, in turn provides a stable base that extends the life of the finish coating. Together the two form a protective system far more durable than either coating by itself.

Protection from sunlight is a primary consideration in the selection of a finish coating. Long term UV (ultraviolet) protection of the barrier coat depends on how well the finish coating itself resists UV and keeps its pigments, or its shield of UV filters on the surface of the epoxy barrier coat. A high gloss finish reflects a higher proportion of the light hitting the surface than a dull surface. All other thing being equal, a white (especially a glossy white) coating will last the longest.

Most types of coatings are compatible with epoxy. Thoroughly cured epoxy is an almost completely inert hard plastic. This means most paint solvents will not soften, swell or react with it. However, it is still a good idea to build a test panel to assure coating compatibility.

Coating types

Latex paints are compatible with epoxy and they do an adequate job of protecting the epoxy barrier from UV radiation. In many architectural applications latex paint may be the most suitable coating to use. Their durability is limited.

Alkyd finishes-enamel, alkyd enamel, marine enamel, acrylic enamel, alkyd modified epoxy, traditional varnish and spar varnish-offer ease of application, low cost, low toxicity, and easy availability. Their disadvantages are low UV resistance and low abrasion resistance.

[Scott Dufour]

Thanks for all the input, Barry.

Just an update on how things turned out on this project:

After several months of curing, the primer never really stuck to the epoxy as well as I'd have liked. I can't scratch it off with a fingernail anymore, but if pushed over a piece of smooth hardwood, it comes off pretty quickly.

Given that I built this boat to "get the newbie mistakes out" and for something for my young kids to bang around in, I'm not too concerned. I painted it with a high gloss Benjamine Moore exterior enamel, and I'm letting the kids have at it. It's luan and exterior douglas fir anyway; we'll see how long it holds up. I'll keep it under cover most of the time.

I think for the B&B CS17 that I'm building, I might go with a two part paint and a primer that is specifically designed for epoxy. I'm a little gun-shy now.

By the way - I don't recommend high gloss white paint for the interior of a boat. When the sun is shining, it is absolutely blinding.

Thanks again, Barry.

[Craig]

Scott, to add to Barry's excellent analysis I will offer one observation. When I built the Saralee I had the brown for the spar paint tinted to the color I wanted. That stuff never completely dried. I sanded down the club for varnish the other day and the bottom layer of brown was still gummy. That paint has been on there 4 years. The problem, according to my local "real" paint store manager is with the tint. It retards the drying severely. Since then I have only used pure colors with the oil based paints and they worked just fine. My paint area is 80-100 degrees and 75-95% humidity in the summer months.