Saturday 5 July 2014

Exterior Acrylic latex paint??

Tino is 72ft, roughly 23 metres long and needs completely repainting, we are going to need a decent amount of primer and paint, this is going to be an expensive job short and long term if we make the wrong choices.

We have already decided to use CPES from www.makewoodgood.com as our primer and their epoxy filler Fill it, while researching epoxy resins. primers and top coats I came across this website and an interesting section regarding the choices of topcoats available the pros and cons of each, one being the use of household 100% acrylic exterior paint as a topcoat pioneered by a Dave Carnell a Chemist and Coatings specialist.

What we know

The CPES acts as a primer and restorer by changing the cellulose of the wood dissolves into the sap, oil and moisture found in wood, when all the solvents have evaporated the topcoat should be applied, usually within three days, however it takes up to seven days to fully cure, the applied topcoat cures with the epoxy therefore creating a strong bond.

The article by Dave Carnell a Chemist and Coatings expert and an icon in the boating and marine world

When I bought my first yacht (27’ auxiliary sloop) for $300 in 1951 I quickly learned that if its for a boat,the same material costs several times as much as if it is for your house. Oakum was $1/lb. at the marine supply store;five pounds for a dollar at the plumbing supply store. Marine paint cost several times as much as house paint of similar composition. I worked for a major chemical company that also made paint and knew that their paint that made the most money and on which they spent the most on research was house paint. Houses are out in the weather all year-no winter cover or inside storage. Their owners expect to repaint them infrequently, such as every ten years or so. They also expect a good paint job will require little preparation before repainting. Back then the only house paints were oil paints, so my yacht was painted with top quality oil-based house paint.

All paints consist of binders or resins, pigments, solvents, and additives. The binder forms the film that sticks to the boat and holds the pigment there. The pigments color the paint, make it opaque and have a good deal to do with UV resistance. Solvents keep the binder dispersed or dissolved and the pigments dispersed in an easy to apply state. They allow the paint to be applied in the correct thickness and then evaporate from the paint film as it dries. Mineral spirits, a petroleum distillate fraction, is the most common solvent in oil-based paints. In latex paints, water is the major fluid. It does not dissolve the latex particles, but disperses them in suspension. Small amounts of special solvents are present to control the coalescence of the latex particles into a tough, tenacious film and to slow down the drying of the latex paint. Through the years latex paints have developed to the point where 100% acrylic latex paints are better than oil paints on all counts. They are more durable and tougher. They resist chalking and fading, retaining their color especially well when exposed to bright sun. They are easier to apply, going on more smoothly and with less brush drag. They have less tendency to grow mildew. They have almost no odor and no fire hazard. Cleanup is with water. They can be recoated in as little as one hour.
The 100% acrylic latex is the key to the outstanding latex primers and paints now available. The weather resistance of these polymers parallels that of the acrylic molding powders that make red automobile taillight and stoplight lenses that last forever without fading. I checked out all the top quality exterior primers, paints, and porch and deck paints at both Lowe’s and Home Depot-they are all 100% acrylic latex products. All of the products are available as custom colors mixed to your desire.


A posting on the rec.boats.building newsgroup on the Internet asked if latex paint was good below the waterline, as if it was going to wash off. Look around your neighborhood. All those houses painted with latex paintsit out in the weather all the time. My boats live in the water with their latex paint jobs. Platt Monfort recommends for waterproofing the Dacron® skins of his Geodesic Airolite boats “...the simplest method being a good quality exterior latex house paint.”How long is the latex paint job going to last? The 16-year old Uncle Gabe’s Flattie Skiff (Sam Rabl) built of ¼” fir plywood was painted when new and then about 9 years ago. It looks pretty scroungy, but the interesting thing is that while the paint on the wood has been scoured off by hurricane winds and general wear the paint on the epoxy-fiberglass joints in the sides is perfectly intact and looks great.


When I rebuilt my 1964 Simmons Sea-Skiff 20 I used a heat gun and a wide chisel to remove about a dozen layers of old oil paint. To repaint I used latex primer and then two coats of Lowe’s “Severe Weather” 15-year guarantee semi gloss latex exterior paint custom colored to match the “Simmons blue” that was next to the wood. It has been three years and three hurricanes ridden out on the mooring since the boat was launched. Except where the boat has rubbed fenders or the edge of the float and on the cockpit floorboards the paint is in first class shape. I do need to repaint the floorboards. In my survey I found that Lowe’s has an exterior 100% acrylic latex skid resistant paint (Skid-Not®) that can be custom colored. I believe I will try it.I am not alone in appreciating the outstanding performance of 100% acrylic latex paints for boats. Thomas Firth Jones, boat designer, boatbuilder, and author of Boats To Go wrote in Boatbuilder several years ago that he preferred latex paint over oil paint for boats for all of the reasons cited above. He did comment that he paints his tiller with oil-based paint because the latex paint stains there.I was talking with “Dynamite” Payson one May weekend a couple of years ago and he told me he was going to repaint his skiff with latex paint that weekend.Jim Michalak, boat designer and builder, uses latex paint on his boats.Phil Bolger reported in Messing About in BOATS that his personal outboard boat is painted with semigloss latex house paint.Boat builders are traditionalists and it has been a hard sell to get them to accept plywood, stitch-and-glue construction, epoxy adhesives, and other similar innovations. Don’t let tradition keep you from benefiting from the ease of application and outstanding performance of 100% acrylic latex paints.[This message has been edited by Dave Carnell (edited 12-15-2000).] 

A few replies from people who have also followed Dave's lead and their results

Just read your great article about using latex paint on boats.

I had a 40' sport fisherman and I painted it with white exterior gloss latex. Just cleaned up the hull real good and sanded any rough spots, then put the latex in a gun, cut it with a little water to thin somewhat, and shot the
boat and cockpit. That stuff is tough, and holds up very well. The nice thing is you can simply touch up any gator marks that occur. I ran it about 5 yrs on a basic coat, then finally did an overspray. Figured it would go another 5 yrs or so. Everybody thought I was nuts. I simply did what you did: pointed out how well it holds up on houses, fences, etc. Another nice thing is that, in many areas, it will touch up fine with brushes



Boating Forum Comments:


As is well known on this forum and around Cape Cod, I too believe in latex. Learned the trick back in the '60's from Spaulding Dunbar.

I was spot painting a repair just above the waterline at the bow. SInce it was low, it was more convenient to paint from an inner tube. One passer-by said, "You can't do that. The water will spoil everything." "'Zat so?" was my reply as I dipped my brush in the water next to me . . .

I'd heard about Spaulding doing that and always wanted the excuse to do it myself.

Fond as I am of latex, it's hard to get as absolutely perfect a finish as, say, Kirby. Those fancy hightek paints - Ironon or some such name - really do last eight to ten years looking good if you don't ding them. Regular paints should be good for three or four years if you don't bang the boat but many folk paint yearly anyway.

The latex looks primo the first year but when I go a second year she looks like she's thinking about a paint job. Third year and the paint does not look it's best at all. While latex will show a bump sooner than topside enamel, a booboo on the topsides can be fixed in minutes. Latex is so cheap, prep and application are so easy and clean up laughably simple that it's actually more cost effective to paint yearly than any alternative.
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FWIW, I used two coats of latex porch paint on the deck (glass over ply) of my old T-bird in Berkeley. It lasted three years for me, and three since (although the current owner doesn't use the boat much). A cautionary note, though: I first put on the second coat in the aftenoon, and heavy fog came in early. Most of the paint ended up in the bay, and I had to take nasty white drips off the blue stripe on the topsides. Kirby's is nicer, but more expensive and more work.
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My entire cabin structure is latex ... holds up just fine ... three years and counting. So easy to work with.
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How about latex over old oil based enamel. Bad? O.K?
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I'm doing it too, on cyprus planks. Works great and easy touch up. Does not give a perfect job, but she does not have perfect surface. Looks damn good though. I'm on about a 5-year repaint schedule. I also use a home depot flat latex porch and floor enamel in the cockpit. That does just fine, too. I'll be using it on the cabin roof next spring. I use Home Hardware's Best Exterior Latex.
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What about a clear latex sealer for brightwork instead of varnish? Any suggestions or experinces with that?
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Painted my Bolger Nymph dinghy with latex a couple of years ago and it still looks presentable. Even after being dragged in and out of a pickup bed and onto numerous beaches. I used an acrylic latex primer and semi-gloss topcoat.
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Two years on the topsides of AMANTE (50'Calkins sloop)in semi-gloss because I like the look. Not fond of the slick shiny plastic look of Imron or Awlgrip. The latex went over oxidized Awlgrip that had been sanded lightly and wiped with acetone. It holds beautifully. Also used the same semigloss on the non-skid portion of the cabintop. That has been terrific. Easy to clean and very, VERY tough. AMANTE is not a workboat. She has acres of varnished teak, chrome and brass. I constantly get compliments on her hull.

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Another believer here, thanks to Dave's advice. My glassed plywood Weekender looks wonderful with Glidden semigloss exterior acrylic latex.

My 24 year old fiberglass sailboat is ready for her first paint job on the hull sides, the gelcoat is now dull and thin. The local yard wants $5 grand for a first rate Imron job. No thanks. Anyone ever tried latex on old gelcoat?
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My 24 year old fiberglass sailboat is ready for her first paint job on the hull sides, the gelcoat is now dull and thin. The local yard wants $5 grand for a first rate Imron job. No thanks. Anyone ever tried latex on old gelcoat?
Is the gel coat too thin for a light cut and polish? I would try this before slopping paint on it.
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I refinished an old SUNFISH very nicely and latex sticks to fiberglass-epoxy butt joints in plywood through hurricane wind-blown abrasion that scours it off the plywood. In my experience, it goes on any surface that is sound.
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Thanks Dave, I may try the transom first to see how it does. The gelcoat on the transom is particularly thin where several names have been scrubbed off it over the years.
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My boats are in the water year round in NC. The paint is o.k. on the whole hull, but, of course, it is not anti-fouling. Owner of a houseboat in fresh water reported good service.
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Topsides is my only experience ... other than a small fishing boat. Did not work well below waterline on that boat.
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Topsides- it's AWESOME- cheap, long-lasting, easy to apply ... what else can you ask for with paint??
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You want to be sure to brush or roll coats of latex paint out well. Resist the temptation to put on a nice thick coat; it may lead to trouble.
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Dave, for what it's worth, a further note on thickness ( I agree with you). A painter told me to roll the latex on first, then brush it in with a good brush. My entire boat (45' ketch "Sea Witch") is now 3 years with latex over old oil (waterline up except brightwork), and as good as the day she was done. She is in water year round, all temps, and as everyone adds, soooo easy to spot repair.
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Dave, Saw your website and am thinking seriously about using latex. The boat I'm building is a 14' glued lapstrake, sealed inside and out with 2 coats of epoxy. I plan to paint the outside and finish the inside bright. It will be a trailer sailer, stored out of the sun, but all the water around here is salt or brackish. However, I hose down the boat with a garden hose after each use so the salt residue doesn't stay on the boat. Will the latex stick to epoxy, and what surface preparation is needed? And is there something as cheap and easy to use as latex that I can use for a bright finish?
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The System Three person I talked to once said ALWAYS check oil based paint to be sure it will cure on epoxy but water based paint always will. Words to that effect anyway.
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I've used Latex on my live-aboard houseboat, it has been in the water for two and a half years, and the paint is still holding up. It is getting a bit dingy, perhaps I will re-paint next summer.
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Used the search feature to find this thread, and now think latex is the way to go for the deck (over epoxy on wooden Sunfish)... but what's best for below the waterline? I've read that oil based paint won't cure over epoxy? But latex doesn't hold up as well as a bottom paint. Other options?
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From what I've read here, oil paint cures fine over epoxy that isn't actively outgassing. So if the epoxy is FULLY CURED (which can take weeks depending on brand, application and curing temps), oil paint is a fine option for dry-sailed small boats. (Progressive Epoxy note - more on this topic elsewhere on this page)
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I've had good luck with Rustoleum non-marine paints on the EXTERIOR of 5 boats. So far so good...

What Thorne said about epoxy... I have waited days and days for rustoleum to NOT dry on a new epoxy surface (West 105/205fast). Rescued the whole job with an additional coat with a healthy blurp of Japan Drier.

No problem with Rustoleum on a fully cured epoxy surface. After sanding the surface, wash with mild detergent and water and let dry. This will clear the free amines that migrate to the surface and act as Rustoleum-Anti-Dry.

Jus my experience... (Progressive Epoxy note - more on this topic elsewhere on this page)
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Re: Latex Paint for Boats
It seems most of you who advocate using latex are using it on sealed/epoxied/glassed surfaces, or on cabins and such. I just can't believe it'l work on carvel planked wood, with the accompanying seam compounds and swelling/ saturation, especially at the waterline. What about cutting in the copper line? Over latex? What about times when (after a storm, etc) the boat has 10" of water in it and you don't get it bailed out for hours? I don't think latex will work for these situations.
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Re: Latex Paint for Boats
I painted my dory with latex house paint last spring. it sat in the lake all summer. the only place the paint failed was where i foolishly use some slickseam to fill a few gaps. elsewhere its like new. sat with water in it many times.



Priming options - on wood (plywood)/fiberglass/metal

Obviously, water based latex on metal surfaces is a no-no that will cause rusting on steel surfaces.

Latex paint in nice. Easy to apply, great UV resistance and color stability, open containers store well. Flat to semi gloss finish. Downside is that it is not as smooth or glossy as solvent based paints. This is often a plus on decks or cockpits which folks don't want too shiny in most cases. However, some people want vey slick, smooth, shiny topside hulls.

Exterior latex is designed to use without a primer. Imagine having to prime a large beach home prior to painting! That said, latex paints seem to like to go over a primed surface. The priming seems to give the latex a more stable surface to bond to extend the paint job. it is important to prime AND SEAL plywood (plywood boats) because a lot of ply woods will over time peel or 'check' with dampness/water damage. Sealing the edges of the plywood is especially important. For sealing, always use two coats to fill in thin spots, micro pinholes in the coating etc. Generally plywood is sealed and primed with solvent thinned epoxy (like our esp 155 or home thinned marine epoxy used for the rest of the boat construction. Our aluminum filled moisture cured urethane (aluthane) also works. Links to these products at the bottom of this site.

over epoxy
Latex goes over epoxy very well. In some cases it is best to wash and or sand the epoxy first (many epoxies - not our No Blush Marine Epoxy will 'blush'). That said I normally just paint over the epoxy without special prep. The first coat or two of the latex will show lots of paint brush marks on the slick and smooth epoxy. I have even seen wet latex applied over wet epoxy.

Decision made we are going to use 100% acrylic paint on the outside of the boat.

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