PAINTING EPOXY RESIN

 

 

"HELP, MY ENAMEL PAINT WILL NOT DRY!"

PAINTING OPTIONS / WARNINGS

FOR PAINTING OVER EPOXY

Painting epoxy coated surfaces - options and warnings

 

 

Coating options - painting over epoxy

Search the Internet and you will find boating forum posts asking why the enamel paint they put over is drying so slowly and still tacky after many days. The posters come from all across North America and the are using any of the popular marine epoxy from a range of leading vendors.

 


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Search the Internet and you will find boating forum posts asking why the enamel paint they put over is drying so slowly and still tacky after many days. The posters come from all across North America and the are using any of the popular marine epoxy from a range of leading vendors. Typical responses suggest things like: amine blush, epoxy is not cured enough, to add Japan Drier or Cobalt Drier to the enamel paint next time. None of these are completely on the mark. The problem appears to happen in warm, humid environments (with dew points maybe over 50 degrees or so). There is a different sent of conditions/causes for the same problem when the temperatures are cool. This topic is covered in great detail below (
Enamels over Epoxy).

Amine Blush - many brands of epoxy, especially marine epoxies use a curing agent that will 'blush' during curing in cool, damp situations. The result is a visible or not visible waxy film on the surface of the epoxy that affects the adhesion of anything applied over it. See our page www.epoxyproducts.com/blush4u.html. Our Basic No Blush (tm) and Premium No Blush (tm) are non blushing epoxies. The problem with the enamel paints not drying in not related to amine blush.


Epoxy Not Cured Enough - most epoxies feel hard or dry in a few hours but continue to cure and harden for about a week. Generally it is best to paint or topcoat epoxy within a few days of the epoxy application, before the week full cure period has passed. This way the solvents in the topcoat will combine with the not fully cured epoxy and product some chemical bonding as well as the normal mechanical bonding. Again, the problem with enamel paints are not related to epoxy cure times.


Japan Drier and Cobalt Drier - are additives often added to enamel paints to speed up their dry time. You can find Japan Drier at paint stores and Cobalt Drier at art stores. The Cobalt Drier works faster and better than the Japan Drier, but neither do more than speed up (a little bit) the extremely slow drying of enamels over most epoxies.


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The answer to the problem/question appears to be the use of nonyl phenol in the epoxy formulation. See our page on Nonyl Phenol . Probably 99% of all epoxies contain nonyl phenol. Our Premium No Blush (tm) marine epoxy and our Water Prime water-based epoxy primer does not contain Nonyl Phenol. Enamels will go over our Premium No Blush or Water Prime fine and dry at normal rates without problem.

Note the other coatings, such as spar varnish, latex paint, two part LPU coatings go over epoxies with nonyl phenol just fine. Only oil based alkyd enamels (which I like to use for boat hulls) have a problem. Sanding, soap or water washing the nonyl phenol based epoxy will not fix the problem.

So, if you plan to paint your epoxy boat project with enamel paint here are your options:


* Let the epoxy cure/weather for a long while (I don't have numbers but petty sure it means two months or longer)

* Warm (70 F or better) temperatures and sunny, dry skies certainly help and MIGHT speed the drying problem. It is about the only fix for an enemel over epoxy that will not dry. A fresh coat of more enamel over the not dry - still a bit tacky - enamel, will not help.

* Use a marine epoxy that doesn't contain Nonyl Phenol like our Premium No Blush


* Topcoat the epoxy with a coat of the Premium No Blush epoxy or our pigmented water based Water Bond epoxy primer or our aluminum filled moisture cured urethane - Aluthane (tm) -- see
www.epoxyproducts.com/aluthane.html

-- actually coating or priming a clear or mottled project surface is a good think. It shows defects, chips, etc. very clearly that are hidden or missed on the clear or mottled surface. You can fix those spots before applying your fancy topcoat. If you skip this step you will find and fix these defects after the first coat of your topcoat and then have to apply a second coat of that pricey topcoat. The end result is the same number of coats over the epoxy anyway.





Marine Boat Finish Options


1) Latex

* the great debate - the experts speak

* priming options - on wood (plywood)/fiberglass/metal

* over epoxy

2) Enamel

* priming options - on wood (plywood)/fiberglass/metal

* over epoxy

3) LPU

* priming options - on wood (plywood)/fiberglass/metal

* over epoxy

4) MCU

* primer or topcoat - on wood (plywood)/fiberglass/metal

* over epoxy

5) Spar Varnish

* priming options - on wood (plywood)/fiberglass/metal

* over epoxy

6) Epoxy

7) Water based epoxy

8) Water based poly or varnish

9) Gelcoat


10)
Oiled / waxed surfaces

 

epoxy



1) latex

the great debate - the experts speak

Latex Paint on Boats


Using latex house paint on boats is a subject that is sure to raise lots of debate. The original supporter of latex on boats was Dave Carnell. Dave was a chemist and coatings expert and an icon in the boating and marine world. His text on latex is listed below. I believe it was first posted in 2000. Sadly, Dave passed away in 2011. After Dave's article is a number of user posts debating the topic of latex paint on boats taken from a boat building / boat repair internet forum in the fall of 2011. It is posted here so that you can get the comments and thoughts of a number of boat folks on this topic.

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WARNING: Warning this article contains material that may be offensive if you think painting is more fun than boating.

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 thatsticks 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 paint
sit 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).]
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More from Dave Carnell :



I have for some time promoted the heresy of using 100% acrylic latex exterior house paints for boats. I received this a couple of days ago from a guy in Pensacola, FL.

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.

 


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This current page is all about:

PAINTING EPOXY RESIN

Painting epoxy coated surfaces - options and warnings

Coating options - painting over epoxy


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.

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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.


2) Enamel


Traditional oil based (alkyd) enamel paints are a favorite coating of mine. They brush on nicely, are inexpensive and work great for painting the old metal mailbox on a 75 degree, blue sky, summer sort of day. For use in cooler and wetter conditions many people will add a drier to the enamel such as Japan Drier (4-5 oz per gallon of enamel) or Cobalt Drier (about 6 drops per ounce of enamel). A product called Penetrol ™ is a paint conditioner sometimes added to enamels and other oil based coatings for smoother application (less brush drag).


Getting these 'oils' to dry in a wide range of conditions and over chemically active surfaces can be a challenge for the manufacture and a disaster for the end user. To get a glimmer of how complex the process is, here is a quote from an article on "Driers for Alkyd Coatings' in the Sept. 2011 issue of "Paint & Coatings Industry" :


Alkyd resins are prepared during the condensation process of saturated and unsaturated dicarboxylic acids with polyalcohols and oils. Different alkyd resins are obtained depending upon the type of fatty acid, oil and alcohol... Depending upon ho much oil is used in the cooking process, the resin may be a long oil type, a medium oil type or a short oil length.... During the low-thickness coating air drying process, an alkyd resin reacts with oxygen from the air, yielding hydroperoxides.... In the next reaction step, hydroperoxides form free radicals, starting the oxidative polymerization process.


It is all complex chemistry. So too is the curing of epoxies which extends out for more than a week during which time the chemicals involved can react with moisture and carbon dioxide in the air. Air temperatures affect the rate of chemical reaction in the epoxy and the evaporation of solvents in the paint.


over epoxy

BIG WARNING FLAGS with enamel over a fresh (less than a few months old) epoxy base. Most (not all) epoxies contain a chemical called Nonyl Phenol that will slow the drying of enamel to a crawl (tack for weeks!) under certain conditions. More on Nonyl Phenol .


CASE STUDY: Real Life examples and fixes.


During the spring of 2011 I painted the bottom of an epoxy and varnish coated boat with rustoleum brand enamel. The enamel dried fine over the spar varnish but not over the epoxy were it stayed tacky for days and days, until I dragged the boat out into the hot summer sun for several days. After a series of experiments I discovered the 'enamel problem' happened when applied to epoxies containing nonyl phenol (most epoxies do - our Premium No Blush epoxy does not). The epoxy surfaces were cured from several days to several weeks prior to the application of the enamel and still the problem existed. I suspect that given a month or so of epoxy 'cure time' the problem would not occur (or we would hear about this problem all the time).The use of additional drying agent additives into the enamel helped a little bit. Location of the tests was New Hampshire. Temperatures in the 60s, 70s, 80s with dew points always over 60 degrees.


In there fall of 2011 I repeated my testing. Temperatures where now in the 40s and 50s and the dew points also now well below 50 degrees. Surprisingly the problem with the nonyl phenol containing epoxies had vanished. It would appear that the issue is caused by moisture (high dew point) in the air. The enamel dried quickly on the hard non porous epoxiy sufaces and not so fast on high solvent based coatings/primers (including Kilz primer (tm) and spray can enamel - especially when applied thickly over masking tape). I think the slow drying in the fall tests is temperature (solvent evaporation) related.


Summary of Alkyd Enamel potential problems


Warm and Humid Conditions (dew point over 50 F?) - Stay away from epoxies containing Nonyl Phenol under the enamel which will impede full drying. Prime Nonyl Phenol surfaces with either spar varnish, aluthane, Premium No Blush epoxy (which has no nonyl phenol), or Water Bond - water based epoxy primer prior to an enamel topcoat.

Cool Fall Conditions - Stay away from High Solvent spray paints and Primers under the enamel which will impede full drying. Epoxies with or without Nonyl Phenol, spar varnish or aluthane prior to an enamel topcoat.



Rcommendations for Surfaces to be painted with Alkyd (oil based) Enamels (under entire range of conditions)


1) do project with an non - Nonyl Phenol epoxy (like Premium No Blush) - or topcoat the epoxy with our Water Prime (pigmented water based epoxy paint)

2) prime the nonyl phenol epoxy with Spar Varnish prior to enamel topcoat. Varnish is easy to work with and smells nice. Has UV protection for epoxies. Downside: probably modest (but more than suitable) adhesion and durability. Amber color.

3) prime the nonyl phenol epoxy with our aluthane aluminum filled moisture cured coating. Advantages: can be applied in vry warm or cold conditions, amazing adhesion/bonding, aluminum color shows flaws in underlying surfaces and when sanded high spots turn darker in color.



LINKS


Find Aluthane in our marine catalog -
Click Here .

Aluthane has its own web page - Click Here .

Marine catalog page for our Basic No Blush and Premium No Blush epoxy - Click Here .

Marine catalog page for Water Prime epoxy water based epoxy paint - Click Here .

Marine catalog page for our India Spar Varnish (cannot be sold in California) - Click Here .



3) LPU

LPU coatings are two part polyurethanes. (See our page www.epoxyproducts.com/lpu.html). They are high in solvents, user unfriendly to apply (best applied by spraying multiple coats), and very expensive (note we sell a white - LPU Marine - - Acrylic Poly UV Plus - and a clear version at hundreds of dollars less them the mainstream vendors). Cars are usually painted with 2 part LPU coatings.

They are tougher than 1 part paints. Their weakest feature is adhesion. They generally go over an fresh epoxy primer (like our ESP 155). Application is multiple thin coats over a non porous surface. They may not be available for sale in all places due to their high solvent levels.



4) MCU

MCU stands for Moisture Cured Urethane. Our experience is only with an aluminum filled MCU called aluthane (see www.epoxyproducts.com/aluthane.html) . It is a wonderful aluminum colored primer or sealer as well as a topcoat if you like its aluminum-silver color. It has amazing adhesion and other useful properties including application at low temperatures and a 300 degree F service temperature. Many people restore old aluminum small boats with this product. Use it on metal, fiberglass and wood.

Aluthane (and #7 Water Prime (tm) below) are both great over epoxy and is a suggested tie coat over epoxy and under traditional enamel paint which can have 'drying' problems when applied over most epoxies.



5) Spar Varnish


I really like traditional spar varnish (we sell one called India Spar Varnish - not for sale in California). Because of its high solvent levels it is only available in quart containers and not available in all states any more. it is best applied over a base of epoxy, which results in a win-win situation. The varnish likes the stable surface the epoxy provides and the varnish protects the epoxy from UV yellowing and damage. Plus, varnish brushes on nicely and smells good too!

Sometimes varnish, or varnish thinned with more solvent is applied over raw wood to seal it prior to painting. This makes it easier to strip the surface back down to raw wood should you decide to finish the wood 'natural' instead of painted at some future point (the paint pigments don't soak into the wood grain).



6) Epoxy


Epoxies are used as a primer, sealer, tie coat, barrier coat but not as a surface finish coating. Epoxies are not color stable and they break down with UV exposure. Also the thick and no easy or fun to apply.

;


7) Water based epoxy

Water based epoxies actually contain solvents in addition to water and may not be available for sale in places like Southern California where solvent VOC restrictions are very strict. Generally water based epoxies are used for floor coatings because they need to be applied thin in broad, open areas to allow the water (and solvent) to evaporate away leaving behind a very thin coat. Clean up is with water, like other waterbased coatings. Water based epoxies also make good sealers and base coats on concrete, wood and fiberglass. Their pigmented finish provides an even base coat color for uniform topcoating with other paints (or you can let the water based epoxy be your top coat / final coat if you don't need a perfect finish, say on the bottom of a workboat, inside a locker, etc.). Our product is called Water Primer (tm)- available in a medium gray color (other colors sometimes available - including boat bottom blue).

Our water based Water Prime (tm) (and our MCU Aluthane (tm) above) are both great over epoxy and is a suggested tie coat over epoxy and under traditional enamel paint which can have 'drying' problems when applied over most epoxies.



8) Water based poly or varnish

Water based polyurethanes and varnishes do not have a good reputation for durability when used on boats or exterior applications. In very moist conditions (submerged/in a puddle, etc.) they can turn white. They seem best in low humidity / low moisture situations.



9) Gelcoat


Gelcoat is the finish found on professionally build fiberglass boats. It is nothing more than the fiberglass polyester resin thickened and pigmented. It has a life of several years before sunlight damages the surface, then it is time to paint (You really don't 're-gelcoat a boat). Polyester resin is not 100% waterproof so it is not uncommon for osmotic blisters to form between the gelcoat and the rest of the polyester hull below the waterline. (see
blister4u). Often boats are painted with epoxy paint below the waterline to slow or prevent these blisters (see barrier4u). Some boat owners will remove the gelcoat below the waterline to prevent blisters.



10) Oiled / waxed surfaces


Oiled teak decks or linseed oil wood/trim is very attractive but takes more care than painted surfaces. The good news is that they never peel or chip. The bad news is that they can be difficult (impossible?) to paint successfully in the future. Generally epoxies will go over oily surfaces and appear to be fine, only to peel up weeks or a few months later. There is no way to know if you degreasing efforts are sufficient. You do your best and hope it works! Ditto for waxed hulls, fiberglass, wood or varnish finishes. Solvents don't really clean the waxes away, it just softens them and spreads them about. A rather crude test for oil or wax is to spill on water on the surface and see if it beads up.


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Products Mentioned here:


* Aluthane ™ - an MCU with its own page -
www.epoxyproducts.com/aluthane.html - found on the same page as the LPU Marine ™ coating in our marine catalog.

* India Spar Varnish ™ - find in our marine catalog - http://www.epoxyproducts.com/5_urethane.html

* LPU Marine ™ - find in our marine catalog - http://www.epoxyproducts.com/5_urethane.html

* Premium No Blush ™ - find in our marine catalog - www.epoxyproducts.com/1_marineresins.html

* Water Prime ™ - find in our marine catalog - http://www.epoxyproducts.com/4_epoxypaint.html

*


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Painting epoxy coated surfaces - options and warnings

Coating options - painting over epoxy

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