Marine Paint Sugestions

[alaska_av8r]

Re: Marine Paint Sugestions

That paint on that hiliner sure looks good. Nice job Bondo! I used Interlux Perfection last spring when I repainted my 30 footer. I made plenty of mistakes and was right at the limits on heat for painting with it. In my opinion it is not very forgiving and I am only sort of satisfied with it and would probably try awlgrip next time.

just my 3 sense....

 

[rickybenham]

Re: Marine Paint Sugestions

I am currently sanding, and will be painiting soon. Have a 16 ft SC. I will be running her in the saltwater of the puget sound here in WA does that make a difference for the paint selection, will post pics, she is a beauty 1964, gonna be a crabbin' machine.

 

[lowkee]

Re: Marine Paint Sugestions

Hey Skibum, gelcoat is porous on a microscopic level. Whyddya think everyone paints boat bottoms? Geeze.

I'm hardly a paint pro, but from my research and reading you are backwards in your statement. To answer your question, I'd guess people paint boats to avoid the hassle of gelcoating.

Gelcoat is perfectly fine, preferred even, for boat coating. Enamel paint, even multipart enamel, normally called 'topside paint', is not recommended for anything but trailer boats, as it will begin to blister within a few days in water. Paint, in fact, is not recommended as hull coating unless it is specifically made as bottom paint, which normally means it flakes off over time. Bottom paint is mainly used to allow for easy removal of barnacles. Urethane paint can be used topside or as bottom paint, but is much easier to scratch than gelcoat and does not flake off, so barnacle removal is not aided. In those respects, it is still is a second choice for durability and costs more than gelcoat as well.

Paint is, though, far easier to apply (by 'apply', I mean 'get smooth') than gelcoat. In all, gelcoat is the defacto standard for all boat building, since molds allow for perfectly smooth hulls every time. As a restoration coating, gelcoat can be time consuming in sanding due to its great durability. As a result, paint is sometimes preferred due to ease of application and sanding at the (hefty) expense of durability.

To compare the two coatings in real life, you often see 30+ year old, even abused, boats on the same gelcoat they were made with. Often even the most faded gelcoat can be shined back to original 30 years later with a good buffing. Painted hulls are lucky to last 5 years, possibly more if babied, and buffing them back is out of the question, since they will be heavily scratched by then. It is the trade-off we all make, but to say gelcoat is not recommended is to call every boat builder out there ignorant.

 

[Bondo]

Re: Marine Paint Sugestions

It is the trade-off we all make, but to say gelcoat is not recommended is to call every boat builder out there ignorant.

Ayuh,.... Whata load of Bull,..... Pure opinion,+ spin...

Shooting a coat of Gelcoat into a Mold, is totally irrevelant to Recoating an Old Boat....

 

[lowkee]

Re: Marine Paint Sugestions

Wow, Bond-o,

What a completely non-helpful "Nuh uh!" post. "Paint is awesome, look at this faded, scratched all to heck example. But it sure looked pretty on the first day!" Who is calling a post pure opinion and spin?

I'm painting my boat because I don't want to mess with gelcoat, but I haven't deluded myself into thinking just because I chose paint, it is better.

 

[Bondo]

Re: Marine Paint Sugestions

Ayuh,... The part I quoted is what I'm talking about....

The Ignorant boat builders are following build schedules for mold building fiberglass boats,...
While color durability might play into it,... Color Durablity is NOT their primary concern...
Waterproofing,+ getting the hull out of the mold Is...

Many,... yes Many brand new high-end boats come from the factory,... Painted....

Your aguement, Especially the last line, just doesn't hold water,.....

Wow, Bond-o,

What a completely non-helpful "Nuh uh!" post.

Really,... Squashing Misinformation is just as important as providing Good information....

 

[erikgreen]

Re: Marine Paint Sugestions

Wow, Bond-o,

I'm painting my boat because I don't want to mess with gelcoat, but I haven't deluded myself into thinking just because I chose paint, it is better.

Well, I think I'll jump in with another 2 cents worth.

Gelcoat is the best known coating for fiberglass hulls (so far) as far as durability and looks.

The big thing with gelcoat is that it's harder than paint... this is its blessing and curse. If paint goes on smooth and self levels (like many of the more expensive brands do) then it can come out shiny smooth when it dries. If not, you can sand, wet sand, and buff it.

Gelcoat can also be sanded, wet sanded, and buffed, although it's more like sand, sand, sand, sand, sand, sand, wet sand, wet sand, buff. It's harder and tougher than paint, get it?

Imagine if it were possible to coat a fiberglass boat in molten titanium without damaging the hull... how long would it take to sand that coat smooth and shiny? It'd be much easier if you did it in a mold, right? How long do you think it would last?

Paint is less durable, but much, much easier to apply in a non molded situation. Many people know how to spray paint fairly well, most modern marine paints are chemically formulated to give good results in a home or small shop environment (as in, not the boat factory). Gelcoat is gelcoat.

Gelcoat can be sprayed on , but even someone knowing what they're doing can get it too thin or thick. Plus you really need a gelcoat gun, not a paint spray gun (you can get by with a modified paint spray gun) It won't self level, and when it hardens it's a pain in the rear to sand.

Plus it's poly resin based, and the adhesion properties of that resin apply. If the surface it goes on is improperly repaired, then it can pop off. Poly is not a very good glue, it doesn't stick hard unless it's chemically bonded.

Gelcoat is designed to be the finish coat for molded fiberglass parts. You can make it work in other situations just like you can carve a boat from a big block of wood instead of planks and frames... few people want to go to that much trouble if they really understand what's involved.

Rare is the person who, working at home, can re-gelcoat a boat and have it look anything close to shiny. Oops! Here is an exception in a lot of ways, and he spent days (literally) sanding his gelcoat and making it fair and smooth. I believe he also had the gelcoat applied professionally, although it's been a while since I re-read his thread.

For almost anyone doing boat work at home, paint will give a better looking result. Careful choice of paint plus quality prep work will give a long lasting finish, up to 10-12 years for a daily use boat and longer if used intermittently (these are the sort of numbers claimed by Awlgrip and Interlux). This is longer than most people will own a boat, so it's effectively "forever".

So... if you're choosing to re-gelcoat your boat for the same reasons you'd repaint your car, think again... several times. It's not like repainting, it's more like you're fixing dings in your doors by taking the body panels off, pounding out the dings, sanding, wet sanding, repainting.... it's the long way around.

Unless you're either very ambitious and have a couple free days a week to work on your boat rebuild, you probably want to use paint. Really.

Erik

 

[NSBCraig]

Re: Marine Paint Sugestions

Gel coat is porous!

Why do you think they then paint on a barrier coat and bottom paint? It's to keep the gel from letting water into the laminate and resulting in blisters.

Blisters are caused in the laminate when uncured resin gets wet. The way to prevent this is by using vynilester resin or barrier coat and bottom paint. Since we're not building the boat in the mold and have no control over how the laminate was made, all we really can do is use are best judgement on what is best.

Paint does not blister unless the substrate is contaminated or you trapped solvent or some other error is application. Painted bottoms actually better because they are another layer sealing the gelcoat are better for keeping your boat in the water, but that all is a moot point once you factor in marine growth which will ruin either finish.


Gel coat is hard so it wears better so many prefer it where you walk.

 

[erikgreen]

Re: Marine Paint Sugestions

Gel coat is porous!

Why do you think they then paint on a barrier coat and bottom paint? It's to keep the gel from letting water into the laminate and resulting in blisters.

Gel coat is not "porous" but rather varying mixtures of gel coat (and, by the way, epoxy and vinylester too) can have different levels of *permeability* permitting moisture to pass through them. Generally gelcoat is formulated to be very impermeable.

From a practical perspective, no boat resin of any type is permeable enough that the water passing through is a problem unless other factors are involved.

Generally the reason blisters form isn't permeability of the gelcoat or poly, it's due to voids in the hull providing spots for the moisture to collect. See the following for a good explanation:

http://www.yachtsurvey.com/BlisterRepairFail.htm

Blisters are caused in the laminate when uncured resin gets wet. The way to prevent this is by using vynilester resin or barrier coat and bottom paint.

See the above link regarding blister formation and repairs. The problem is more complex than "uncured resin gets wet".

Since we're not building the boat in the mold and have no control over how the laminate was made, all we really can do is use are best judgement on what is best.

Paint does not blister unless the substrate is contaminated or you trapped solvent or some other error is application. Painted bottoms actually better because they are another layer sealing the gelcoat are better for keeping your boat in the water, but that all is a moot point once you factor in marine growth which will ruin either finish.

Paint can blister if some expandable liquid gets behind it, period. Solvent, water, or otherwise. Generally blisters won't form between the paint and fiberglass after the paint forms a chemical bond with the substrate when it hardens. But the laminate behind the paint can and will blister if there are voids in it. Paint is also not 100% impermeable. Epoxy is less permeable than other paint types, hence the use of epoxy barrier coats. Barrier coats can also effectively seal hairline cracks in gelcoat, providing a much more important type of protection.

Blistering and delamination over time are far more related to the laminate construction of a boat hull than the coating.

Gel coat is hard so it wears better so many prefer it where you walk.

It wears better everywhere, including places you can't walk.

Erik

 

[erikgreen]

Re: Marine Paint Sugestions

One more quick note:

Some high end boats coming from the factory are painted rather than gelcoated.

It's tempting to assume that this means the factory favors paint over gelcoat for reasons of durability, performance, looks, etc. IE, for "price is no object" boats, the factory uses paint.

The thing is, on many high end (performance) boats, paint is the better option not because it wears better but because poly won't stick to epoxy. The vast majority of those painted hull super performance boats have kevlar, carbon, or other exotic reinforcements embedded that give them very high strength and light weight.

Using exotic reinforcements usually means using epoxy resin. Epoxy resins aren't generally easy to use with poly based gelcoat. Hence other coating systems are used.

Erik

 

[ondarvr]

Re: Marine Paint Sugestions

Lets put it this way, I get gel coat at no cost and I still buy paint.

There is no perfect product to refinish a boat with, they all have their shortcomings.

I don't see any reason to use gel coat unless you want that original gel coat look, because it does look different than paint. If the boat is in the water for long periods of time, then it should have bottom paint on it, so the gel coat will never see the light of day, meaning the original old ugly stuff that's below the water line will be just fine. If its trailer'd then it won't be in the water for long periods, so good paint will work. Good paints hold their gloss and color much better than gel coat will and they're easier to clean.

Its faster easier and cheaper to paint than re-gel coat, and I hate sanding gel coat, so I use good paint and prep it well.

On large yachts paint is considered an upgrade.

Auto paints will work fine, but remember you get what you pay for, cheap paint is cheap paint, so it will cost money for a product that holds up well.

For re-gel coating I use 80 grit to prep the surface, its fast, easy, provides a very good surface to bond to and doesn't clog. All the sanding scratches are easily filled by the gel coat and many of the surface imperfections are too, its not as critical as with paint, which will show every defect.

 

[lowkee]

Re: Marine Paint Sugestions

Ayuh,... The part I quoted is what I'm talking about....

The Ignorant boat builders are following build schedules for mold building fiberglass boats,...
While color durability might play into it,... Color Durablity is NOT their primary concern...
Waterproofing,+ getting the hull out of the mold Is...

Many,... yes Many brand new high-end boats come from the factory,... Painted....

Your aguement, Especially the last line, just doesn't hold water,.....

Really,... Squashing Misinformation is just as important as providing Good information....

PVA gets hulls out of the mold, not gelcoat. You could spray straight resin into a mold and still have it pop out. Gelcoat, after all, is simply resin with high pigment (color) content. As noted by others, gelcoat is not waterproof, so claiming gelcoat is for waterproofing is dead wrong, and is exactly why you must wax your glass boat, to fill in the microscopic pores.

You claim all of these mystery manufacturers who paint their boats. Name one glass boat which is only painted and not gelcoated. I can name one hundred which are only gelcoated and not painted. You can spray on some pretty effects with paint, but it darn sure isn't meant to protect anything. At best, it can be used as a sealer in lieu of waxing the gelcoat (aka, barrier coat). Until it scratches off, that is.

You want easy, pretty and delicate, you paint. You want something to be pretty, protective and last 30+ years, you gelcoat.

I'd guess the exact reason only high end boats are painted (OVER gelcoat, might I add) is because you must pay a premium for them to warranty a delicate paint job. I can only guess, though, since you mysteriously didn't state why only high end boats are painted and not all boats. After all, if paint was even remotely superior, why would any builder bother with gelcoat, especially the low end builders? In ten words or less, of course..

 

[SKIBUM1M]

Re: Marine Paint Sugestions

This is a very good discussion as well as informative. For some reason it seems that people have very strong opinions about their choice of gelcoat vs paint. I hope this debate can continue without anyone getting offended because it seems this is brought up often but it turns into a fight and someone bows out. There are a lot of people who don't know which way to go. Usually it seems someone brings it up and they are beat down by the paint people, so they drop it and paint the boat. Oops is the only one I have seen on here go with gelcoat and his seemed to turn out great. I am gelcoating mine for multiple reasons(some gelcoat was worn into the glass, and I want to change color including where you walk) I will document every step and let everyone know how it comes out. I hope I am not making a $400 mistake. The major reason I have heard against gelcoat is that it takes too much time to sand and polish, but I would be doing the same thing to paint only using much finer grit paper. I don't mind the time I will spend sanding as I find working on the boat relaxing.
Please keep up the discussion and don't get offended by the other side.

 

[ondarvr]

Re: Marine Paint Sugestions

Gel coat is used for several reasons in building new FRP parts and one reason is to aid in mold release. Resins tend to bond better to most anything when compared to gel coat and this includes a mold surface, so any mold release works better with gel coat than it will with straight resin. The more difficult de-molding with resin can cause the mold to lose its gloss faster, crack, need more detailing and applications of mold release, so costs go up. Gel coat also is a very good protective surface for a laminate that can easily be applied when compared to post painting items, although in the transportation industry its common to use a grey sanding gel coat on the parts and then paint them later to match as needed.

Even when parts are going to be painted gel coat is used for a few reasons, some were already mentioned, but others are important also.

A laminate will typically have very tiny air pockets in it, these are very difficult to paint over without fisheyes or pitting, glass fibers at the surface can cause problems when painting also. Plus gel coat is an excellent substrate for paint even when primers aren't used.

Good marine gel coats can help prevent blistering, they won't always stop poor quality resins in the laminate from eventually blistering, but they do help. Barrier coats that are very similar to gel coat, only made with a VE resin base can stop all blistering when used behind the gel coat though.

Gel coat is a very good product for coating many, if not most FRP parts, but its not perfect by any means.

Hatteras paints all their boats, Tiger's yacht "PRIVACY" is painted (all boats by this company are painted), as are many other high end yachts. Cost is one of the main reasons more companies don't paint over the gel coat in production.

Gel coat does wear better that many paints, one reason is that paint is typically 3-4 mils thick and gel coat will be 15-25 mils thick on most parts. It also frequently has a lower gloss, so scratches aren't as noticeable in gel coat.

Good paints have many more potential health hazards than a typical gel coat, so it can be far more costly to outfit a shop that will be approved to spray them.

Paints that work great on the bottom may not work that well on the topside and vise versa, so you need to buy products for each use and they may need to be applied differently.

The main reason I recommend paint is because there are so many steps involved in using gel coat and so many more things can go wrong which can?t easily be fixed. And like I said before, I don?t like sanding on gel coat, it gets boring fast.

Either method can produce good results, just pick one you feel good about and go for it.

 

[wrfalpacas]

Re: Marine Paint Sugestions

Bond-o,

Do you use the base+clear system with prism or single stage?

Thanks, Bret

 

[Bondo]

Re: Marine Paint Sugestions

Bond-o,

Do you use the base+clear system with prism or single stage?

Thanks, Bret

Ayuh,... While they do have Basecoat/ Clear coat paints,... I Hate 'em,...
If Dinged, it's almost impossible to repair,+ blend it...

Prism is a 2pt. single stage Industrial/ Fleet paint...
2pt. Urethane, pretty much the Same as the noted Marine coatings...
It comes in 2 cans, you mix the required ratio of each,+ Shoot..
No extra thinning or nothing like that,...

The finish on the Hiliner above is Just as it was shot...
The hull was Preped, Primed,+ Shot with a single topcoat,... (of cousre, sanded between coatings)
Then splashed about a week later...
No finish sanding,.. No polishing, No waxing...

 

[wrfalpacas]

Re: Marine Paint Sugestions

W-O-W sounds awesome! Which primer do you use on aluminum?

 

[Bondo]

Re: Marine Paint Sugestions

Ayuh,... The 1 my paint guy put in the box for me....

I prefer to Not strip aluminum if I can help it...
Sanding smooth,+ repainting does just as well...
Provided the base layer is salvageable of course...

 

[mrdjflores]

Re: Marine Paint Sugestions

lets get this discussion going again....
my question is more on sanding between layers.
i'm using Interlux Pre-Kote and Brightsides...

sanded the entire hull with 80 grit...removing all the old bottom paint
thoroughly washed down the hull
applied 1st coat of primer
lightly sanded with 120 grit
washed hull again
applied last coat of primer

what grit should i use before applying the first coat of color???

what grit should i use between the first coat of color and last coat of color???

should i do any buffing/polishing to the last coat of color?? (Interlux Brightsides)

thanks for any info

 

[edgarop]

Re: Marine Paint Sugestions

i would use industrial imron from dupont it is a 2 part urethane that can be rolled with reducer(flattener) or sprayed. its relatively inexpensive compared to marine crap paints. nason is the low end single stage auto paint that works very well. i have sprayed both with lots of success. imron is much more durable but only comes in generic colors. nason you can choose any color you want metalic or non metalic. though i would highly suggest using a fresh air respirator system or full face orgain vapor mask.