Why paint instead of gelcoat? - Page 3 - SailNet Community
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post #21 of 111 Old 07-28-2012
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Re: Why paint instead of gelcoat?

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Originally Posted by hellosailor View Post
Conventional "gelcoat" material only sets up and cures in the absence of air. Making it great to apply inside a female mold before frp is laid over it, but impossible to spray like paint, since you'd have to cover it to cure it. There are supposed to be new "gelcoat" materials that will cure in air but at that point maybe price is a problem?
The gelcoat I referred to is not air inhibited and it didn't cost any more than regular gelcoat. It is handled and sprayed just like usual - thinned with acetone etc. You can even use those disposable Preval sprayers for touch up purposes.

I think the problem with it is what has been said in this thread - most people think it's only good when sprayed into a mould before laminating, otherwise it's too much work.

2 part polys have attained the image of being the only way to go and it has become conventional wisdom as a result.

That isn't true.

I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.
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post #22 of 111 Old 07-28-2012
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Quote:
Originally Posted by SloopJonB:902475
Quote:
Originally Posted by hellosailor View Post
Conventional "gelcoat" material only sets up and cures in the absence of air. Making it great to apply inside a female mold before frp is laid over it, but impossible to spray like paint, since you'd have to cover it to cure it. There are supposed to be new "gelcoat" materials that will cure in air but at that point maybe price is a problem?
The gelcoat I referred to is not air inhibited and it didn't cost any more than regular gelcoat. It is handled and sprayed just like usual - thinned with acetone etc. You can even use those disposable Preval sprayers for touch up purposes.

I think the problem with it is what has been said in this thread - most people think it's only good when sprayed into a mould before laminating, otherwise it's too much work.

2 part polys have attained the image of being the only way to go and it has become conventional wisdom as a result.

That isn't true.
All resins polyester or epoxy, including gelcoat will harden in the absence of air or in the presence of air as they are not thinner based coatings, they are an anaerobic chemical reaction that will harden either way.
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post #23 of 111 Old 07-29-2012
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Re: Why paint instead of gelcoat?

Seems to be a little confusion here about resins (which includes gelcoat).

Most gelcoat you see on the shelves of your local marine store include wax, which will rise to the surface after application to create an air barrier that will allow the resin to properly cure. You can get -- and I prefer to use -- gelcoat without wax; the surface of this will not fully cure and makes a chemical bond with the next layer of gelcoat possible. You can then air seal your final coat of gel with PVA or with a film (acetate works well for relatively flat repairs.

Likewise, polyester resins come in two flavors: standard resin (some call it "boatyard resin") which will fully cure; and laminating resin, that even after curing has a "non-cured" surface that will allow a chemical bond with successive applications of resin and eliminates the need to sand/prep between layers.
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post #24 of 111 Old 07-29-2012
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Re: Why paint instead of gelcoat?

The problem with "PAINT', any paint, is that it cannot be immersed for long periods - or it will lift and lose adhesion. For instance, if you are heeled over for a few days and you hull is immersed due to the constant heel, there is a quite good chance that you will 'lose some paint'. Ditto, if you shrink wrap a hull and dont provide proper ventilation or (horrors) have the shrink wrap come in contact with the paint, expect to see lifting and loss of adhesion.
If you carefully look at 'any' paint tech manual, clearly written will be long term immersion or contact with water will result in loss of paint adhesion, etc. etc. etc.

Spraying gelcoat including the final buff-out is easy, once the somewhat steep learning curve is accomplished. Gelcoat can withstand long immersion in water, much longer than 'paint', any paint. Once you paint a hull, you will be constantly painting the hull, especially that part of the hull that 'dips' constantly into the water, or as stated if very long term heeled.

Gelcoat will last 20-25 years if 'maintained', can be 'restored' several times before needing either painting or resprayed with more gelcoat. Paint, especially boat paint, is prone to 'lifting' if in constant or long term contact with WATER (read the boat paint tech manuals !!!!); and you WILL be repainting every 5-10 years thereafter.

I spray both 'paint' (Awlgrip and the Interlux "mega-boat" finishes and "Perfection" etc.) and gel on my boats. No question, I prefer re-spraying gelcoat over 'paint', 'any' paint. Once I learned to spray gel, learned that computers do the best color matching (even white hulls), ... never will 'paint' a boat again - too vulnerable to scratches, to adhesion loss, to waterline 'pimples', etc. etc. etc.

Once you paint a boat, you will be continually and regularly be painting the boat. Gelcoat, or spraying gelcoat, is much much easier and is much much longer lasting.

:-)
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post #25 of 111 Old 07-30-2012
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Re: Why paint instead of gelcoat?

Quote:
Originally Posted by SloopJonB View Post
The gelcoat I referred to is not air inhibited and it didn't cost any more than regular gelcoat. It is handled and sprayed just like usual - thinned with acetone etc. You can even use those disposable Preval sprayers for touch up purposes.

I think the problem with it is what has been said in this thread - most people think it's only good when sprayed into a mould before laminating, otherwise it's too much work.

2 part polys have attained the image of being the only way to go and it has become conventional wisdom as a result.

That isn't true.
What IS true is that it is damn tough for an amateur to get decent results spraying a large surface with gelcoat, there is no way to get acceptable results with rolling/tipping gelcoat without doing a ton of sanding, and many yards will not let you spray gelcoat on site.

It's 5 o'clock somewhere:


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post #26 of 111 Old 07-30-2012
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Re: Why paint instead of gelcoat?

If you read the building a DART thread over at SA which is a great READ on the labor of building a boat

Thye have to be careful spraying gel in the controled enviro of there shop to NOT have it kick in the gun and it seems there really good at it

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post #27 of 111 Old 07-30-2012
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Re: Why paint instead of gelcoat?

Some day you will probably sell your boat.

Considerations:
If today you were buying a boat and had the choice between a 'painted' hull and well sprayed out re-gelcoated hull; and, all other aspects of the two boats were dead on equal .... which would be your choice to buy?

Once you 'paint' a boat, youre eventually going to be 'repainting' that hull for the rest of the days that you own that boat.

Gelcoat 'kicking' in a spray gun ... not a probem. Get a Gel gun with a DISPOSABLE pot. If the gel 'kicks' in the gun, throw the paint pot away and install a new POT.
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post #28 of 111 Old 07-30-2012
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Re: Why paint instead of gelcoat?

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Originally Posted by RichH View Post
Some day you will probably sell your boat.

Considerations:
If today you were buying a boat and had the choice between a 'painted' hull and well sprayed out re-gelcoated hull; and, all other aspects of the two boats were dead on equal .... which would be your choice to buy?
Which is the average amateur DIyer more likely to produce, an acceptable roll and tipped paint finish, or a "well-sprayed out re-gelcoated hull"?

Draw a Venn diagram, with one circle being "How many yards are comfortable with amateurs spraying gelcoat on site," a second "How many amateurs have to tools to do the job? " and the third circle "How many amateur DIYers have the ability to do the job well?"

I hypothesize that you will not get the circles to intersect.
Just for giggles, here's a fourth circle- "How many boat owners would be pleased about an amateur spraying gelcoat beside their boat?"

THAT is why paint is popular among the great unwashed.
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It's 5 o'clock somewhere:


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post #29 of 111 Old 07-30-2012
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Re: Why paint instead of gelcoat?

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Originally Posted by bljones View Post
Which is the average amateur DIyer more likely to produce, an acceptable roll and tipped paint finish, or a "well-sprayed out re-gelcoated hull"?

Draw a Venn diagram, with one circle being "How many yards are comfortable with amateurs spraying gelcoat on site," a second "How many amateurs have to tools to do the job? " and the third circle "How many amateur DIYers have the ability to do the job well?"

I hypothesize that you will not get the circles to intersect.
Just for giggles, here's a fourth circle- "How many boat owners would be pleased about an amateur spraying gelcoat beside their boat?"

THAT is why paint is popular among the great unwashed.
None of that matters to Rich's question. If I had the choice when comparing side-by-side and they looked comparable...gelcoat. No doubt.


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post #30 of 111 Old 07-30-2012
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Re: Why paint instead of gelcoat?

Sure it does, Smack, especially in the context of this thread.

It's 5 o'clock somewhere:


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