what does gel coat do that paint doesn't?

[boat_beginner]

I am going to show my lack of knowledge about this stuff and ask this question, what does gel coat provide for a boat that paint doesn't? Is it a more durable finish than paint? I'm not specifically talking about re-finishing a boat, but also brand new ones being manufactured. If it is just as durable as paint, now come new boats don't come with paint instead of gel coat? Is it more durable and take more abuse with bumping into objects? Something I have been wondering for a while.

 

[Bumperlt12]

Re: what does gel coat do that paint doesn't?

Not an expert here but think of gelcoat as an epoxy shell more so than a coat of anything.

 

[proshadetree]

Re: what does gel coat do that paint doesn't?

Gelcoat seals the lower levels of glass to keep elements out. Some epoxy coatings will do the same to eliminate the weathering of raw fiberglass. Gelcoat will take a beating better than most paints. Yd or opps will stop by with a better explanation. Some boats are painted from the factory or at least parts of them are.

 

[Woodonglass]

Re: what does gel coat do that paint doesn't?

Boats are made in molds. The molds are totally void free and smooth as a babys behind. Mold is coated with a release agent and then the gelcoat is sprayed or rolled into the mold and then then the glass is layed over the gelcoat in layers. Some mfg's spray the glass in. Wet on Wet application makes them chemically bond to each other. Gel coat is about 2 mils thick and thus much more durable than the typical paint job. This will show you the process.

http://www.youtube.com/watch?v=kjT_z26kFUg

http://www.youtube.com/watch?v=nu23KgQb9bo&feature=fvwrel

 

[oops!]

Re: what does gel coat do that paint doesn't?

gellcoat is intended to be used with any fiberglass reinforced plastic that is a water immersed object.

while paint is a great barrier to protect against the raw look of fiberglass,,,,,,NO PAINT will live up the the abuse that a boat takes.

a boat lives in a hurricane when its working, (imagine your chevy living in a hurricane)
when the boat is tied up at the dock.....it is constantly pounded by the dock and objects in the water.....
kinda like a car in a parking lot with shopping carts thrown at it hard every 2 seconds.

the only time that a boat lives like a car is when its on a trailer.

for this fact, boats needed a far superior product that could stand high impact stress with out chipping or cracking, and could be applied easily with a mirror like finish.....

enter gellcoat.....
a type of fiberglass resin that is less brittle, and when properly applied, totally water impervious, and will hold a finish for 40 or more years.

though its true about some of the latest epoxy based paints being very very good, they still do not stand up to the characteristics of gellcoat.

the product is so versitile.....it can be made into counter tops, (corian) sinks, even shower stalls.
in fact....it has so many applications that the uses for the product are virtually limitless.

 

[Yacht Dr.]

Re: what does gel coat do that paint doesn't?

I am going to show my lack of knowledge about this stuff and ask this question, what does gel coat provide for a boat that paint doesn't? Is it a more durable finish than paint? I'm not specifically talking about re-finishing a boat, but also brand new ones being manufactured. If it is just as durable as paint, now come new boats don't come with paint instead of gel coat? Is it more durable and take more abuse with bumping into objects? Something I have been wondering for a while.

Gelcoat is a poly base resin .. the boat is a poly build laminate form. So the compatibility is the same.

Some Paints are Very durable..but can not be applied in a mold application .. ( Paint on mold..poly glass over paint ..) .. Its just not very compatible in the build process.

Therefor you have Gel as a finished product out of the Mold. Again..some may prep and Spray Imron/Awlgrip/awcraft or etc .. but Not in the Mold..

Boats are made in molds. The molds are totally void free and smooth as a babys behind. Mold is coated with a release agent and then the gelcoat is sprayed or rolled into the mold and then then the glass is layed over the gelcoat in layers. Some mfg's spray the glass in. Wet on Wet application makes them chemically bond to each other. Gel coat is about 2 mils thick and thus much more durable than the typical paint job. This will show you the process.

http://www.youtube.com/watch?v=kjT_z26kFUg

http://www.youtube.com/watch?v=nu23KgQb9bo&feature=fvwrel

Gel is sprayed Much more then 2 mils .. I think Woody was thinking of Paint on the 2 mil thingy..

Gel is more like 20-30 mil depending on the mold and application..

gellcoat is intended to be used with any fiberglass reinforced plastic that is a water immersed object.

while paint is a great barrier to protect against the raw look of fiberglass,,,,,,NO PAINT will live up the the abuse that a boat takes.

a boat lives in a hurricane when its working, (imagine your chevy living in a hurricane)
when the boat is tied up at the dock.....it is constantly pounded by the dock and objects in the water.....
kinda like a car in a parking lot with shopping carts thrown at it hard every 2 seconds.

the only time that a boat lives like a car is when its on a trailer.

for this fact, boats needed a far superior product that could stand high impact stress with out chipping or cracking, and could be applied easily with a mirror like finish.....

enter gellcoat.....
a type of fiberglass resin that is less brittle, and when properly applied, totally water impervious, and will hold a finish for 40 or more years.

though its true about some of the latest epoxy based paints being very very good, they still do not stand up to the characteristics of gellcoat.

the product is so versitile.....it can be made into counter tops, (corian) sinks, even shower stalls.
in fact....it has so many applications that the uses for the product are virtually limitless.

Not quite Impervious..but better then the alternative of Primer and Paint ..

Paint is applied to some builds..but its an after thought..

YD.

 

[ShellBack89]

Re: what does gel coat do that paint doesn't?

Wet on Wet application makes them chemically bond to each other.

I hope the OP doesn't mind me asking a quick question on the subject. Wood, you said that it can be applied as a wet on wet application. What if you don't apply wet on wet, do you have to sand first or just rewipe with acetone? Also since it is a poly base resin and fills all voids, when using 1708 does it fill the texture of the mat or again, if wanting a smooth finish do you need to sand?

 

[boat_beginner]

Re: what does gel coat do that paint doesn't?

I appreciate all the info from everyone, and the videos, answered my questions very well.
And I don't mind anyone asking other questions at all, I'll learn from them as well.

 

[oops!]

Re: what does gel coat do that paint doesn't?

Not quite Impervious..

YD.

you know......i hear that all the time......from the epoxy reps, from some of the general public. from other companies.

(im not arguing with you here doc....more of a personal industry rant between friends that work with the stuff )

yes...its not 100% waterproof..........BUT///

if we shot a small casting of gell and glass....lets say a soup bowl. put it in water in a bath tub and put a large rock in it......enough that we really stressed the sides, just to the point of swamp.....

it would take many many years for the casting to even get more than a drop of water past the laminate and gell.

so on a molecular level......no. its not water proof........but in a practical level.....yes...it is totally water proof.

personally, i have always thought that it was the epoxy reps that have sold us that bag of goods. they do have data, but the amount is so small, it would never even be a consideration.

 

[r.j.dawg]

Re: what does gel coat do that paint doesn't?

you know......i hear that all the time......from the epoxy reps, from some of the general public. from other companies.

(im not arguing with you here doc....more of a personal industry rant between friends that work with the stuff )

yes...its not 100% waterproof..........BUT///

if we shot a small casting of gell and glass....lets say a soup bowl. put it in water in a bath tub and put a large rock in it......enough that we really stressed the sides, just to the point of swamp.....

it would take many many years for the casting to even get more than a drop of water past the laminate and gell.

so on a molecular level......no. its not water proof........but in a practical level.....yes...it is totally water proof.

personally, i have always thought that it was the epoxy reps that have sold us that bag of goods. they do have data, but the amount is so small, it would never even be a consideration.

Sorry for the second hijack, and my apologies but how would you explain osmosis? Small pimples or blisters? It would seem to this newbee that gelcoat must absorb some water. Or do I need more education? I'm only asking as last week we were redoing the antifouling on our boat and my helper noticed some "pimples". I thought gelcoat was impervious.

 

[sschefer]

Re: what does gel coat do that paint doesn't?

Osmosis is real but it's not the fault of the gelcoat. A lack of envinromnental controls and too high of a production rate from what I've been told, (like wood say's, easily argued hard to prove). Brunswick is probably the worst at pushing production over the limit. Bayliner anyone.. no thanks.

 

[NSBCraig]

Re: what does gel coat do that paint doesn't?

Gell coat is not water proof. Years and years of use have proven it time and again. No boat would have ever gotten blisters if it was. It's a good cheap finish that is applied when the boat is made and works well.

 

[Yacht Dr.]

Re: what does gel coat do that paint doesn't?

Im Gonna try to answer a few questions here ( good thread )

I hope the OP doesn't mind me asking a quick question on the subject. Wood, you said that it can be applied as a wet on wet application. What if you don't apply wet on wet, do you have to sand first or just rewipe with acetone? Also since it is a poly base resin and fills all voids, when using 1708 does it fill the texture of the mat or again, if wanting a smooth finish do you need to sand?

Yes you need to sand if your resin cured.

* That is a general statement regarding general resin. Sure there are resins and cat rates/cure times that might allow you to do a simple acetone wipe ( or no wipe at all depending ). *

As gel is a poly based ( sometimes VE based ) it will shrink. .. so NO Gel will NOT fill the voids. So before application you will have to sand smooth. It will basically mimic the substrate 'texture' ( unless you dont care about the finish..then just coat it.. I dont like to coat underside with gel. It only hides if you do have a problem in the future ).

I appreciate all the info from everyone, and the videos, answered my questions very well.
And I don't mind anyone asking other questions at all, I'll learn from them as well.

Thank you for opening the door to make this an open Thread .

you know......i hear that all the time......from the epoxy reps, from some of the general public. from other companies.

(im not arguing with you here doc....more of a personal industry rant between friends that work with the stuff )

yes...its not 100% waterproof..........BUT///

if we shot a small casting of gell and glass....lets say a soup bowl. put it in water in a bath tub and put a large rock in it......enough that we really stressed the sides, just to the point of swamp.....

it would take many many years for the casting to even get more than a drop of water past the laminate and gell.

so on a molecular level......no. its not water proof........but in a practical level.....yes...it is totally water proof.

personally, i have always thought that it was the epoxy reps that have sold us that bag of goods. they do have data, but the amount is so small, it would never even be a consideration.

I know ..

Yes Epoxy does have its advantages Below the waterline. For barrier coatings.. ( atmospheric conditions still apply when we are dealing with boats and not cups in a bathtub ) .

Gelcoat can hold its own if properly applied under the waterline ..

Paint ( In general ) will not hold up to the durability VS. GelCoat.

In fact for you Iboaters out there reading this thread..you can look up AwlGrip and their suggestions on application and Maintenance issues for there paint ( AWLGRIP= high end $$ marine paint ).

Even coiled up line in standing water is not good for Longevity of the product..where Gel would be no problems .. just an FYI ..

Sorry for the second hijack, and my apologies but how would you explain osmosis? Small pimples or blisters? It would seem to this newbee that gelcoat must absorb some water. Or do I need more education? I'm only asking as last week we were redoing the antifouling on our boat and my helper noticed some "pimples". I thought gelcoat was impervious.

I think that the mix in the initial build would cause a number of effects from the resin. Osmosis would consider the affects/effects of water. You hear about Osmotic blisters..I think it because a failure in the build process.

Properly applied gel and resin to a boat build will not be subject to Osmosis damage on the bottom ( or deck ).

Research Glycol from Poly resin. Yes uncured and improper application of poly resins could break down leaving blisters and other delam problems..

Osmosis is real but it's not the fault of the gelcoat. A lack of envinromnental controls and too high of a production rate from what I've been told, (like wood say's, easily argued hard to prove). Brunswick is probably the worst at pushing production over the limit. Bayliner anyone.. no thanks.

Actually..it can be the fault of the gel application ..

Brunswick is not Bayliner..its Much much bigger..I dont think you should generalize Brunswick across the board. I have seen some Bliners that would rival some higher up builds. Just depends on who and when it was built.

Gell coat is not water proof. Years and years of use have proven it time and again. No boat would have ever gotten blisters if it was. It's a good cheap finish that is applied when the boat is made and works well.

Its Far from cheap mate ..

Its also the ONLY finish product that work in the build structure of the build process of a boat.

Just so we all know.. Gel is not applied Post mold ( meaning its not applied After the glass was applied to the mold ).

Full gel is hard compared to full paint.. but in a build process its really the only thing that they have for a mold application.

Peace..

YD.

 

[sschefer]

Re: what does gel coat do that paint doesn't?

Re-Bayliner, Wood, you're right it was a cheap shot at Bayliner, I'm just not fond of them after having worked on a few of the lower end models.

 

[NSBCraig]

Re: what does gel coat do that paint doesn't?

YD I said cheap not from the cost of buying it, but if you compare it to the actual cost of a proper paint job. Gel is cheaper.

Of course you still need it when building a boat to give you a smooth surface.

Of and come guys Brunswick is way more than just Bayliner, what about Whaler and Cabo?