need advice on paint, gelcoat, duratec

[SKIBUM1M]

I plan on ordering gelcoat on wednesday to recoat my boat. The reason I plan to gelcoat instead of paint is I plan to change the color from white and tan to yellow and purple. If I paint it I am afraid that any small scratch will go thru to the white. It is a bowrider so walking on the paint will cause it to wear thru pretty quickly as well as on the swim platforms. Paint is only about 3 mils thick where gelcoat is about 20mils. this also alows alot more sanding and buffing in the future.
Alot of people here advise against gelcoating. I have experience spraying automotive paint and I wet sanded and buffed out all the orangepeel on my thunderbird so from what I have read gelcoat shouldnt be much different. I plan on alot of time sanding and buffing after the gelcoat is sprayed. Am I missing anything major? Am I making the wrong choice in gelcoating and if so why?
I have had someone suggest using duratec high gloss additive. Has anyone used it? what are the advantages of it? Does it make that much of a difference? since you mix it 1:1 do it go the same as 2 gallons of gelcoat would if I use 1 gal of gelcoat and 1 gallon of duratec?
Thank you for any advice in advance.

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

Duratec works well to reduce the gel coat and allow it to spray and level better, the problem is... especially at 1:1. is that you will be reducing the water and weather resistance of the gel coat a great deal. Gel coat relies on the pigments for 90% of it?s UV resistance and pigments are very expensive, if the manufactures could reduce the pigment load by just 5% and get the same weathering results they would. By adding 100% Duratec to it, you just reduced the pigment load by 50%...not a good thing. The other issue you run into is that by reducing the gel coat you will no longer be able to get the 20+ mils (for re-gel coating you should apply 30+ mils because you will be sanding off a great deal of it) you were going to rely on for long term wear and tear.

I need to go now, so I can add more later.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

Ondarvr, Thank you for your knowlege. You are the restoration guru here. So I am assuming you suggest using straight gelcoat. I will be using a 2.0 mil tip gun to spray it so what should I thin it with if anything and what percentage?

 

[erikgreen]

Re: need advice on paint, gelcoat, duratec

I'd add something here, but wait for ondarvr's answer, it's gonna be better anyway

Myself I'm thinking about buying one of those cup based gelcoat dump guns sometime, you're supposed to be able to spray without much thinning (if any) in those.

Erik

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

The main reason for using gel coat to refinish a boat is because you want that original gel coat look, if you're not concerned about that, then most of the time paint is a better choice.

The prep work for either one is about the same, the big difference is once you've finished spraying, with paint you're about done, when you finish spraying gel coat the work is just starting.

Depending on the gel coat and type of paint, the gel coat will typically cost less per gallon, but you will need 5X more to do the same job, so the costs add up fast. Then all the sand paper needed to do an entire boat will increase the cost even more, not to mention the many hours of sanding involved.

Quality paint will typically look good longer and is a much easier job to complete than re-gel coating, so think it over before ordering the gel coat.

Approximate gel coat coverage..... 1 gallon will cover 80 sq feet, this is with no waste, so add about 20% to that. You'll need to apply about 30 mils to have 20 mils after sanding.

Check out the Hull extension thread before deciding which way you want to go.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

I have considdered the paint route but I am afraid of it wearing thru where gelcoat should stand up to much more wear due to its thickness. Like I said I have sanded paint and due to being unemployed and my wife being deployed I have all the time in the world to do the sanding and buffing after spraying. My concern is a properly done job and long lasting quality job when I am finished, not ease or price of doing it. I do plan on either painting the contrasting color or possibly using vinyl stickers over the new gelcoat. The main areas I am concerned about wearthru are the floor in the bow area, the swim platforms, and the top edge of the boat from getting in and out of it. If I were to use paint I would use automotive paint and am sure it would look just as good as gelcoat but I dont think it would stand up to being walked on or my kids.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

So if I dont use duratec and using a 20 mil gravity feed gun do I need to thin the gelcoat with acetone or is there something better? What percentage do I thin it if I do?

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

Its best to not thin gel coat at all, the next best thing to do is use a Patchaid type product, they're formulated to be used in gel coats for this purpose with as few negative affects as possible. Small amounts of acetone can be used (not recommended), but acetone can inhibit the cure of gel coat, so it may degrade it slightly if over used.

That spray gun will work, it may be very slow, but will get the job done eventually. A dump gun like eg mentioned works very well with unthinned gel coat, the only issue in using one is they require a large volume (not pressure) of air, so a small compressor will have a tough time keeping up with it.

For spraying more than just a small area a pressure pot is normally used, it will spray a much higher volume so you have fewer issues with the gel coat beginning to gel before the pot is empty, although it still happens frequently.

Most high wear areas like you mentioned will have a non skid surface, so I wouldn't worry too much about the paint wearing through. Plus the high end marine (auto also) quality paints are very tough, so it will be at least a few years, most likely many years, before it would become an issue.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

So if the gel coat does start to set in the gun how do you clean it out? It does have the nonskid surface but is gelcoated over it so I will be coating over that hopefully leaving some roughness. I can get a gravity feed gun for $50 do you know where I can get a dump gun for under $100 and what exactly do they look like? I have a 60 gallon compressor.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

Ok I found a dumpgun for $120 online so maybe that is the best way to go if you think a 60 gallon compressor will run it

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

The size of the holding tank on the compressor helps a little, but its the CFM output that matters, the pump needs to keep up with the usage. Otherwise as soon as the tank runs low you need to stop and wait until it builds pressure again.

Many times if it sets up in the gun you just chuck it out, but sometimes it can be cleaned.


You can get a 2 qrt. pressure pot at Harbor Freight for less than $50.00, they aren't great, but good enough for a project like this.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

but will the pressure pot spray it unthinned? My compressor puts out about 10cfm at 90psi. I can run a sandblaster for about 20 minits before I have to stop and let it catch up.

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

Yes it will spray it unthinned, a little patchaid will help though.


10 CSFM should work, that's bigger than most of the home owner type units.

 

[TheLucille]

Re: need advice on paint, gelcoat, duratec

My understanding was the "dump guns" for gelcoat were used to spray gel coat into molds, where the final surface is set by the mold itself.

My assumption was they don't have anywhere near the atomization/spray pattern required to spray a coat of gelcoat over something as a final finish. Is this wrong? I think you'd need a HVLP gun with a 2.X (2.4?) needle to spray it.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

Thank you for all your knowlege. You have been very helpfull. do you know of a source for patchaid? I will be using F57-2993 from http://www.fiberglasssupply.com/Product_Catalog/Gel_Coats/gel_coats.html It is precolored and only $60 a gallon. Is this a good product?

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

My understanding was the "dump guns" for gelcoat were used to spray gel coat into molds, where the final surface is set by the mold itself.

My assumption was they don't have anywhere near the atomization/spray pattern required to spray a coat of gelcoat over something as a final finish. Is this wrong? I think you'd need a HVLP gun with a 2.X (2.4?) needle to spray it.

Dump guns work OK, it is possible to fine tune a normal spray gun and you may get a better finish with one, but sometimes you can't tell the difference, mainly because gel coat just doesn't flow and level that well compared to paint.

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

Thank you for all your knowlege. You have been very helpfull. do you know of a source for patchaid? I will be using F57-2993 from http://www.fiberglasssupply.com/Product_Catalog/Gel_Coats/gel_coats.html It is precolored and only $60 a gallon. Is this a good product?

Fiberglass Supply should be able to sell you the Patchaid.

That gel coat should work well for you.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

Ondarvr, thanks for the quick help. Today I ordered 5 gallons of gelcoat and hardener. They didnt have patchaid so I will try spraying it streight which sounds like it would be better anyway. I will buy the gun and pva locally on wednesday and the gelcoat will be here thursday. I will be documenting everything in my resto thread.
So untill I have questions when spraying I will leave this thread to die.
Thanks again.

 

[ondarvr]

Re: need advice on paint, gelcoat, duratec

Spectrum Color will have the patchaid if you need some.

 

[SKIBUM1M]

Re: need advice on paint, gelcoat, duratec

Ondarvr, Since I am coating over old gelcoat do I want to apply the new at the full 20 to 24 mil thickness or should I spray it thinner to avoid cracking?