need to gelcoat my boat

[striker]

I am a finisher by trade and have spayed many different laquer and epoxy finishes. I have a 24 ft. robalo and thoughout use it has many scatches and a few gouges. I purchased 5 gal. of waxed gelcoat ,hardner and styrine . I need to know best way to fill ,sand and finish. How many coats are needed? Does the 1st coat have to be thicker?how long do you have before it kicks? can you use the waxed gelcoat on every coat ? will the wax from the 1st coat rise through the next coats without letting cure out and prep suface ,take off wax ?? . Ihave a 2 quart hvlp gun?? Any help will be appriciated !!

[longliner45]

cant believe no one has responded yet,,,I cant help you ,,surly they will,24 ft robalo is a great boat,longliner

[marshmat]

Spraying new gelcoat is kind of a last resort for when the existing is too badly scratched and chipped to be able to use a proper marine paint. Needless to say, I've never done the procedure you're looking for.
Wax is a real nasty problem in gelcoats, as with many resins. Nothing can bond well to the wax. Before painting over a gelcoated surface, it's standard to scrub several times with de-waxing agents; you'd probably be wise to allow for this step (although it might not be necessary in your case, I don't know enough details to say for sure). Depending on hardener and temperature you might have from 30 minutes to three hours of working time, you can either mix a test batch or ask the supplier. Mixing the stuff is a really critical issue- the mixing must be absolutely perfect, so keep mixing the hardener and gelcoat for a good two to three minutes after you think it's thoroughly blended. Even the slightest off-balance hardener/resin ratio in one area will screw up the curing process. Best of luck, and hopefully someone better suited to helping you will respond.

[the1much]

fill small scratches with a light weight filler, then sand everything with 220,and you should be able to spray just one thick coat, if you need 2 coats the easiest way is to spray 2cnd as soon as possible, that should be on the pail of gel. always go by the makers directions. if you try spraying a 2cnd coat a day or so later you'll need to sand between coats, the wax wont matter,,you'll be sanding that off. i havent tried spraying with gel with that kind of gun,, seems to me it wouldnt be good because the gel kicks off pretty soon,you would need to clean your gun after every cup, and clean it fast at that. i use a 'cup" gun,, its like your hvlp, but gravity fed and the cup is a carboard cup"paper" that you throw away afta each use, on your boat you'll probably go through about 5 cups maybe more.

[ondarvr]

Are you sure you want to use gel coat? Respraying a hull with gel coat is not a fun or easy project, especially on a 24 footer. It requires a great deal of sanding after it's sprayed and that means you laying on your back holding a sander, or hand sanding for hours on end. Painting is much easier and can cost much less to do.

You can use waxed gel coat, you just need to make sure you apply the next coat before the first one is tack free, if you don't, then you need to sand the entire surface before appling more, you should be able to do the whole job in one session though. If you want to thin the gel coat, you can add a small amount of styrene, no more than 3 to 5%. As you add styrene you will lessen the water and weathering resistance of the gel coat, so use as little as possible.

It is very important to add the correct amount of catalyst (2%), too little or too much and you may end up with a poor finish that won't last very long.

The surface needs to be sanded with at least 80 grit for a good bond.

Gel coat does not spray like paint, it's much thicker, so it doesn't level and flow very well, this leaves a great deal of orange peel that needs to be sanded down, then buffed and polished.

[28 CIGARETTE]

very simple , what you need to do is sand down with a DA sander /foam backed pad with 220 grit paper. go with the 3m hookit combo , any body shop supply will have this.

1st mistake is getting gel coat with wax in it. you need to buy straight gel. you also need to purchase a product by hawkeye industries called "dura tec" clear additive. you cut the gel coat 50/50 and ad your mek.

the smart way is to spray 1 side at a time , do a tape line at the corners , keel ,and the chine edge on the hullside.you have a decent window to spray ,lay it on , 2 medium wet coats , 1 prefer 3 good medium coats , 2 will do , it will spray almost like acrylic enamel on a cold day.

let it dry overnight , wipe the tape edges at the transom and keel with acetone , tape 1/16" over the previous line from the day before.

repeat procedure. let that dry a day.

next take by hand and sand down the tape lines with 500 paper. i forgot to mention , when you buy your 220 get a roll of 500 .and don't but the cheap stuff, take the DA and sand down the gel coat with 500 with the foam pad. you will want to level off the gel. it will have somewhat of a shine , but by sanding it down you will get a much more level shine.


then , you are going to have to buff , best product is "aqua buff" by hawkeye. there is 1000 and 2000. just get the 1000 and it will polish out those 500 da scratches like you would not belive. best thing to use is a 3m double side wool pad at about 2k rpms. keep a spray bottle of water and mist ,it will help with heat and keep the pad from building up with compound. using a double pad gives the ability to flip the pad ..

good luck , don't let it intimidate you...if youknow how to spray , you can do it , as for this web site , it has not been the most helpfull in getting questions answered.

[ondarvr]

A 50 / 50 blend is not a good idea, dura tech clear is, well, clear. Gel coats rely on the pigment loading to help protect them from UV rays, so you just cut in half the amount of pigment, this can yield a better gloss initially, but worse weathering. In testing I've seen it also makes the gel coat softer and less water resistant, not qualities you want in a hull coating.

It does make it much easier to spray, as it will level and flow very well making it much faster and easier to sand. 80 grit gives a much better and more reliable surface for the gel coat to bond to, not that it will fall of with 220, but 80 on under water areas is better.

[fiberglass jack]

Go with the info that 28 gave u, its what i do every day. I use a devilbliss plus with a 1.3 tip and the gel will go through with no problems just thin with 10% acetone, a light coat followed with 2 wet, i also add some wax addative to my mix, my mix is 50 gel 40 duratec 10% acetone with 2% airdry wax added, and 2% hardner. after the third coat i clean my gun out and give a fog coat of acetone, this will level out the gel just a quick fog will do, I have sprayed gel that look real smooth just a quick cut with 600 paper and buff with aqua buff, the trick i find is with the gun everyone uses a cheap throw aways , the devilbliss plus is able to push the gel through and atomise, only down fall is they cost around $450, if your using your good guns just keep a cup or 2 of gun wash and flush your gun between fills also you will want to back flush the gun, the gel will stick just fine with 220, never had a problem yet, try and remove a part from a mould that hasnst been wax and sanded with 1000 grit it ant coming off

[28 CIGARETTE]

being down south , i just go 50/50 like the instructions say and 3 good medium wet coats , i know it's a clear additive and cuts the thickness of the gel. but , i think he will be just fine. 80 grit will also work too..i just find for a "refinish" 220 works well for me..i use a 2.2 air cap with good pressure. really puts the material out..

[ondarvr]

As a gel coat supplier we do not recommend this type of reduction for gel coat, especially when it's used below the water line. While it does work to make life easier for the person doing the job, you are reducing the ability of the gel coat to do what it was designed and formulated to do. Gel coats are not formulated to be used in post coat type applications, all of the research goes into in mold applications, they just happen to work most of time. We know that people use our products in many ways that may not be the best for long term results by adding large amounts solvents and other products not made by us. If these addatives were improving the performance of the gel coat they would already be in the formula.

In testing we see huge differences in weathering when we cut pigment loadings by much less than 50%, if we could cut 10% of the pigment out and get the same results we would do it to lower the cost to our customers.

Resin and gel coat suppliers actually do a very poor job of getting information on how these products are designed and formulated to be used into the hands of people on the shop floor, resulting in people coming up with methods of using them that seem to work very well, but sort of undermine what they actually want to do.

I will add that I was a fabricator for many years and during some parts of the year my crew and I were using gel coat to post coat the equivalant of three 40 foot boats a week. So I do have 30+ years of using these products in the field in this way.

[28 CIGARETTE]

teach me something.. then why did hawkeye products come up with the gloss/flow additive?

the dura tec vinyl ester primer is the bomb when it comes to fill , fair , build in repairs and restorations.

in doing small repairs , you could use straight get coat with wax and have the ability to spray and get enough flow so the gel didn't just puddle up in layers ...

painting is a good option...but it scatches and chips way more than gel will.

as for gel coat or any other coating , without proper care anything will fade , chalk , dye out etc..

i know i have seen boats that are only 2 or 3 years old and gelcoat is chalked ,low gloss from lack of care..

so , are you saying that gel is really only designed for new construction?

are you saying that by using this method that the gel will break down ?

a post or 2 before me said that he used acetone to cut, now i don't do that, but we all have to find ways to get products to work for us relative to our area of the globe we live/work on.

not everyone has a building that is 77 degrees with 50% humidity .

so , from a supplier point ,what is the recommended way? or are you saying that you can not do a complete re-gel over existing gel coat surface?


i am always receptive to learn something .....

[ondarvr]

I know the owner of Hawkeye, he's a great guy.
They developed it to do exactly what you are using it for, but that doesn't mean it works well for every type of application, but it is fast and easy. The harsher the environment it will be in, the more the need for it to be virgin gel coat, not mixed with other things. On an indoor item, or a part not exposed to much water or sunlight, you may never notice any problem, on a boat kept outside in the water in Florida, problems may show up in the first year.

There are gel coats that weather very well, the problem is they cost more, sometimes it's a lot more, and boat builders don't want to pay the higher price.

It also depends on how well it was applied. When applied well, even some of the lower cost products hold up fairly good, but even the high end products don't perform well when not used as recommended.

Yes, gel coat is designed for in mold use only, it does happen to work when applied like paint most of the time, but little or no lab time is used to develop those properties.

Gotta go, will continue later.

[28 CIGARETTE]

good info.... i also see vinylester gel coat 585 by LBI inc out of CT. for 299.50 for 5 gallons.

i do not see vinyl ester gel coats on mini crafts website...just isothalic.

what is your knowlage/feeling on the vinyl ester products , to me , if it's more durable, it's worth it. i also see the cost factor to a manufacture as the costs of building boats is really going through the roof...

i understand your viewpoint on the location ,florida is always warm and harsh on everything.

http://www.lbifiberglass.com/lbiprod...l#anchor537266

[the1much]

if everyone gonna get technical,,its waY easier to say,,do whatever the maker of the product says, no matter what, that way if anything cost you extra from it not working right, you call the rep. and send him the bill. i have a few refund and over-cost bills that have been paid that way

[Tynaje]

28, stand your ground, you are on the right track. I have been pushing gelcoat recoating for 4 years now. I dont pride myself on being a styrenated expert nor do I even like being around the products, I prefer high end advanced composite construction. HOWEVER, I think there are a couple of things that are being overlooked here. And I also have 30 + years of hands on experience, but I havent stopped learning yet.
Why and when are gelcoats used in new construction?
What are the diffenrences in profiles between paint and gelcoat?

I will try to make it short and simple.
Gelcoat's profile runs and hides from air, so when used in a mold, all the shine properties are against the mold surface.
Urethane and other paints' properties seek air. I won't go into Acrylics etc.
SO, when buffed, the gelcoat loses its propeties as the materials are ground away by the process, chasing the shine is a lost cause in older decayed gelcoats. Its why you can spend hours and days with no results on older boats.
Urethane is basically the same, buffing usually kills those profiles in time, yet I had extended Awlgrip on our own boat for years before recoating in Acrylic Urethane for repair reasons. The profile blows away classic Awlgrip IMHO.
So, accepting this, as I do, we touch on the why NOT spray gelcoat as a finish? Or why isnt straight uncut gelcoat sprayed as a finish?
If we just thin the stuff and apply it, then cover with PVA as was the standard for repairing patches, what have we got? We have created a situation that exists when it is applied to a mold surface, all the profile is agains the substrate. Chasing that shine yields little to no mill thickness and constant burn throughs.
So, why do we add Crystal Clear Duratec? It's simple, it seems to suspend the profile in the entire mill thickness, thus making buff back a breeze. I think there are other benefits to it, but I dont think I want to opine too much. What I have noticed is scatches dont show as much due to the clear, I have heard that the clear makes the gelcoat too opaque, dont agree. I have heard it all, so I just experimented and listened to others. Then came to the conclusion the Duratec method lasts longer and yields better buff back.
I think it is a great method, sand with 80 grit, NO primers, I usually pile the crud on and block the first application, which tends to lightly fair without long boarding. Then I do a final application, again piling it on. I sand to 1500 grit and buff then seal it. Repairs are easy, I even make a putty using the MIXED gelcoat, works great, but cannot be buffed, the filler tends to burn and darken when buffed.
I use a gravity feed primer gun and completely tear the gun down and clean after two cup fulls, go to 3 cups and trouble starts. Duratec's only bad issue is it is a time bomb when properly kicked. Losing the gun mid stream is no good.
For the DIY owners, it's the way to go. If it lasts 10 years at the same cost to apply and holds it shine that entire time, then........?



http://s119.photobucket.com/albums/o.../Bertram%2025/
Acrylic Urethane, color sanded and buffed.