hi gang, fixing up the ole BLUE RIBBON this winter and one of the chores is some glass work on the keels as well as spraying fresh gelcoat. was wondering if anyone has some products they have used that they would recommend. i know gelcoat is much more labor than just painting but i plan on keeping her for several years. also, if you have done this yourself, any pitfalls to look out for. i have been a paint contractor for 25 years with much experience with glass, auto finish and body work but this is my first rodeo with gelcoat spraying. your horror stories are welcome, a wise man once told me you never stop paying for your education!!

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bill harris
hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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hmmmmm, not good, really hoping someone been down that road. paint is much easier but not nearly as tough. i'll keep searching.

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bill harris
hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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I dont know if only waiting a few hours is going to be enough time to get a response back.

I know for a fact there are about 10,000,000,000 threads on the forums that already have the info you are looking for. Take a look using the search bar.

I did a minor bottom job and ding repairs last spring. It's not impossible to do.

I didn't have any glass work to do fortunately just gelocat. I discovered that the bottoms of one of my hulls was down to the glass and just rebuilt it gelcoat to original levels.

I tired the perval sprayer and had some difficulty with viscosity and soon realized I needed more chemicals to create the right flow mix. So, I tried the foam brush applicator technique and it worked perfectly.

I used a finish gelcoat that didn't require additives like wax for drying or mold release for sealing. I bought straight finish gelcoat from West Marine as it only requires MEKP for proper cure.

I mixed the MEKP and gelcoat by ratio as per the mfr. specs and didn't have a problem. After several touch up spots I realized there was still a lot of work to finish the job. That being sanding and buffing. Since I had to do that anyway regardless of the application I decided to try the foam brush.

I went by a local marina and purchased a small amount of styrene monomer as a thinning medium. It is really the only recommended thinning agent as it has little to no effect on the curing process. Acetone can be used but in very limited quantity as it can cause alligator skinning on the finish. The styrene monomer can be added up to a 50/50 ratio. It will make the color more translucent if to much is added.

Anyway, with enough styrene monomer added to make the gelcoat flow and settle the project worked perfectly.

You can mix some gelcoat and styrene monomer without adding the MEKP to get the viscosity you want first. Once you've got the consistency you like add the MEKP to the correct ration of glecoat you used. Styrene Monomer does not effect the ratio of MEKP needed.

Good luck and I hope I helped you some what.

thanks martin for the info, i have done some serious searching on the subject and its amazing how much info is not out there for spraying gel coat(entire hulls). i did find a guy who works for bertram yachts who sounded right on. its a three coat process long on elbow grease. dry film thickness of over 30-35 mils! thank god i'm only doing a 16 foot cat, can't imagine doing a big boat. no wonder there isn't much info or testimonials on this site or others cause its a payne in the arse. i'm taking lots of pics and am going to document this adventure and post my results on this site(good,bad,or ugly) so others can benefit from my triumph or folly!! still haven't settled in on what products to use, but i have some time on my hands and you know what they say about that!! thanks, bill

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bill harris
hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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Your Welcom Bill. From what I've read and heard from some of the marina guys it would seem better off to have it done by someone who owns the proper equipment. Spraying such a large area requires that the gelcoat no set or cure too quickly. The marina I've worked with in the past uses a hopper system that mixes the gelcoat and catalyst as it is sprayed and then coats the project with PVA mold release to properly cure.

Here's a link for general gelcoat application guidelines. This is from the mfr. of the product I used.

http://www.evercoat.com/imgs/pis/GELCOAT.pdf

thank again martin, good info. its starting to look like paint isnt all that bad. if i had some free material and a donor boat to experiment with i'd love to try but gel coat and all the associated chemicals aint cheap. besides, i don't want to screw up the boat i'm sailing. i've used interlux(marine pain) before with success both spray and roll/tip. the launch site has some exposed oyster reefs when the tide is low that sometimes gives us the scratchy/scratchy so i think it may not matter if its gelcoat or paint, its still gonna get it. think i'll take your advise and leave gel coat spraying to the pros! thanks again, bill.

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bill harris
hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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2 part LPU is harder than your gelcoat.

You don't have as much protection though, 5-6 mils usually.

Look into System Three WR-LPU, since your a painter and probably have access to HVLP or hybrid gravity gun.
1.3mm tip, 21 secs on Zahn#2 cup...50% humidity and 65 degrees seems to be ideal temperature.



Dan



edited by: DaC, Dec 26, 2009 - 08:05 PM

shopping paint is much more fun than sprayable gelcoat. system three, awlgrip, interlux, marine enamel, single stadge poly, 2 stadge poly, hybrids, there are many choices. check out SUPERMARINE REVOLUTION TS1000, its the first paint for top and bottom side(fresh water) and doesn't require primer if over glass(etching wash prep). the next question is how much material is used on a two or three coat spray? should i get the gallon or is two quarts enough? i have been searching the forums and teck help and it looks like popeye has done a handful with interlux perfection, he should know exactly what it takes. still must do all the glass repair and fairing so i'm not close to spraying yet. there are some big differences in price between say, interlux and awlgrip. is it worth it? thanks again, bill.

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hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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Awlgrip and Interlux are both great paints.
If your going to paint, go with 2 part LPU. Why go through the hassle of prep just to save a few bucks and get a less durable finish?
Single part is supposed to be easier to work with, but these paints really are very easy to apply AS LONG as you realize that they go on THIN. Many thin coats, not few heavy coats.
Once you get the technique down, you can produce a very glossy, almost factory, finish.
Awlgrip is supposed to be the better paint. Most boat yards in my area use it, and they spray it.
I have seen two boats painted with it, but it was rolled on. I wasn't impressed...maybe you need to spray it to get the excellent results.
Interlux Perfection was recommended to me by an old salt who taught me a thing or two about boat repair.
He used it on boats 10 years ago and their owners still report it looks as good as the day it went on.
People typically say a good 2 part LPU will last 7-10 years, but it's just like the paint on your car. If you take care of it and clean/wax it, it will last many more.

I wouldn't paint the boat without first adding a high build primer to fill imperfections. I use Proline, it's a Sherwin Williams marine product line. I just finished a 30' sailboat and 2 quarts covered a single coat (all you need as most will be sanded off).

If your gelcoat is in good shape and you don't have large repairs showing through, Interlux Perfection will adhere just fine with only a sanding primer underneath. You MUST use 202 solvent to clean first if you want to ensure an excellent bond!

Here's how I do it, YMMV:
Make sure your surface is well faired before beginning. Small imperfections can be filled with the high build primer, but you want the big stuff to be fixed before you get to paint.

1) Wash gelcoat with detergent
2) Wipe down with 202 to remove any wax (oils should have been washed off by step 1, but 202 will get anything you missed there too)
3) Light sanding with 80 grit. Your trying to get a good key for primer to stick to, don't sand hollows into your gelcoat by sanding too much!
4) High build primer will fill any small imperfections in your coat (light surface cracks, small voids, etc). Paint this on with a brush, the brush marks will help you see where you have primer left and need to still sand smooth.
5) Leave the epoxy based high build primer only long enough to where you can sand it off without clogging the sandpaper. If you try to sand too soon, the paper will clog fast. Come back the next day. If you wait too long, the primer will harden enough to where sanding requires more effort. Sand the primer off with 220.
6) 2 coats of primer, not high build. This stuff is thin and will NOT hide big imperfections. By now you will have fixed that with initial fairing and with the high build primer. This primer MUST be fully cured before attempting to paint over it with the paint, or you will ruin the paint job because the primer WILL continue to shrink underneath until it has fully cured. Dry and cure are two different things.

Here's what I will say from personal experience on the primers.

If your gelcoat is in very good shape and smooth, don't bother with the high build. Just remember, every little imperfection will show through the two part paint. Just like painting cars, the prep work is 90% of it.

You may instead use three parts of low build primer knowing you will end up sanding one coat off to fix small imperfections.

The primer will allow you to get a more uniform color finish with fewer coats of paint. So it's your choice, you can use 4 or 5 coats of LPU or do it right and use primer with 3 coats of LPU.

So why would anyone not want to use primer before painting (other than extra cost) ?? Because after the primer you MUST sand :)

7) Once primer has fully cured (read manufacturers directions on this) lightly sand to scuff up. DON'T get your greasy hands on it!

8) Wash with water/detergent and let air dry. Assuming you didn't get any oil on it from your hands, your ready for paint (I personally go over it with 202 again, just to be on the safe side).

9) Roll on with a high quality foam roller (I use 4"). I roll the paint on in an up/down movement, only doing a small section at a time (no more than 1 ft wide if your using a 4" roller). Your wetting the foam and rolling off excess paint in your try, then painting it on with LIGHT pressure. Once you have the paint on the hull, go back over it with VERY, VERY LIGHT pressure again, just to smooth out the paint lines that are left on with the roller.

Your painting from dry to wet. So if you start on your starboard side, from the bow, start painting by rolling up and down and moving towards the rear. Once you paint on that first one foot section, your going to have a few lines where your 4" roller overlapped to get you to 12" wide. That's where you go over it again, VERY, VERY lightly to blend in those lines. Your next section of paint will start 12" away from your wet line, and you'll be moving towards your wet edge, overlapping your wet edge some and blending that in by VERY, VERY lightly rolling over with the roller.

Some people instead choose to take a foam brush (dry) and "tip" the paint, but I find that rolling over it lightly to blend in the lines works just as well and is less work. You can research roll/tip on Google and get plenty of hits on that.

The key is to NOT go back and try to fix something you are not happy with. The paint skins over very quickly and if you go back you are going to mess it up. The key to 2 part LPU is that it flows out very well. If you paint it on and lightly roll away any roller lines, it will flow out and blend itself well...ending up very flat.

Putting on too much will only make it more difficult to get a good paint job as you will end up seeing your lines or brush marks. Lay it on thin, with more coats, and let it flow out on its own.

Interlux says that if you come back within 24 hours on a subsequent coat there is no need to sand. This will save you a LOT of work.

Of course, because your rolling on one coat very day, don't attempt to clean and reuse the roller. The solvents in it will deteriorate the foam quickly anyway. On a typical larger boat I would use a foam roller for each side of the boat...they are cheap enough.

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This is where WL-LPU from System Three comes in.

I haven't painted an entire boat with it yet, but I ordered some samples from them and was also given a quart of their clear and a quart of their white to play with by a guy in my boat yard. He was very unhappy with how it rolled, and I have heard similar things from other people that have tried to roll it.

My interest in it was to spray it, since it's water based.

I boat some sign boards and played around with it using a cheap HVLP spray gun and got excellent results. The HVLP gun was a "mastergrip" gravity fed gun that I got at Costco when I first thought about playing with HVLP. It's actually not that bad a gun, but I am sure a professional painter would not be caught dead with it :) I have since ordered a nice Italian "hybrid" gun, which is a LVLP gravity gun. The paint flows out so well I think I just wasted my money on the nicer gun, but it's lower pressure so I should be able to paint with lower CFM requirements on my compressor (I have to haul it out to the boat yard to do the painting).

I got fantastic results with the WR-LPU, but it took some playing around with it. Your going to get some slight orange peel, unless your an expert and really know what your doing...but that's something that is easy to lightly sand and buff out. What you DON'T want are runs, because that's harder to sand out than a little orange peel.

You need to add enough water to it to allow it time to flow out flat, but not too much water so that you get runs. I found that the above Zahn cup settings and about 65-70 degree weather produced the best results. I shot when the humidity was around 50% or higher, which is anytime there is a storm system moving in (where I live, dry CA).

The great thing about the WR-LPU is that it's easy cleanup (clean your guns out with water), and it produced an result comparable with the beauty of fresh gelcoat.

You can shoot all 4 coats in one day too!

If you want extra shine, add a few layers of their clear coat. I still haven't decided if I will use the clear coat or simply go with the semi-gloss look of their paint.

Again, worth a look at for you. You can spray their primer (water based epoxy), let it cure for a few days and be ready for paint by the weekend.

It was cheaper than the Interlux Perfection I used in the past too...without having to deal with solvents. I will be painting a larger boat with it as soon as I get some spring weather.

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Is the Qwlgrip paint worth the cost when compared to the Interlux paint? Not from what I have seen. I know that in the hands of a capable painter in a boatyard it might produce better results, but I haven't seen great results from your non-professional using roll/tip application. I can't say that it's the paint though, because the paint jobs I have seen have all been dark colors (blue and green) and it's very easy to see flaws with a dark color (in addition to requiring way more coats).

Because I know that a good 4 coats of Perfection will last 10 years in the hot CA sun and still look new with some limited maintenance, I would go with the Interlux myself. Not because it's a better product that Awlgrip (Awlgrip has the reputation for being the Cadillac of LPU), but because I know it works very well and has demonstrated long term durability.

I have heard that you cannot wet sand (some people call color-sanding) Awlgrip, but no experience there.

I will say that if you plan on spraying 2 part LPU, please look into what isocyanates are. The solvent based LPU will expose you to them, and you will probably develop sensitivity to them which leads to asthma. Some people may not show any symptoms, but it's a risk that could end your life (chemically induced asthma) as well as the life of anyone in the general area that breaths in the stuff. Shops that spray Awlgrip have expensive respirators with closed air supply, etc. Why put up with that when you can use a waterborne LPU instead (you still want an organic respirator, but these are less than $50 and are only as harmful as spraying any other paint without proper lung protection). The isocyanates can also enter your blood stream through your eyes or skin, so you need full head production as well as Tyvek suit, gloves, etc. My advice is to roll them (you will get 95% as good of a result) or if your going to spray, use waterborne 2 part LPU.

Shoot me a PM if you have any questions, but I can tell you that it's not rocket science and you just need to play a bit with it to get the technique down :)

Dan

WOW! dan, you could write tech manuals! thanks for the solid info. naturally i'm working from a budget, paint being one component with other considerations(new shrouds, forestay,pigtail,etc.). being a thirty something year old boat i'm not concerned as much with "show quality" finish so the exotic priced pruducts are out. but, at the 40$per qt. range there are some good choices. right now, the ole blue ribbon is two different colored hulls with super seventies vinyl graphics and a handful of repairs so anything will be an improvement!

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hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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coastrat

WOW! dan, you could write tech manuals! thanks for the solid info. naturally i'm working from a budget, paint being one component with other considerations(new shrouds, forestay,pigtail,etc.). being a thirty something year old boat i'm not concerned as much with "show quality" finish so the exotic priced pruducts are out. but, at the 40$per qt. range there are some good choices. right now, the ole blue ribbon is two different colored hulls with super seventies vinyl graphics and a handful of repairs so anything will be an improvement!

Yeah, sorry...I really didn't catch myself rambling there until it was too late :)
Keep in mind that your painting a very small area, even if the paint IS expensive, you don't need much of it.
The Interlux Perfection (I'll stick to what I have experience with, although there are other GREAT products out there I am sure) will cover 535 square ft per gallon, at a dry film thickness of 1.5 mils. Well, you will get about 2 mils per coat of wet film thickness, which turns out to be half when dry...or 1 mil dry film thickness. You need about 3 coats, forget the BS marketing by Interlux and your new coverage becomes 267 sq ft at 3 mils DFT.
Your cat is 16ft long, by less than 2 ft draft. Each hull has two sides, so (16x2)x4=128 sq ft. So you're only going to need 2 quarts of that very expensive paint :)

Your also going to need reducers (thinner) and a cleaner (to remove the oils and wax for proper adhesion). Factor that into your cost too.


Do you know if that odd colored hull is painted, or could it have been a donor hull from another boat in tinted gelcoat? If it's painted, you might just be able to strip it and your back to two hulls of the same color...at which point you might just polish them up well?

The guy who sold me my Solcat used enamel paint on it. It looks good from about 5 feet away. He did a pretty good job of blending it into the gelcoat and managed to not get any overspray on other areas of the boat. It's good enough for a $500 cat if you ask me.

When I am done painting the other boat I have to do in the next few months, if I have sufficient paint left over I may do the beach cat (better than throwing away unused paint as it has a limited shelf life). Otherwise the enamel patch job will stay on it until I get rid of it!

Dan

i hear you, 500$ boat rule applies. both hulls are gelcoat and original(one being donor) so that helps, no stripping. 2 quarts of material and reducers is reasonable leaving budget room fo new rigging!

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bill harris
hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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