Boat Builder Central - Builder Forums

Some tips on the using the System 3 LPU paints and primers:

-Sanding the primer with more than 100 grit can lessen the paints ability to adhere. Stick to 100 or less.

-You will get less coverage from colors like yellow and red. Its takes more coats to get an even tint.

-Let the primer cure for at least a few days before painting

-Follow the directions as far as when to apply multiple coats

System Three paints give a very hard finish that is extremely durable. They are also the most easy for an amateur to get right, we highly recommend them.

Here is a video clip of how we roll and tip S3 paint...

http://www.youtube.com/watch?v=LTVVjzbA72U

Sanding the primer with more than 100 grit can lessen the paints ability to adhere. Stick to 100 or less.

For the abrasively challenged among us...does 100 or less mean a higher number or a lower number (80 grit is lower, 180 is higher)?

Thanks!

100 or lower - use 100, 60, or 36

Joel,

How in the world could you ever achieve a good finish if you have to stop at 100 grit? Does this mean work boat finish only from system 3? I know I worked some areas down to 400 grit before painting. Is this more an issue with not cleaning the sanded surface well after sanding?

I just pulled my "bateau.com" stickers off the hull after two years because some black mold started under the edge of the decals. They pulled off fine and no paint came with it. Did I just get lucky?

Just wondering.

JimW wrote: Did I just get lucky?

Just wondering.

I must be a CYA thing. I know a lot of folks have sanded the primer to the point that it shines, and had no problems with the paint sticking. But we have also had guys who’s paint peeled off. When it peeled off, it did so in sheets. I went to S3 with the issue and they said because it came off in sheets - it was obviously an issue with adhesion. It was either a contaminated surface (grease, blush, and something else), or the primer was too smooth and there was not enough “gripâ€

Yep, I had a few spots on my sole where I sweated on it and just wiped it up and didn't "clean" it. Those small circles peeled within 3 months. But the rest of the boat is still "tight" after three years.

It's not a CYA thing--its pretty standard paint prep. You do the same thing with cars.

If fact if you do a spot repair on an automobile, the standard instruction is to scuff the surface to improve adhesion.

ditto home painting--you only take sheetrock "mud" down to about 80 grit.

REading Shine's note, you can sand the topcoat to your heart's content, because there's no adhesion issue.

The issue is because System Three paints use a water carrier, rather than the carcinogenic carriers in many other paints. As water molecules are relatively large, you need a better key for the paint to bond properly.

This shouldn't mean a poor finish though - you just get it faired correctly then give it a final key with 100.

What is a standard paint prep...?

I had just finished wet sanding and buffing my system three paint,it looked incredible.The next day I noticed a small blister on the bow, I picked at it and low and behold every bit of paint peeled off the boat. The boat was only sanded to 100 grit (per joels warning)and wiped clean with acetone many times before coating.I had one small spot near the bow where I had sanded through the primer(wr 155) and oddly enough thats the only place the paint stuck.I'm glad others have had good results with this product, personally I will never use it again. must have been a bad batch.

brian in cc wrote:.....I had one small spot near the bow where I had sanded through the primer(wr 155) and oddly enough thats the only place the paint stuck.I'm glad others have had good results with this product, personally I will never use it again. must have been a bad batch.

Hey Brian,
What primer did you use...? and please explain what you mean by wet sanding...are you adding water while sanding...? or sanding while the epoxy/primer/paint is still wet... ....I am a little spooked by your experience...can we see some picture...?

I hope things work out for you....good luck..

I don't think Joel or I recommended to wipe with acetone. And whatever we say, what counts is what the paint manufacturer recommends and that's wiping with a damp cloth, with water. I am afraid too much acetone was used.
I use that paint system since it came out: brushing, rolling, spraying and it always bonded perfectly well and gives a very hard finish.
We have an FL12 in the warehouse that has been abused and the paint stands up very well.
I don't think there can be something like a bad batch, those paints are manufactured under the control of a chemist (John Bartlett) and the quality is consistent. This is almost certainly an application problem. I don't know what the problem is but if that paint works for us and many others, I wouldn't blame the paint.
Did you mix the activator with the paint?

I thought it might help if I gave a rundown of my pre-spray procedure. sand primer to 100 grit. Blew off dust. Wiped down with acetone to remove oils from hands. Boat sat overnight. I sanded a few spots I missed the night before. Wiped down with acetone. Wiped down with water ,waited to dry and then vacumed and sprayed. The paint went on great with very little orange peel. I waited about three days and began wet sanding with 600 grit all the way through 1500 grit and buffed per manufactures directions.I could not have been happier the paint buffed to a mirror finish. I might add that I sprayed a friends boat with the system three paint using the same procedure and had no problems. I'm glad the paint came off the way it did (in big sheets) it made it much easier to remove.

Could the problem be that the primer is not given long enough to totally cure? All of that water used for thinning the primer has to be given time to out gas. Ditto with the paint.

Paul

I dont think that was the problem. The primer was on the boat 8 days before I sprayed the paint,maybe I sanded and buffed too soon. I honestly don't know what the problem was. I didn't mean to talk down on the product ,I was just more than a little upset when all my beautiful paint peeled off my boat. It probably was something I did, I just don't know what.

Acetone can be contaminated with other substances; it is often reclaimed. I would suspect that either some acetone vapour was trapped beneath your paint or that the acetone left something nasty behind when it evapourated.

In my opinion if a paint is water based, I would clean with water before applying and if solvent based, use a similar solvent.

What prep does the manufacturer recommend ???

The manufacturer recommends water or rubbing alcahol.I'm sure now that the acetone was the problem, I dont know what else it could have been. My friends boat turned out fine and I used acetone on it also. Like you said maybe the acetone left something behind,but here's a question,Why did the paint stick to the spot where I had sanded through the primer. It also got wiped down with the same acetone. It doesn,t really matter now as I've just primed again with awl-grip 545 primer.I would just hate to see it happen to any one else.

I understand; I didn't mean to insinuate that you were questioning the quality of the product. I feel for you. It's a tremendous amount of work to get to the point of applying paint. It's tough to try to second guess from here what might have caused the problem. I hope someone comes up with an idea that sheds light on it for you.

Paul

I understand; I didn't mean to insinuate that you were questioning the quality of the product. I feel for you. It's a tremendous amount of work to get to the point of applying paint. It's tough to try to second guess from here what might have caused the problem. I hope someone comes up with an idea that sheds light on it for you.

Paul

I have an idea about this. WEST publications make a big issue that adhesion problems are always from contamination and that rags can be a source. Specifically since fabric softener is known to impede adhesion and can be found in cloth rags. They strongly and repeatedly recommend wiping only with paper towels. So - Brian, did you wipe with cloth rags? Also, did you happen to note whether the wash water ran off in sheets rather than beading? One last, compressed air can contain oil.
What a nightmare for you, Brian!

yes it was a nightmare,but it's all good now I sprayed with awl grip and it looks like a million bucks.Thanks to the board for all of the support during this calamity.

As I just posted on another thread. You can go to www.systemthree.com and register for free. They have a desciption and application guide the primer and paint you can download for free. It says to sand the epoxy to 150-grit and wipe with a damp or alcohol-wetted rag prior to primer. After primer dries start with 100-120 grit and progress through 220-320 grit in preparation for painting.

Shine wrote:Some tips on the using the System 3 LPU paints and primers:

-Let the primer cure for at least a few days before painting

Any idea on how long to let the final topcoats cure prior to putting the boat on a trailer?

My D15 is pretty light and i am trying to push a schedule to launch and i need to flip for the last time onto the trailer and finish the rigging of the boat while the topcoat is curing the recommended 2 weeks prior to putting in the water. Just do not want to have any indentations from the bunks in paint that might be soft???

Look on the container of the solvent used to wipe down the primer. If it says reclaimed or recycled don't use it. Get your acetone or lacquer thinner at a paint and body supply and it will be highest quality.

Robertk

Hi All,

I'm trying to plan ahead for painting my GV11 while I'm finishing up the fairing, etc. These paint discussions about compatibility are confusing me a bit. When I looked at the spec for two part linear polyurethane (LPU) I see it is polyester based. But when I was reading System Three's "Epoxy Book" it says:

Caution must be observed when using epoxy resins along with
polyester resins . Observe the general rule that epoxy resins may
be applied over cured polyesters that have been dewaxed and
well sanded but polyesters should never be used over cured epoxy
resins. Unreacted amine in the epoxy inhibits the peroxide catalyst
in the polyester causing an incomplete cure at the interface.
Sanding does not get rid of unreacted amine. The result is a poor
bond even though the surface appears cured. Debonding will be
the inevitable result.

What am I missing? Are there different bases (polyester and non-polyester) LPU? Or should I just go with oil-based exterior floor paint as Evan suggested?

Thanks!!!

Sandy

Polyester resin is used mainly in commercial boat building occasionally in boat building and in car repairs(Bondo). If you have used epoxy in your build you do not have a problem. Only if you have used polyester resin then not let it cure properly and then applied epoxy resin over does this apply.

The 2 part LPU paint is a different animal and is polyurethane not polyester. So it reacts very differently to coating your boat hull in coating it.

Hope this helps.

Tom

Just read about the recommendation to wipe down ONLY with paper towels. My (limited) experience with paper towels is that when I wipe with them, they seem to leave "lint" on the surface. Also, I believe that some brands of towels for shop use are chemically treated for one reason or another, so is this another problem? Is there a recommendation for a particular brand of towels that doesn't cause lint or other issues?

Wouldn't the fabric softener issue be solved by washing and drying the rags without fabric softener before you use them? If you use microfiber cloths, they say NOT to use fabric softener when washing or drying them.

I wipe down the sanded (120 and sometimes to 220) and masked fully cured primer with 70% iso alcohol on plain white paper towels. Then a light wipe with dry paper towel. At this point there is the slight *lint* problem. I then wash my hands thoroughly with Dawn detergent and rinse them very thoroughly, and dry thoroughly with plain white paper towel, leaving them essentially oil free. Then I immediately go out to the prepped surface and very lightly swipe the prepped areas within five minutes. My hands can feel lint and swipe it away. After five minutes, if I'm not done, I wash and dry my hands again, same procedure, since after 5 minutes, you might begin getting oil on the skin again. This finally swiping of lint is a very light touch, if you want to think of it this way, *not enough to leave a fingerprint, but enough to sense and swipe lint into one corner to suck up with the vacuum*. I haven't had any paint peel after a year over most of the boat, and after four years on some sections.

I'm watching the sections I sanded to 220. I found 100 grit left grooves that needed MANY coats to fill, too many. Now I try to stick with 120-180 and no finer or coarser for the final prep. Isopropyl Alcohol is the solvent specified for thinning, so it is the best for final wipe down. A caution though... they specify 70% cut with 50% water. I used 91% straight on some small areas to remove overspray and tape bleeding, and using that strength too agressively definitely softens the finish of even cured LPU, even with crosslinker!

Regarding the earlier posts of the whole finish coming off in sheets, except at where the primer was sanded through.... Acetone or its impurities might get trapped or have a light bonding with sanded primer exposed pigment material, but not in sanded straight epoxy. This might explain why some paint adhered where the primer was sanded through to the epoxy seal coat beneath. Bottom line, acetone prep for straight epoxy but never for primer or LPU. I did some acetone wipes before the primer application, but followed them up with alcohol wipes and then filtered water wipes. I've never had a problem with primer adhesion. I'd also wait at least a week before attempting to wetsand or buff LPU, since buffing can generate heat. I'd want that LPU totally totally cured before buffing. Hope that helps.

About rags... rags can be purchased in bulk. But such rags have the question surrounding them of whether or not they were exposed to fabric softener before you bought them. And then, how much do you need to rewash them to get the fabric softener *out*? Brand new cotton Tshirts, washed several times without fabric softener, will be nearly lint free, but not entirely. On small home projects, I still think the final hand wipe to be effective and safe, as long as you don't have incredibly oilly hands (some people do).

One last thing... washing your hands with Dawn is not a good daily thing to do. It really dries out the skin as it cuts oils very well, and this would not have good long term consequences for skin health. I do not prep and paint boats daily using the method I described, so I'm not washing my hands every day with straight Dawn detergent all day long. Skin makes those natural oils for good reason, but that reason is not so they can be smeared all over your LPU prep.

Paper coffee filters are pretty much lint free, readily available, and cheap. I still follow up using a tack cloth and very lightly wiping the surface.

I wash my microfiber towels in liquid, fragrance & additive free, laundry detergent. The towels are only washed with other microfiber towels. No fabric softener - you don't know what chemicals may get leached out of the towel and deposited on a surface to be painted. Worst case is a solvent wipe down with a contaminated towel will leave trace compounds that could cause fish-eyes & other paint defects.

As for washing microfiber towels only with similar towels, I came across these guidelines in some popular car detailing forums. They're meant to prevent the towels from getting fibers caught in them that can scratch the mirror finish on cars. One test of your detailing towels is to rub them vigorously on the surface of a compact disk. If it scratches the disk, it will scratch your paint. Some of the polyester threads used to stitch the edges of cheaper microfiber towels will leave scratches on a glossy paint surface.

However, in my opinion a lot of this is overkill for a boat, unless you're looking for a competition level finish. The fish won't know the difference.

I'm building a GF-16 and I'm at the point of deciding on a paint.....After reading 3 pages of posts, it looks like rocket science to paint a boat. I've tried to investigate all the popular paints and the more you read, the more it is confusing of what is the right choice. I'm not looking to put this in a boat show, but would like a paint job that will hold its gloss and not peel. Most paints say "not for use below the waterline". Well, since the boat will be trailered and only in the saltwater for approx 8 hours or so, does this apply? I have done a lot of painting(not boats) and common sense prevails in most situations. I know the surface must be clean, dry, contaminent free, have the correct weather conditions to apply and have a rough surface for the primer to stick. A primer does two things only, it is a binder for the paint and also a filler, period.
System Three is the only paint that is water based (that I'm aware of) but all of the posts I've read seems to have been a sprayed application. I want to brush only. Can the System Three clear gloss be used on the exterior of the hull only and 1 or 2 coats? How about using a marine enamel on the interior of hull that be touched up easily and a lot less costly?
I'm sorry, it appears just like a lot of overkill with some of these suggestions. I , however am certainly aware of correctly prepping the surface. Common sense approaches comments would be appreciated. Also, any comments on other brands of paints that you have experience with.
Thanks
Bill

TomW wrote: The 2 part LPU paint is a different animal and is polyurethane not polyester.

Correct. Polyurethane is not polyester.

Acetone leaves a residue on evaporation whether it is reclaimed or not. I tried using it for prep once and my great nose still smelled it on the surface the next day, so I read up on this subject. There are actually some chemicals that remove acetone residue, isopropyl alcohol is one (IPA), but water is not one of them. I believe the cleaning regimen is acetone, IPA, then water, but I would NEVER use acetone with water based paints or any for that matter.

The likely reason the paint 'stuck' on the area where the primer was sanded through is that the 'key' as one person mentioned was strong enough to overcome the residual acetone, or the bond between the primer and first coat wasn't cured properly.

I read another forum where the author suggests applying epoxy over the wr155 as a barrier coat. Does anyone know why this would be needed and what the benefit would be? I found it interesting because that was where the paint stuck right?

Sorry if this is a dead thread that I've brought back to life, but a couple issues needed some clarity and the barrier coat is a curious notion I know nothing about...

One other point the LPU topcoat says it will blister if immersed or used below waterline. I'm guessing if any water didn't cure out of a first coat of topcoat or the primer before recoat, or if the boat was too wet (humid) when painted, peeling could have resulted as well (low humidity is bad, too, because paint won't flow out). The instructions suggest to spray subsequent coats within 8 hours, but I'd be nervous about hitting it too fast. Its a guess, but the prior coats need to cure enough for the next coat, etc.

A barrier coat such a wr155 is only needed if painting over polyetester or other non-epoxy coating. Barrier coats provide the same water proof coating that epoxy does. Using a hi-build primer such as System 3's SilverTip primer prevents any need for a barrier coat in our building process. It can also be used on Gelcoat that has been roughened up.

Acetone is a fine cleaner on epoxy to epoxy bonds but when it comes to painting you want to use what the paint tells you to use. This can be anything from water to specialty chemicals made by the paint company. Do not short on this step. Acetone should also be used in a two step wipe on, wipe off system, damp towel in one hand, dry towel in the other.

All LPU paints are 2 part polyurethane paints, whether System3, Sterling, Awlgrip, or Interlux. They can all withstand a bit of being summersed in water but none are made to be used for extended periods below the waterline. Depending on the paint 1-2 weeks is as much as any of them can endure. If the paint says to spray within 8 hrs do so otherwise the bond will not be as strong between coats. Some paints have a thumb test at which if no paint comes off on your thumb when pressed to it you can recoat. These are totally new paints and have totally different chemistry's from what we have been used to in the past. They are designed to go on easily and last a long time with a high sheen and a high hard long lasting finish.

Hello Tom,

I don't want to sabotage the thread, but the thread did leave a lot open ended. Given the choice would you use a water based paint or something else in painting your boat? Thanks for the reply in advance. I'll give you last word.

Of the LPU's, the S3 topcoat sold here is the only one I know of that is water based. I'll be honest and say I am not going to use it. It doesn't have the shine of the other LPU's and people have had a harder time putting it on smoothly. A lot of guys have gone with the Sterling sold here. They did not have the color I wanted so I am going with a newer brand called AlexSeal it is from a German company and sold by Hamilton Supplies. Chemistry is similar to Sterling/Awlgrip. Some of the guys have used the Interlux Perfection and gotten a nice finish. One of the guys uses Awlgrip as he likes it.

So pick your poison and pick your color and go with it. There is a Sterling application guide here on the site. Interlux also has good info on there website. I would stick with the S3 Sivertip epoxy primer it works well with all the paints.

Tom

I am choosing System 3's product from start to finish for some of the reasons others avoid it. Being water based, it is a much safer product to apply in my situation (low ventilation area) as it sheds minimal VOC's. It is water reducible, which makes it more eco-friendly for cleanup, requires no petroleates to manage brushes, and won't contaminate my ground water. Another plus is it is not only a domestically produced product, it is actually a Washington based product, meaning it is buying locally.

I have used the WR-155 and the WR Yacht Primer now, and both products were great. Keep an eye on the web page, I will document the process and any failings I run into.

E

I haven't tried roll and tipping a large area with S3 yet, but I may do that with the seat tops. A month yet before that though.

I am building a v12 dinghy. When I buy paint and primer about how much do you think I will need, would one gallon of each be too much? Do I need fairing compound also?

OK one more question for my v12 dinghy, I need fairing compound for fiber glass joints, Right?
and then Primer,?
and then paint, is that bottom or top coat
and then a finish coat?
that is alot..

after construction is completed, then you fair.
when fairing is done, I like a seal coat or two of epoxy, but with epoxy based primer, that clear epoxy seal coat over the fairing is not as important.
after the seal coat or two of epoxy, over the fairing, then you prime.

after the primer comes the paint, sometimes called topcoat.
and optionally, over the topcoat, you can put on a layer or two of clear, to bring a gloss that helps protect.


some seal the fairing with epoxy, and skip the primer altogether, going right to topcoat. I think priming is a wise thing to do, a primer that is compatible to your topcoat system.

Ready to paint my HC 16 first build. I know nothing about paints, primers and finishes in general. I note that your last post on the topic was years ago. What's the latest and what do you recommend?

It really depends on what you want to get out of the paint. The System Three LPUs are "okay" smaller selection of colors, and I've seen a few minor issues with them. If you want to go for what the pros use I'd suggest Awlgrip. EMC is also good, and repairable (it's comparable to the Awlcraft line from Awlgrip)

I would not use the System 3 LPU's. Cracker Larry used it on the inside of No Excuse and I am having to repaint it. Go with Awl Grip or EMC for a longer lasting finish. For primer nothing beats the Silvertip Epoxy High Build Yacht Primer sold here.

>8 Years is still not bad for a paint job. As they say, you get what you pay for. The awlgrip probably lasts a good 20 or so if well kept.

With apologies, I'm going to repeat what I've said elsewhere and put in a word for us paupers. All the LPU's are very expensive so if you, like me, anticipate your boat not being kept in a velvet cradle in a humidity controlled shelter, you may, like me, wish consider a less expensive option. Of course, you've put in a lot of effort and you want the paint to last and be great looking, and may consider cheaper paint a false economy. But after a few run-ins with pilings, dock rash, and oyster shells and rocks on the beach, even the most expensive paint will be driven to submission.
I used Interlux Brightside. It took several coats for me to come up with the right application process but now I can do it very quickly with ease. It really looks amazing if you do it right. The Brightside I put on the shear stripe of my big boat looked good for ten years.

Another paint related question - can I overlap topside paint over epoxy+graphite (sanded first) or do I need to prime the epoxy+graphite first?

No need to prime as long as you rough it up with sanding first.

Question: Why are you putting paint on top of the graphite? It doesn't need further UV protection and the paint won't be as hard as the graphite/epoxy.

I think he's just working out the overlap procedure.

I overlapped the lpu topsides with bottom paint. Sand prep the area of the overlap first and prep as required. Then i sand prepped both (cured) carefully, and painted the bootstripe over the meeting of the dissimilar paints. Topsides and bootstripe are still stuck, but the s3 lpu on the deck and 'sun surfaces' did not handle southern sun well. Cracked and flaked. Just started to need some care on the topsides. If I paint again anytime soon, it may be emc, not s3 again. But the s3 primer is nice. If you try to find out if a finish system is compatible with it, don't expect much official help from a company. They want to sell their own primer for their own finish system. I understand that. But I sure do like how easy the s3 primer is to use and shoot.

terrulian wrote: ↑Mon May 15, 2017 4:26 pm Question: Why are you putting paint on top of the graphite?

Rather than taping off just the underside when applying the graphite+epoxy, I went ahead and covered the entire outside of the hull (SK14). The thought was that having the graphite under the paint on the sides wouldn't be a bad thing.

I don't know if you would get the best adhesion to a graphite epoxy layer. Primer is typically in part meant to stick well to a structural substrate and also provide good adhesion for the finish layer. So... The techies at the finish company will probably recommend their primer over the epoxy graphite seal (calling that the structural substrate), and then their paint on their primer. And I can understand why. S3 told me years ago that their lpu should be fine directly on their epoxy, without a primer. 'Their epoxy.. Their paint'. So...

I suggest that results will endure better with primer, then paint, where you are going to paint over the graphite. But it will add weight. And it will only endure as good as the paint system, of course.

Almost done! Congratulations! Be sure to post some pictures as you finish up and launch.

This is a great read.... Good points and help on painting..... and paints.