Two-part acrylic/urethane paint

[Brett in Bangkok]

I'm thinking of using two-part acrylic/urethane over the epoxy on the hull and sides of my boat. I got this stuff for free so no loss if I don't use it. Has anyone used this stuff before? Is it ok on epoxy?

Thanks, Brett

[formerlyknownasprince]

Looks great till it peels. What do you do then?

Ian

[thechemist]

Look on the label in the cautions/warnings section, to see that it contains aliphatic isocyanate monomer and polymer. That's the good stuff.

Coverage should be not more than 300 square feet per gallon to give adequate film thickness.

Special adhesion-promoting primers are required to give good adhesion. The same primer used on aluminum [aircraft] should do fine over sanded epoxy or GRP [Glass-Reinforced Polyester]. Perhaps you can get some from the same source as the paint?

[paul oman]

The only urethane better is a polyester urethane such as algrip or LPU 100 (by Progressive Epoxy Polymers).

Next step down are the acrylic urethanes.
FYI Amron (spelling???) - a common alternative to awlgrip, is an acrylic/polyester blend urethane.

hope this helps!

paul

[bainbridgeisland]

Brett, what kind of boat do you plan to use it on? Not that this makes too much difference. I am just curious what you are sailing over there.

I used to know Fireball dinghy sailors in Thailand. They had some nicely built wooden boats that were reasonably competitive in World Class competition.

[JimD]

Originally posted by thechemist:
[QB]Look on the label in the cautions/warnings section, to see that it contains aliphatic isocyanate monomer and polymer. That's the good stuff.QB]If its that toxic its gotta be good. I used a 2 part polyurethane clear coat containing the above mentioned recipe for the brightwork over epoxy/fiberglass. No sign of peeling so far. A few issues back WB had an article on a company using urethanes over epoxy on rather expensive runnabouts. If you're in Bangkok I'd not be surprised if the product labelling isn't up to our standards so maybe hard to tell what you've got.

[Buddy Sharpton]

I've used both pigmented and clear 2 part.acrylic urethane. The clear went over WESt epoxy coated teak tyhat had been de blushed and wet sanded with 120 grit. 3 years in, it looks and stickes great. The pigmented has been applied over good gelcoat , well wet sanded and on a cold molded wood hull with epoxy/6 oz.fiberglass skin I used a 2 part epoxy primer, Interlus 400/414. You have to get a uniform base color anyway because the top coats aren't very opaque and you would need so many coats-this stuff is hard, but thin. Holds up great for ten years at least so far, and this is Navy Blue in the sunshine.

[Brett in Bangkok]

bainbridge, I'm building a Stevensons' plywood Skipjack. I mostly sail a little dinghy I built a year ago. I've sailed a few Hobies here, although Nacras are the most popular. Not a lot of small monohulls here in the north. There may be more down Phuket way.

JimD you're right. No information on the can (at least that I can understand). This tends to be a place where you need to get a facts sheet from the manufacturer - rarely anything on the can.

Thanks for that Buddy. Difficult to get the right primers here. I am hoping to apply the paint directly on prepared epoxy. I'll probably use a good enamel on the hull and stick with the two-part on the inside/rudder/daggerboard.

Brett

[bainbridgeisland]

[QUOTE]Originally posted by Brett in Bangkok:
[QB]bainbridge, I'm building a Stevensons' plywood Skipjack. I mostly sail a little dinghy I built a year ago. I've sailed a few Hobies here, although Nacras are the most popular. Not a lot of small monohulls here in the north. There may be more down Phuket way.

They used to have a fleet of about 40 Optimists in Satahip and a dynamite fleet of racing dinghies at the Royal Varunna Yacht Club in Pataya. Boy I hope my spelling is close enough for you to tell where I am talking about.

The locally built boats in Thailand used some of the best plywood I have seen. They did have trouble getting lighter density woods, but top quality was available for the rest.

[Buddy Sharpton]

Don't short change yourself on the wonderfully durability of acrylic two part on the topsides, the part which is the first that people look at and the first to get a lick. Wouldn't use anything but a two part on top of an epoxy/glass surface. You can get great adhesion without the epoxy primer- it's just that 2 part urethane is very thin and will show all the flaws. The epoxy primer is a high solids, sandable paint which can be like a mini coat of fairing compound which can relatively quickly be sanded to a relatively faultless finish. You'll have to use many more coats of a hard to sand 2 part urethane to get this level of smoothness. But, if you are willing to move closer to the workboat end of the wookboat to yacht finish spectrum of painting, there's no reason to fear n adhesion problem putting the urethane directly on top of the epoxy. Just wash off all blush thouroughly before any sanding, and then sand, finishing with no smoother than 120 grit. I like snading with a foam ad on a RO sander hooked up to a vacuum. Earphones and a CD help get the right frame of mind for this mindless work.Wet sanding by hand is slower, but still dustless.

Any smoother is risking adhesion. The snading scratches will show through the first layer on the urethane. I would let each coat cure overnight and then wet sand with 220 to remove dust nibs, bugs and the occasional sag. Three trips around should do it, but if you are using a red or bright blue, you may find their hiding power is less and more coats are needed. White is easiest to get an acceptable finish, weathers the best, and is easiest to repair. Big surprise! But if you still want a navy blue boat- 2 part is still the way to go. I've done white, red, navy, forest green and bright blue. Still waiting on a yellow one.