Originally Posted by happyendings
Actually one of the waterborne LPU paints DOES say boat
on the can--System 3 WR-LPU. Maybe it's just DuPont auto paint
in a different can?
The way I go about boatbuilding, is like the Gougeon Brothers... as a scientist/researcher. I make destruction samples of a proposed joint, and then hit it with a sledge hammer to break it. If the ply broke but not the glue joint, then it's OK!
I did the same thing to compare epoxy
resins against each other, in both impact and peel strength. Systems 3 was better for impact, but WEST Systems was better for peel strength.
I also tested solvent welding and caulk bonds, as well as glue bonds to various materials, as well as noting advantages between them in solvent resistance or UV longevity.
I even taped or held a thermometer under different canvass fabric
colors and later under different samples of painted clear plastic, to determine the "cooler" materials, and actually note the superior UV and heat blocking characteristics afforded by using grey primer rather than white under your topcoat.
EVERY aspect of my boatbuilding choices was thoroughly researched first, to get BOTH the popular consensus, AND manufacturers propaganda. (During this time... I read over 20 magazines or trade
publications per month, for more than 20 years). This took the first two hours of every day, while I drank my coffee, and was quite EXPENSIVE. Due to the problems avoided, it was money
THEN, after this research
calls "all over the world" sometimes, I did my own research
and experimentation to find my "own" results. Bear in mind... I am NOT a perfectionist, and CAN back off when it is called for. I am just an amateur scientist that got sick of school
, and took up boatbuilding instead. It has not made me rich, just fulfilled.
SYSTEMS 3 WATER
BASED 2 PART LPU:
I researched and tested the Systems 3 water based LPU back then too, thinking it may be the way to go. I first got their small test kit, and later a qt of primer and a qt of beige topcoat.
Using their small volume test kit, I primed and painted a 1' square sample of sanded epoxy/glassed plywood
. It was flat, as described, but a subsequent clear coat would have shined it up OK.
I set this in the middle of my pasture, facing directly at the sun, for 6 months.
After this period, I checked it out. It was colorfast, but chalking already. It would chalk up my hand when wiped. Based on this, I decided not to paint
Their test kit was so small, that they did NOT include catalyst in them. It is a VERY small ratio to the base, so would have been drops only. When I called them to discuss this, they said that the catalyst was not deemed necessary to making a test, so I "assumed" that this omission was not what effected the paint's UV resistance. This may not be correct, or it could be that the addition of the clearcoat would have given a different result. It made no sense to me at all, that the test kit did not include catalyst, no matter how small an amount.
I also tested the sample for paint adhesion with the previously explained crosshatch test, which it passed 100%, and I found it to be VERY hard and VERY tough as well. It did not like wiping with isopropyl alcohol so much, but did not dissolve. It was, however, quite resistant to other solvents, like gasoline & diesel fuel
, so I used my Qts of the stuff in the cockpit's subfloor fuel
compartment, (this time WITH the catalyst).
It has held up VERY well in this shaded but permanently wet area for about 18 years now, and neither small fuel spills nor the water have effected it. This last point would not be true of solvent based LPUs... They can stand anything BUT being perpetually wet with something over it, like a throwable device cover, or cockpit
seat cushion, or a fuel jug, for years. In this one application, with moisture trapped against it by something flat, solvent based LPUs will blister. They seldom pop, but look terrible. I switched to using just AwlGrip's 545 EPOXY
primer, (only under these items that trap moisture), OR used pure pigmented epoxy resin in my refrigerator's usually wet bottom, and in the anchor
lockers. These areas were shaded, and this permanently solved
the blistering problem.
In the cockpit's subfloor, as I said earlier, the waterbased LPU stuff did NOT blister. While not pretty the way it was just roller tipped in there, it is perfect for that application. I think it is even harder than AwlGrip!
In a phone
conversation with System 3's inventor/chemist/president, Kern Hendrix, he told me that he had painted his kit airplane with it, and loved the stuff. With 200 MPH winds and lots of solvent, his is a very harsh paint application!
Because Systems 3 LPU originally failed my UV resistance tests, I wouldn't just run out and buy it for painting the entire boat
. It would, however, make a PERMANENT but streaky/flat "waterproof/peelproof" paint job down below, in anchor
lockers or in refrigerators. THESE would be possible applications for the stuff.
IF you contemplate it's use on the outside of your boat, I would try to get at least 10 different testimonials from cruisers that had used it on their boats for over 10 years, (presumably with the clearcoat on top). This adds a labor intensive 3rd step to painting, so is far more work than 2 steps with solvent based LPUs, but without it, the results are almost totally FLAT, not a pearly semi-gloss.
These testimonials mean NOTHING, btw, unless they are all from full time liveaboard
cruisers that spent most of that 10 years in the tropics. If they all said that during that time they never got peeling or paint failure, just mild chalking after 5 years or so, and thinking about re-painting after 10, then I would definitely consider using the Systems 3 waterbased LPU. My results did not bear that out, but like I said, they may not apply.
This paint IS a lot safer than solvent based, and better for us all. When someone looks at their ENTIRE carbon footprint, however, their house & choice of car, are over 90% of it. Painting their one trimaran
just once every 10 or 12 years, with nasty ol solvent based LPU paint, would only make up a VERY small fraction of 1% of their decade long carbon footprint. In the big picture, this is a very minor issue in the life of an otherwise environmentally conscious person.
"Professional" solvent based LPU painters (that spray daily), on the other hand, are the big polluters that have a real impact on the environment
Water based LPUs for health
reasons sounds great, but I would still want an over 10 year lifespan, without any failure. In MY small application with it, it is perfect. Do your homework first is my advice, and make it an educated choice.
If anyone needs more detailed advice on this or other boat building/maintenance issues, I can go into more depth
for them by email
or on the phone. Many folks have contacted me "personally" for a consultation through CF, as this is now most of how I make a living.
Hope this helps,