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System 3 water borne 2 part linear polyurethane


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Don asked me to start a thread on this stuff. Can't say I am an expert, but I probably have more experience and luck with the stuff than most.


A few things to consider before even using it.  It will never match solvent based when it comes to gloss. If you must have a mirror, it won't satisfy you. There is a clear coat, and fanatics can do the super fine sanding with clear coats to finish.  But it will still not match. But if almost as shiny, but safer seems good to you.   System 3 is a lot harder than one part polys, but not quite as hard as solvent based. That being said, I like semi-gloss. This is especially so for my Lapwing which is a classic look, and planks vs. big smooth hull. The biggest plus as I see it is there are no isocyanates or Xylene.  Isocyanates are the big unknown.  They are proven carcinogens, organic vapors cartridge masks do not filter them out of your air, and they have no smell. Professionals wear a full suit and supplied air. There is more study needed here. Yes, they are much safer rolled and tipped vs sprayed, but no one seems to know where a safe place to put the line is.


What I have learned about rolling and tipping System 3:
1. System 3 does not go on well in high humidity, humidity cures it too fast.

2. System 3 does not go on well in any amount of breeze, cures it too fast.

3. System 3 does not go on well in high temperatures, cures it too fast

4. No 2 people working together can go too fast to keep a good wet edge, they sure can go too slow.

5.  The hot recoat time is fantastic.  It is days down to less than an hour. So if you did want that super finish, no sanding till all the coats are done.

6. They suggest thinning it.  YES!!!!!! You may get some drools during rolling, but it will have started curing so fast you will still be racing by with your tipping and it won't get a chance to drool after that.


The ideal day is no wind, 50°, low humidity and cloudy.


Because I paint my Lapwing 1 plank at a time, and can alternate sides, I can paint solo.  I don't keep a wet edge from plank to plank, just along each plank.  When I painted my Renegade it was large smooth continuous surface.  This is where it gets fun.  Even under those ideal conditions, and the planking all set up on both sides. It was a race to get from bow to stern without drag marks. My partner rolled vertically and moved fore to aft. I tipped horizantally and followed him as fast as I could. The result was a quite smooth semi-gloss.  For tipping I used a badger hair brush and made sure not to let anything cure on it in the process.  Have a bucket of water handy.  A wet brush doesn't hurt, just don't slobber the water as you go. A SS wire brush helps clean the tipping brush. To say that having all these things handy before you start is a good idea would be an understatement.


Anyone with experience please chime in.

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Thanks for the details, Hirilonde.  I thought that higher humidity would have been beneficial.  That was one if my mistakes.  I did like the lack of fumes when I used it, and the ease of cleanup.  But I bailed out on using it because of the nasty brush marks I was getting.  

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I've had good results with their silver tip yacht primer and LPU using the roll and tip method.  Admittedly, I was only looking for the hand painted look and not a mirror finish.  Both want to dry quickly but I was able to manage that by painting first thing in the morning.  The LPU seemed to be more sensitive regarding temperature and humidity than the primer.   My best LPU results (no brush marks) were on rainy 60F Seattle days.

The LPU bright colors don't suit me so I've also used Marshals Cover Marine Enamel rolled and tipped over the silver tip yacht primer with good results. 


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