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davidpm 02-17-2012 11:04 PM

coating with epoxy
 
I've been building a little dinghy for some time and sadly no matter how slow I try to go it seems to be getting closer and closer to my having to finish it.

This is a stitch and glue design with marine ply. It is designed to be encapsulated with epoxy then painted except for the bright-work trim.

The plans and west system directions call for several coats of epoxy.

The problem I'm having is that you are not supposed to thin epoxy but it always seems so rough.
I put it on with a west system roller and tip it out to get it as smooth as possible but by the time I sand it so it is smooth it seems as if I sanded most of it off.
I'm thinking I will just do three or four coats without sanding to build up some depth before sanding. Since I'm doing this an hour or so at at time I can't time these west system coats to wait for it to get tacky before the blush.
So I'm thinking of switching over to system 3 epoxy which does not blush and just do a pot every night until I get three or four coats then sand it smooth which will take off the last coat for sure.

Does this sound like a plausible plan?
I have to switch to system 3 epoxy anyway as it is required as a base for the system 3 LPU paint I'm planning on using.

I'm planning on using the system 3 LPU paint which is a two part water based paint which I'm told will not smell too bad because I'm working in the basement and don't want to stink up the house.

Lake Superior Sailor 02-17-2012 11:10 PM

What the epoxy doesn't smell up the house?...Dale

bljones 02-17-2012 11:13 PM

change your west system hardener. 207 hardener doesn't blush. It also lays better, needing less sanding and better coverage.

WEST SYSTEM | Epoxy Hardeners - 207 Special Coating Hardener

Don't roll it on. use a squeegee. Work it, wipe off the excess, done.

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bljones 02-17-2012 11:15 PM

If you plan to beach your dinghy, don't worry about 2 part paint. You want something field repairable, because it will get scratched and scuffed.

overbored 02-17-2012 11:53 PM

you don't need to put that many coats of west on. all you do with it is seal the wood then you go to a primer and paint system to get a smooth colored surface. the bright work is done by coating the west system with coats of clear uv varnish which gives the smooth shiny surface and protects the west from the UV.

davidpm 02-18-2012 09:36 AM

Quote:

Originally Posted by bljones (Post 833098)
change your west system hardener. 207 hardener doesn't blush. It also lays better, needing less sanding and better coverage.

I'll check that thanks.

I noticed that guy with a squeegy finished up with a roller.

deniseO30 02-18-2012 09:54 AM

David, 207 hardener also has UV blockers. Any 2 part urethane paint will bond to epoxy by the way. Some one part paints won't dry 100% and stay tacky forever, so you will want to test the paint first.

SloopJonB 02-18-2012 03:00 PM

Quote:

Originally Posted by deniseO30 (Post 833187)
Some one part paints won't dry 100% and stay tacky forever, so you will want to test the paint first.

???????????????????????? Can you elaborate?

CalebD 02-18-2012 04:02 PM

A bit involved but maybe worth trying.
You are trying to build up a smooth epoxy layer. What if the epoxy hardened in an absolutely smooth surface that required little or no sanding?
I've had some luck with this method on smaller repairs.
Get a mold release agent McLube : Mold Release and some panels of plexiglass that will fit over the flat sections you are coating. Lay the epoxy on as evenly as possible then spray the mold release on one side of the plexi and lay the plexi down on the epoxy. Use some weights if you have to so the plexi sits flat and comfortably while covering the epoxy. Once the epoxy hardens you should be able to remove the plexi (hopefully in one piece) leaving a smooth surface that needs little or no sanding.
This technique works pretty well with Bondo as well.
Other plastic panels should also work for making mold shapes. I've used thin plywood (1/16") so it could be bent to match the shape of a hull but it is hard to get all the ply off the epoxy once hardened which leaves you with some sanding to do.
YMMV

bljones 02-18-2012 04:20 PM

Quote:

Originally Posted by davidpm (Post 833182)
I'll check that thanks.

I noticed that guy with a squeegy finished up with a roller.

backrolling to level any streaky spots. Not the same as applying with a roller.

What are you building, BTW?


One additional benefit of 207 hardener is that you can hotcoat it.


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