varnish or polyurethane

Posted:
Sat May 26, 2007 7:34 am
by drikwah
I am building a woody, I am planning to stain it then clear coat with varnish or polyurethane. Which is better. after two coats of the clear there will be a final coat of clear epoxy resin. All outdoor UV stuff.

Posted:
Sat May 26, 2007 9:17 am
by Airspeed
If you are going to use epoxy,why do you want to use a varnish or polyurethane under it? Are you going to stain it first? If so I would stain it and then just use the epoxy. I have used fiberglassing resin to seal up some small boats I have built and it worked great. I would still keep it indoors or covered well during the winter,one little crack will get big fast.
Aaron

Posted:
Sat May 26, 2007 1:03 pm
by Ira
Aaron's right --and just looking at his album confirms the fact that he knows what he's talking about. (Man...I HATE that bastard because his TD looks so good!)
Epoxy is the real deal, the heavy-duty stuff, and you wouldn't use it over thane or varnish.
I myself just used Pratt & Lambert's Vitralite Marine Spar Varnish, which is even meant for use UNDER the waterline of boats (transoms and such), and has a 30-year UV protective rating.
The stuff isn't cheap, but in the hands of someone who knows what he's doing, it'll come out great. In my hands, it came out okay.
But unless you're going to go the epoxy route, I wouldn't commit myself to staining yet. Varnish and thane are gonna affect the color/tone of the wood in ways you haven't imagined, and depending on the wood you're using, that might be all you're looking to accomplish.
I used beaded birch for my side skins, and bendy birch for the roof. It gave me the color that I wanted, without staining. If you want darker, of course, go ahead and stain.
But make sure you test first on a DECENT SIZE piece of scrap with the stain (then the varnish, thane, OR epoxy) to make sure it looks like you want it to look. A 10-inch piece of scrap is gonna be deceiving. You need a bigger hunk to get a good idea.)
The last thing you want to do is stain your whole TD and then discover that you don't like it, because you simply can't UNDO stain at all. Let alone what you're putting over it.

Posted:
Sat May 26, 2007 1:21 pm
by madjack
Epoxy, is not UVie proof and must be protected by something that is...hence spar varnish or an outdoor rated polyurethane or an auto clearcoat paint...so stain>>>epoxy>>>varnish/epoxy/clearcoat...is the order you should work on...keep in mind that epoxy is not compatible with many oil based stains...a water based stain, applied and allowed to thoroughly dry is the best bet...you can also skip the epoxy step altogether(not recommended) and just use the varnish or urethane, however you will haveta redu the finish every so often depending on exposure time to the elements.....
madjack


Posted:
Sun May 27, 2007 8:09 am
by Ira
madjack wrote:so stain>>>epoxy>>>varnish/epoxy/clearcoat...is the order you should work on...keep in mind that epoxy is not compati
Explain this again--how did that second epoxy get in there?

Posted:
Sun May 27, 2007 9:56 am
by madjack
Ira wrote:madjack wrote:so stain>>>epoxy>>>varnish/epoxy/clearcoat...is the order you should work on...keep in mind that epoxy is not compati
Explain this again--how did that second epoxy get in there?
...there was an attack, led by Major Confusion and followed up by General Disorder....

........
p.s...that second "epoxy" should or read 'urethane........MJ

Posted:
Sun May 27, 2007 2:32 pm
by Steve_Cox
I put on 5 coats of Helmsman Spar Urethane about a year and a half ago when I built and the grain in the red oak plywood is starting to raise a little in the tighter radii in the front. I keep the TD in a garage. I suspected when I built it I would have to sand and re-coat in a couple of years. I've got a few scratches here and there anyway so the re-application of Spar Urethane won't be a bad thing. There are no problems where the plywood skin is flat or on the bigger radii.

Re: varnish or polyurethane

Posted:
Mon May 28, 2007 2:54 am
by doug hodder
drikwah wrote:I am building a woody, I am planning to stain it then clear coat with varnish or polyurethane. Which is better. after two coats of the clear there will be a final coat of clear epoxy resin. All outdoor UV stuff.
The proper order if using epoxy is to "dye" (not an oil based stain), the wood first, epoxy, several coats, then clear coat it with varnish or whatever you decide for a UV protectant coat. Epoxy is not recommended to be put down on top of an oil based stain. It does provide great protection and depth to the finish on a woody, however, it does need to be top coated with a UV protectant finish, IE, varnish, or some sort of clear, auto clear is my choice, but there are others out there. Varnish typically does take some maintenance, depending on how much time your project will spend in the sunlight. Automotive clear won't need the routine maintenance like a varnish and if you get a scratch. hit it with a polish...but it does require the tools/equipment to do it. Doug