Marine Varnish

[Kurt Rosenzweig]

Quick question guys. I'm making am exterior sign from mahogany. Can I put a marine type varnish over BLO? I really want the grain to pop and figured blo would do it, but am a little concerned what top coat to use. It's going to be in a coastal environment and want to hold up. All input will be greatly appreciated. Thanks

[John Coloccia]

I would maybe just do the spar varnish, to be honest. I think BLO starts to yellow when you leave it out. Also, spar varnish will contain Tung oil (at least traditionally it does), and that should do a fine job of bringing out any figure right on it's own. Try it on a little piece of scrap.

[Howard Acheson]

Yes, an oil based varnish can be applied over BLO that has cured for 5-7 days. Use a real, non-poly exterior marine varnish. Poly varnishes are rapidly attacked by the UV in sunlight and the finish will rapidly become more amber, get cloudy and then begin to crack and peel. Do not use anything you get at the big box. Go to a marine supply store and look for brands like Wolsey, Interlux, Pettit or, best of all, Epifanes.

Even the best finish will last only 2-5 years. To maintain protection and appearance, scuff sand the surface when it begins to get cloudy and apply a couple of more coats of finish.

[Bill White]

Pay CLOSE attention to Howie. He's nailed it dead on.
Bill

[Ron Natalie]

I agree with the rest. I have a wooden boat and when Interlux discontinued the varnish it has been done with, I switched to Epiphanes. If you don't have a marine store nearby, I notice Lowe's is stocking Rustoleum's marine varnish. I've got a can, but I've not tried it yet (I've got a couple of doors on the house to do). It's a lot cheaper.

As stated, every couple of years you clean it well, run over it with one of those ScotchBrite between coat pads (the one equiv to 0000 steel wool), and throw a couple of new coats of varnish on it. Probably not an issue on the sign, but on a large flatish (like the side of a boat) surface you can throw the scotchbrite on the h&l pad of your DA sander to speed the job along. On the big boat surfaces I use a very thin foam roller (the kind they sell for epoxy) to apply the varnish to a small are and then tip it out with a foam brush.

[Dell Littlefield]

I agree with Howard, I had bad experiences from using polyurethane marine varnish.

[Jeff Duncan]

I don't like oils like BLO as they take too long to dry for my liking. I'll usually use a thin coat of shellac to make the grain pop, then apply a finish on top of that. Not sure how that would fare with the marine varnish though?

good luck,
JeffD

[Roger Feeley]

I seem to remember that FWW (maybe Fine Homebuilding) did a piece some years ago about outdoor finishes. The winner wasn't what you would expect. They used an oil base paint without pigment. Deep Base, perhaps? All I remember is that it was an unpigmented oil based paint. It beat out spar varnish and all sorts of other stuff.

[Sam Murdoch]

To support what Howard has written, here is a good link on the subject: http://www.thewoodwhisperer.com/articles/difference-between-spar-varnish-and-regular-varnish/

[Eric McCune]

As Roger mentioned, an oil based, deep base paint with no pigments is a great choice for a clear outdoor finish. It goes on a little cloudy but dries clear. I used on Douglas fir doors on my shop and 1.5 years later the finish looks perfect.

http://community.woodmagazine.com/t5/Steve-Mickley/quot-Paint-quot-your-exterior-projects/ba-p/1657

[Jerome Hanby]

I saw an article in Wood magazine about doing the same. Keep meaning to get a can to try out. I've got some benches that I'm rebuilding and need a finish...


I seem to remember that FWW (maybe Fine Homebuilding) did a piece some years ago about outdoor finishes. The winner wasn't what you would expect. They used an oil base paint without pigment. Deep Base, perhaps? All I remember is that it was an unpigmented oil based paint. It beat out spar varnish and all sorts of other stuff.

[Brian Kent]

The Fine Woodworking article only had one really good result - Epiphanes varnish. Either on its own or over epoxy. Seven layers.

[Don Morris]

Epiphanes is expensive but it's the best.

[Kent A Bathurst]

Search for photos of Brian's sunburst table with Epifanes on it.

I used Epifanes on a WRC gate. Full sun from about 11 am - 4 pm. 2 years later, looks brand new.

[Larry Edgerton]

Even the best finish will last only 2-5 years. To maintain protection and appearance, scuff sand the surface when it begins to get cloudy and apply a couple of more coats of finish.

I strongly disagree.

I have had great success on exterior commercial doors with automotive finishes. First, I use West System for assembly to minimize movement. I prep the wood with water based finishes until it is how I want it to be, flat, pores filled, etc. Then I shoot it with clear adhesion promoter that designed for urethane bumpers and then shoot it with a clear UV inhibited automotive topcote such as Sherwin Williams 7000.

I have had exterior doors, on a bar that has seen millions of people go through it last over ten years. In a sign situation where no one is kicking it and hitting it with handtrucks and snow shovels it should last longer. Its very expensive, and you want to study up on how it is used, but the results defy conventional logic.

Larry

[Anthony Whitesell]

I seem to remember that FWW (maybe Fine Homebuilding) did a piece some years ago about outdoor finishes. The winner wasn't what you would expect. They used an oil base paint without pigment. Deep Base, perhaps? All I remember is that it was an unpigmented oil based paint. It beat out spar varnish and all sorts of other stuff.

Olympic Exterior Base #5 is the only one from the list I can remember. If memory serves, I only remember it because it was the only one specifically mentioned that is carried locally.

My father tried it on the front door sill plate a few years back. Each time I go to the house I take a second to see how it is holding up. Still looks good to me.

[Ron Natalie]

There is much controversy on this isn the classic boat community. We've got a local shop that uses automotive clear coats and boy the stuff does look nice. I don't know if I could be convinced to do my boat in it, but for a sign I wouldn't hesitate.

Be careful, automotive urethane is NASTY stuff health wise. Use an appropriate respirator. It doesn't have enough of an odor to give you warning.

[Anthony Whitesell]

For the race cars I run, we use an automotive clear coat. We found the softer clear coat lasts longer when being beat on. The harder grade sands smoother and glossier, but cracks and pits easier.

[Rob Sack]

Does anyone have any more info on using automotive clear coats?

[Larry Edgerton]

The caution about the health hazzards are an absolute. Know what you are doing and if you don't have a booth spray outside with brand new resperator cartridges.

I used the softer stuff on our off-road race trucks for the same reason, and in fact that is what made me try it on wood.

I liked the S-W 7000 because you buffed it while it was still sort of wet. Not sure if it is still available. You could touch the surface and move the film around, and that is when you hit it with an eggcrate wheel. It magically flattened out and was perfect, while still only surface dry. Cool stuff.

Restoring cars has always been something I have been into, so I really already had my learning curve out of the way when I first used it on wood. You want one that is compatable with plastic or fiberglass as it will be more flexible. Spraying it is pretty much like spraying lacquer, you have to be fast and have a plan. As far as the actual spraying goes it is no more difficult than anything else, anything automotive that is. It will be thinner than your typical wood finish, so you will use a finer tip. Brushing is out of the question, not happening. Pay very careful attention to the mixing instructions. some finishes can use up to four parts. You are goint to want to come up with a way to roll the piece so you can do a continious spray ahead of time. It makes a better film and cleanup is a pain. I have a system for doors that lets me roll them with one hand as I spray.

A suggestion is that you find a body shop and offer to do some manual labor [cleanup, woodwork, etc.] for them in exchange for some education and maybe spraying your first project for you as you watch. This is how I learned a lot of what little I know about body work, and I still pick these guys brains when I need it.

If you go this route, DO NOT use the baking booth to cure the finish. Guess how I know this.

You may want to check out the BASF line of waterbased finishes. Lots of body shops are switching to them, but I have not tried any of their products myself yet. I would want to find out about elasticity of the finishes first, as that is important with wood. No finish is 100% moisture resistant, so when the wood moves you want the finish to move with it.

Coat/soak all of your end grain with West System first. It is the superhiway for moisture into the interior of the wood, so I fill the endgrain and this has worked for me in extreme enviroments.

Larry