Capt'n Pauley's Pages

Varnishing Woes

by Paul Esterle

It seems like this was the week for varnishing questions. Several customers showed up at the boat store this week, complaining about varnishing problems. The first one came in with a piece of teak trim from his sailboat. He had coated the wood with epoxy and then applied several coats of varnish on top of the epoxy. Unfortunately, the varnish never cured. My daughter also experienced this problem. Another customer was tired of dealing with re-varnishing or recoating with other types of finishes and was looking for something more durable. 

Since there is one possible solution to both problems, I’ll cover both questions at once. There is a school of thought that considers varnished wood to be the best looking protection for wood aboard boats. Others use a variety of teak and wood coatings: Cetol, Armada, and teak oils are common material. These products all require attention and recoating on a regular basis.

The upkeep required for a varnish finish is due to several causes. Wood expands and contracts as it absorbs or releases moisture. This constant flexing eventually causes the varnish to crack. UV rays from the sun also attack the varnish, causing loss of gloss as well as contributing to cracking. Once water finds a crack or break in the varnish, it will begin to stain the underlying wood and further break down the varnish. While the best varnishes are formulated to resist these attacks, eventually they break down and require re-coating.

I have some friends who have their boat docked in Tarpon Springs, Florida. The UV is so intense down there that the varnish on their exterior wood required recoating every three months or so.  It finally got so bad that they painted their wood trim, so much for the great varnish look.

Getting the deep “look” expected from a quality varnish job requires building up a number of coats of varnish. Some suggest eight coats, others twelve. My wife, who does all the varnishing on our boat, puts on a coat a day and sands between most coats until she gets 6 to 8 coats applied.

So what is the answer to these folks varnishing problems? Well, more and more people are using a combination of epoxy and varnish to achieve the “look” with acceptable coating longevity. Three coats of epoxy combined with three coats of good varnish can equal twelve or more coats of varnish.

Applying those three initial coats of epoxy to all the surfaces of the wood provides several advantages. First of all, the epoxy helps seal the wood against moisture changes and the resultant wood shrinkage and expansion. Secondly, the epoxy hardens chemically, not by drying. This allows thicker coats to be applied more often, reducing the overall time for finishing.

Prepare the wood much as you would if you were going to varnish. Clean, bleach and lighten as necessary. If badly neglected, you may have to sand the old, gray surface off to get to sound wood.

There are several things to watch out for during the application of the epoxy, especially the first one. Make sure the wood is clean, dry and free of grease and oil. In the case of teak, this means washing the wood in acetone to remove surface oils. Warm the wood before applying the epoxy. If you coat wood with epoxy and place in the sun to harden, the air in the wood expands and forms bubbles in the surface. If the warmed wood is coated with epoxy and cools, the epoxy is sucked into the wood pores.

Another source of bubbles in the epoxy finish is whipping or beating the epoxy/hardener mixture. It needs to be thoroughly mixed, but try not to whip air into the mixture. I always use foam brushes to apply the epoxy to the wood. Keep an eye on the coated wood and pop the bubbles if they appear. Its either that or extensive sanding between coats.

A major problem with epoxy is that it has no resistance to UV rays. Epoxy exposed to the sun will soon turn cloudy and then begin to break down. If it weren’t for this failing, we could get by with nothing more than several coats of epoxy. The reason for over-coating the epoxy with varnish is to provide that necessary level of UV protection.

Make sure that the epoxy/hardener combination is compatible with the varnish you plan to use. To name names, my daughter coated her cabin sole with a WEST 105 epoxy resin and 205-hardener mixture. She then tried to coat it with Interlux #60 and #95 varnishes. Neither cured properly. After doing some research, I found out that those combinations were now incompatible. Since I had used this very same combination several years ago, something in the varnish or the epoxy had changed. So be warned, always do a test piece to verify that your choices are compatible.

In my daughter’s case, she was able to use Minwax Polyurethane Floor Varnish since the application was below decks and not subject to the sun’s UV rays. That is not an option if your wood is exposed to sunlight.

For the ultimate in looks and protection, consider using a two-part polyurethane varnish over the epoxy. Interlux Protector was the product recommended by the Interlux customer service department. The two-part polyurethane’s have excellent UV resistance and are ideal for application over epoxy. This is probably the nearest thing to a permanent coating there is, even though the 2-part varnish is much more expensive than regular varnish.

To recap, here are the steps involved in an epoxy/varnish finish (see the drawing below):

1. Clean and prepare wood thoroughly, sanding, cleaning or bleaching as required. Make sure to clean off any old sealant if you are refinishing existing trim.
    
2. Make sure wood surface is clear of moisture, oils, grease and dust. Wash teak in acetone to remove surface oil prior to applying epoxy.
    
3. Apply three coats of WEST 105 resin/207 hardener to all surfaces of the wood. You can apply the next coat of epoxy while the last one is still tacky. Apply an even coat with a foam brush, avoiding drips and runs. Watch out for and pop any bubbles in the coating.
    
4. Allow the epoxy to thoroughly cure, at least 24 hours.
    
5. Wet sand the epoxy with 150 grit wet-or-dry sandpaper. DON”T sand through the epoxy!
    
6. Apply three coats of varnish or polyurethane according to the instructions on the can.
    
7. Reinstall wood trim. Make sure that all fastener holes are epoxy coated to prevent water penetration. Use a good sealant and good sealant techniques. Don’t use 3M5200, as you’ll probably destroy the trim next time you try to remove it for refinishing.
    

I won’t claim this is a final solution to getting a good looking deep varnish look on your woodwork, but it’s one of the best solutions available right now. I have to admit that we haven’t yet completely switched to the epoxy/varnish solution on our boat. But my wife did sew covers for all the exterior teak (handrails, etc.). Good luck with your re-varnishing!

Paul Esterle (www.captnpauley.com) is a freelance boating writer and “man for all vessels” with many years and a wide range of boat maintenance experience. He publishes in popular magazines such as SAIL, Blue Water Sailing, and Good Old Boat, and is Technical Editor for Small Craft Advisor Magazine. In addition, Paul has produced a series of boating related videos and CDs, including the instructional video used by Spartite(TM) at boat shows. Paul has also hosted seminars and lectures at various boat shows and marine stores.

Paul can be contacted directly at pesterle@preferred.com with any questions or suggestions.

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