Varnish prep and first coat

[JetStream]

I know that varnish is a hot topic among boaters and has been discussed at length here. I have a question about first coat. In most of the articles I've read, it says to use varnish thinned to about 50% for the first coat(s). Others say to use a sanding sealer. I just received an E-Mail from my brother (a pipe organ builder and master woodworker) describing his method of finishing. Here is his method in his words:

I sand with 100 grit, then 220. Then I vacuum, so as to not raise too much dust, then blow off with 100 psi air to get all dust out of the grain. Then I wipe with a good rag and blow off simultaneously, which gets more dust out of the grain. Then I brush on a coat of thin shellac, which is the best primer for varnish. (You have to use a bristle brush for this.) After the shellac gets sanded with 220, the varnish goes on. I usually use gloss for the first coat; this gets sanded with 220 after overnight drying, then the second coat (usually satin) is applied.

My question is about the shellac. I've never heard of it being used as a primer and wonder if maybe it would only work inside with no UV. Comments?

[Ceasar Choppy]

Assuming you are talking about exterior wood, the big difference between your boat and your brother's method is that you need to seal the wood against moisture. Thinning the first few coats of varnish allows it to get soaked up into the wood. I don't think one coat of shellac is going to do that.

If you are talking about interior wood, you could probably get away with your brother's method since, *presumably* the wood won't be subjected to the UV and moisture the wood outside gets. I've noticed on my Pearsons that they used some sort of stain type stuff on the interior to get all the wood color to match. The interior wood never had sealer coats applied. For inside, I usually put at least a couple sealer coats on just out of habit.

I like his method of cleaning the wood.

[Jason K]

I've varnished with the first coat thinned 50%, the second 25%, and the third 10%. As Ceasar Choppy mentioned, the goal is to allow the wood to soak up the varnish as you build the base coats. Wood, particularly new wood, will soak up a remarkable amount of varnish.

It seems shellac would not soak up as readily and would be more accomodating to moisture intrusion. Some people will seal the wood with unthickened epoxy prior to varnishing, though, which is certainly a better choice than shellac.

The epoxy question was raised in THIS THREAD

[Ceasar Choppy]

I was reading through that old thread and, though it might be more appropriate to comment in that thread, I figure more folks are likely to read this one:

1. Schooner is real varnish. Used it for years with excellent results.

2. The Ephifanes wood finish gloss works well, but seems to darken things up a bit for me. But I only use it to build coats. Finish coats with the clear gloss works a treat! (I've switched from Schooner with the new boat just to experiment a little.)

3. I've had good luck with epoxy as a sealer coat on old wood (spruce spinnaker pole). I actually thinned the first two coats of epoxy with a little acetone. Third coat straight epoxy and then 9 coats of varnish. Not sure if there is much of a difference between using epoxy and using 2-part polyurethane. It does suck when water eventually penetrates and you gotta take it all off.

[Tim]

Because this is a forum about boats, I'm going to assume for the purposes of this discussion that you are talking about exterior wood finish on a boat.

Shellac is great for many things, and traditional orange shellac imparts a wonderful, rich color to many pieces, particularly to antique wood. (There's also clear-ish shellac with less or no color). You just can't match the depth that a shellac/polyurethane finish can provide on interior pieces.

Shellac finishes, however, are not water resistant. Nor are they UV resistant. Have you ever put a glass down on an older piece of furniture and gotten the white ring? That's the shellac turning white. Likewise, the color change of old furniture if left in a sunny spot is often the result of a non-UV resistant finish.

I would hate to see your varnish turn white in the first rainstorm. Shellac is alcohol-based, and does do a good job of soaking into and sealing the grain of the wood to help ensure a smoother overall finish. But you shouldn't use it outdoors.

Your brother's methods are excellent for indoor pieces, and probably pipe organs. Clearly, he is detailing the methodology that works well on furniture, evidenced by his profession and his use of satin varnish (which doesn't hold up well outdoors). I've used a similar finishing approach on some furniture pieces. But there's a large difference between furniture finishing and the rigors of outdoor and particularly marine life.

I believe that thinned varnish is the best way to begin your buildup. I and many others have had good luck with this approach. I am not in favor of the epoxy primer approach because I feel that water will always, eventually, get behind any exterior wood finish, thereby requiring removal; I don't relish removing epoxy. Stripping plain varnish is bad enough for me!

Sanding sealer is basically thinned polyurethane varnish. I don't think polyurethane varnish has any place on a boat's exterior; it lacks the necessary UV protection. You get the same effect as a sanding sealer when you apply the 50% thinned coat of varnish. It seals the wood grain, and soaks into the wood; it's an important step in the long process of building up a fine, clear varnish finish.

[JetStream]

Great answers!! Thanks very much. I suspected that shellac might be hygroscopic and thus not suitable for outdoors but didn't have any data. Maybe his grain cleaning methods will help someone and if someone is doing some non-marine work, the rest might be profitable. Again, a great forum for quick and knowledgeable answers. I thought it was interesting that my title on the forum came up as "master varnisher" for the post.

[keelbolts]

I have used epoxy under varnish. West makes a special hardener for epoxy that is to be clear coated. Removing the epoxy is MUCH easier than removing poly varnish. I strip with a heat gun & a ProPrep scraper. When you hit epoxy with a heat gun, it simply crystalizes and blows off.

My Grandfather told me of varnishing in the pre-war US Navy and his first coat was shellac. Numerous coats of varnish protected the shellac from the elements. Years later, I read of the technique in an old book. I don't know why, but I haven't tried it.