Help clearcoating

I've been practicing staining and clearcoating on a piece of birch before I move onto my real piece. The problem is that everytime I add clearcoat, I get little rings in the surface as it dries. It looks similar to craters on the moon. Does anyone know what causes this?
Thanks!
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its sounds like fisheye. search the web for its causes and fixes. heres a cut and paste from the site i have bookmarked:
25.2. I have a question referring to fisheyes on paint. What exactly causes it? How can it be prevented? Fish eyes are caused by contamination usually containg silicon, that screws up the surface tension of the paint. To prevent them you need a very clean surface and a clean air supply. As a last resort you can use some fish eye eliminator, but use caution since it might result in loss of adhesion.
randy

I
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Aha, thanks! I'm working with birch vaneer and I accidentally sanded through the vaneer in a couple of places. I'm betting the glue underneath is what's causing this problem.

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Fish eye. Caused by any of several types of contamination on the surface of the wood that changes the surface tension of the finish over the area causing the finish to flow away from the contamination. Silicon is a primary candidate because once something is contaminated with it it's a bitch to remove.
Commercial fish eye eliminator will correct the problem but you have to be cautious with it since. It's usually a silicon and if you get it on anything else, including tools or applicators, that will, in turn, become contaminated and you enter a vicious circle.
Best bet is to seal it off from any subsequent layers is one or several thin and lightly applied coats of finish. Dewaxed shellac will work also. Saw an article on a couple of methods for doing so but can't pin it down right now.
--
Mike G.
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JR wrote:

I'm assuming you're spraying this? The other posts that suggest fisheye are good advice, based on what you've told us. In addition, if your compressor has not been drained, then make sure to drain it before spraying. Even water will cause fisheye. Drain your compressor, and make sure you have a water trap installed. I drain my compressor before every spray job, and at convenient points throughout a spray job as the situation allows. I also have a water trap in the line as well as one on my gun. I use those orange bulb type traps that you can find at any automotive paint store, or even NAPA on the gun. Those do the best at grabbing the smallest amounts of water - but you've got to get the tidal wave out of the compressor first. I keep one of those orange traps on each gun at all times and I've painted several cars with the one that's on my finish gun now - they last a long time.
--

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