Adhesive and Finish for a Teak Sink

Tips for good adhesion and protection for a sink made with Teak, a durable but oily wood. July 12, 2012

Question
A company wants me to make a teak sink. Simple design, rectangular and 5" tall. I was thinking of making box joints and using West System epoxy to put it together. But what about the bottom? It is going to be about 19" from front to back. Do I have to worry about expansion and contraction? Or is teak stable enough to just glue to it? It will be covered in a few layers of West System epoxy and then marine varnish. Unless someone tells me different, maybe teak oil.

Forum Responses
(Architectural Woodworking Forum)
From contributor A:
Box joints sound good to me. Simple, attractive, easy to machine, plenty of bonding surface.

I would coat the entire sink inside and out with epoxy. Let it cure overnight. Then wash the amine blush off with diluted Simple Green. Sand the epoxy down on the inside and put on a second coat. Let it cure for a minimum of 7 days. Repeat the cleaning and sanding. The epoxy is still curing in that 7 day period. Oil based products will not cure on a surface contaminated with amine blush. You can see this in drawers that have been glued together with epoxy. No one ever cleans the corners well enough. The poly or varnish will stay gummy in the corners for years. Yes, we learned this by fire. Don't get burned yourself. We switched to MAS epoxy because it doesn't have the amine blush problem. Then coat the epoxy with a 2K product such as Bristol Finish, Eurobild, Awlspar, or even an automotive clear coat. Gougon Brothers had a catalyzed varnish. You need a much more durable surface than marine varnish. Sounds like a fun project.

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From the original questioner:
Thanks. What do you think about the bottom, just epoxy it in to a rabbeted bottom and let it be? Just make sure I epoxy all sides to seal it in.

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From contributor A:
Most important part to the whole thing is getting a good bond on the teak. Rough up the surface with 80-100 grit. No shiny parts off the jointer or planer. Definitely seal the entire finished product. I usually use compressed air to blow the dust out of the grain. Then clean the teak with denatured alcohol, acetone or lacquer thinner, before bonding. You could simply clamp the bottom to the sink. No need for a rabbet. However, you could do it for looks and that warm fuzzy feeling of craftsmanship we all strive for.

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From contributor J:
Just a couple of things to consider… Teak is a very oily wood and as such should be washed down before any finish is applied. I am a believer that oils should be removed with petroleum thinners like paint thinner, etc. Here's the problem: Teak oil will wick back up and in this case under any finish/coating that has been applied, delamination will occur. Lastly, I've always been taught to apply the same number of finish coats whether it be the top or bottom (soak all your end grain and cut edges for a good seal also). I think I'd avoid any finish that builds on itself in this application and would tend to lean towards penetrating oils/finishes.