I agree with using an oil based finish. Some woods like cedar, and if I
am not mistaken, cypress would be similar to cedar, contain natural oils
in them that can cause urathane finishes to peel away. There are several
good oil finishes that have UV protection in them, which is all you
really need for cypress since it will hold up just fine on it's own to
the elements. Sikens (sp?) and cabot both make high quality products.
Also try Penofin.

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