Furniture, Wood and Cabinetry Finishing - Paint versus Thompson's on hurricane shutters

I'm building a set of plywood hurricane shutters. They'd be put into place over the windows. It's CDX. It's not pressure-treated. It's sanded on the one side.

I got the idea from here:

http://www.aoml.noaa.gov/hrd/shutters/index2.html

I'm trying to decide if I'm beter off painting them or using something like thompson's water seal? When in place, they'll be exposed to brutal weather obviously. When the shutters are not in place, I plan on storing them outside under a tarp on top of some bricks.

I only care to do this job once. Which is going to last longer?

Paint will always last longer than water seal.

I used $1.00 a gal "ooops ' Paint on mine

CDX is usually not sanded on any side. But that aside, I would treat it with a wood preservative like Cuprinol(if available) or other copper based chemicals. Thompsons is a waste of money, even according to Consumers. Be sure to seal all sides, including the edges.

I'd go with a solid body stain. I agree on not using Thompson's.