A.Bill Feist, a former wood-finishes researcher with the Forest Products Laboratory in Madison, Wis., and co-author of Finishes for Exterior Wood, responds: To protect the fir flooring over the winter, your best choice would be to use a paintable water-repellent preservative (WRP) like Behr's No. 2-85 Multi-Purpose Waterproofing Sealer (800/854-0133, extension 2; www.behr.com); Wolman's Woodlife Classic Clear Wood Preservative (800/556-7737, www.wolman.com); or Cuprinol's Clear Deck & Wood Seal (800/424-5837, www.cuprinol.com).
There are a variety of WRPs on the market. Many of them are formulated for use as natural finishes on decks and fences, but these are not paintable and could cause paint-adhesion problems like blistering or peeling later on. So it's very important that the treatment you choose be described as paintable by the manufacturer.
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