SEAL-ONCE MARINE - 1 Gallon Penetrating Wood Sealer, Waterproofer & Stain. Water-Based, Ultra-low VOC formula for high-moisture areas to protect wood docks, decks, piers & retaining walls. is a Paint Wall Treatments & Supplies option for everyday use, business supply needs, resale shelves, or household stocking. Review product size, pack count, and shipping details before checkout.