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NANO Penetrating Wood Sealer

Long-lasting, Eco-Friendly Wood Protector & Stain

4.50 out of 5based on 14 customer ratings
14 customer reviews


  • Fences
  • Wood Siding
  • Log Homes
  • Cedar Shingles
  • Exposed Beams
  • Outdoor Furniture
  • Play Structures
  • Planters & Plywood
  • Woodworking
  • Window & Doors


  • Water-based, Ultra-Low VOC
  • Eco-friendly, Non-toxic, No Odor
  • Won't harm people, pets or plants
  • Penetrates below the surface
  • Creates flexible, breathable barrier
  • Prevents mold, mildew & wood rot
  • Stabilizes wood from warping
  • UV barrier protects from sun rays
  • Extends natural life of wood
  • Easy soap & water clean-up

SEAL-ONCE® has been leading the innovation in the use of nanotechnology to create long-lasting, Eco-friendly wood sealers & tinted wood stains since 2005.  Our New & Improved NANO Penetrating Wood Sealer, deeply penetrates the surface of wood to protect and stabilize against water damage and decay.  Unlike many top-coat sealers that trap moisture below the surface, NANO creates a long-lasting, flexible, breathable barrier, that allows water vapor to escape & prevent damage.  NANO is warranted to prevent water intrusion for up to 10 years on horizontal & 6 years on vertical surfaces.

SEAL-ONCE® NANO Waterproofing Wood Sealer & Stain is ideal for use on unfinished interior and exterior wood surfaces. The clear, non-film forming formula allows the wood to age naturally without decay, morphing to a rich silver-gray over time. It can also be used as a wood stain, when mixed with a full range of semi-transparent tints to enhance the appearance & provide additional UV protection from sun rays.  When using SEAL-ONCE NANO as a pre-stain or sanding sealer, the clear formula allows for a smoother finish, more even color and easier application of water & solvent based stains or finishes. It also enhances the natural grain of the wood.

Product Details

  • All surfaces should be cleaned before sealing for best penetration and performance.
  • Remove all old coatings, dust, debris and loose material. Remove oil, grease, algae, grime, mill glaze and mold and mildew stains with appropriate cleaners. Recommend SEAL-ONCE All Wood Cleaner.
  • Test absorbency after cleaning by sprinkling water on surface. If the water does not readily penetrate the surface, stripping will be necessary to remove old coatings.


  • Do not use if air or surface temperature is below 45°F/7.22°C or above 95°F/35°C.
  • Do not apply in rain or when rain is expected within 12-24 hours.
  • DO NOT THIN. Mix well. Stir contents or shake thoroughly prior to use.
  • Test a small area to ensure acceptable appearance and penetration.
  • Apply first coat with a synthetic brush; pump-up garden sprayer; air-assisted and/or airless sprayer. Use 15-17 tip and medium to coarse spray pattern. When spraying, always back brush for best results.
  • Second coat can be applied once first coat has penetrated but is still damp. Second coat must be applied within one hour of applying first coat.
  • For best results, apply in the shade and out of direct sunlight.
  • When applying in direct sunlight and wood surface is hot, spray with a mist of water and apply SEAL-ONCE NANO immediately on dampened surface.
  • Apply to all surfaces. Apply SEAL ENDS ONCE® to wood ends.
  • Do not use with other waterproofing products.
  • Wood can be painted or stained as soon as it dries in approximately 2-3 hours, if SEAL-ONCE Semi-Transparent Tints are not being used.
  • Allow approximately 2-3 hours for surface to dry, depending on temperature and humidity.
  • Allow 12-24 hours for full cure, depending on temperature and humidity.
  • When recoating, apply as soon as previous coat has penetrated and surface is damp, not wet. Second coat must be applied within one hour of applying the first coat.
  • Clean all application with warm soapy water.
  • Disposal: soap and water cleanup; no special disposal procedure needed.
  • Store unused product above 32°F/0°C to protect from freezing.
  • Shelf life (unopened): 3 years


  • Surfaces that have been treated with SEAL-ONCE NANO Penetrating Wood Sealer can be cleaned using a mixture of 1-gallon warm water, 14 oz. bleach, and 1 oz. of Dawn® dish detergent. Apply this cleaning solution with a sprayer and allow to sit for 20 to 30 minutes on the wood surface before rinsing with water using a garden hose with a nozzle.
  • This cleaning solution can be used to remove airborne mold and mildew stains, dirt and grime from the wood surface. SEAL-ONCE NANO will prevent and resist any water, mold and mildew penetration. Do not use oxidizers, corrosives, or strippers on surfaces that have been treated with SEAL-ONCE NANO.
  • Surfaces can be recoated with SEAL-ONCE NANO at any time. SEAL-ONCE NANO may need to be reapplied for fading tint color, surface damage, in heavily worn or high traffic areas, or in places where the surface may have undergone noticeable changes.
  • Before reapplying SEAL-ONCE NANO, clean the surface using the recommended cleaning solution above. Apply SEAL-ONCE NANO according to package instructions. When reapplying in small areas, lightly overlap onto areas previously treated with SEAL-ONCE NANO.

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