Thompson's® WaterSeal® Clear Wood Sealer


Thompson’s® WaterSeal® Clear Wood Sealer provides long-lasting exterior wood protection. Clear sealer enhances and maintains the wood’s natural color.

Key Features

  • Exceeds industry standard for ASTM-D4446 for waterproofing wood
  • Crystal-clear sealer and sunblock protects wood and prevents yellowing
  • Helps prevent water damage
  • Provides a mold- and mildew-resistant finish
  • Also available in 5 Gal

Before You Begin

  • For exterior use only.
  • For wood substrates only.
  • Allow 30 days before applying on new pressure treated lumber.
  • Be sure that both surface and air temperature are above 50˚F during application and for 48 hours after application. Do not apply product if rain is forecasted within 24 hours of application.
  • Perform the splash test. Sprinkle water on various sections of surface to be sealed. If water absorbs and darkens color of surface within five seconds, surface is porous and considered ready to be treated. If water beads up or otherwise sits on top of surface, then surface does not need protection at this time.
  • Cover plants and shrubs. Move all objects that could come in contact with overspray. Overspray of product onto glass should be removed immediately with paint thinner or mineral spirits, following manufacturer’s safety recommendations.
  • Do not use in below grade application where water pressure is a problem or on painted or recently stained surfaces
  • Do not freeze. Do not store below 32˚F
  • Excessive oiliness caused by over application may be removed by scrubbing wood with concentrated degreaser.

Surface Preparation

  • WARNING! Removal of old paint by sanding, scraping or other means may generate dust or fumes that contain lead. Exposure to lead dust or fumes may cause brain damage or other adverse health effects, especially in children or pregnant women. Controlling exposure to lead or other hazardous substances requires the use of proper protective equipment, such as a properly fitted respirator (NIOSH approved) and proper containment and cleanup. For more information, call the National Lead Information Center at 1-800-424-LEAD (in US) or contact your local health authority.
  • Surfaces and substrates must be free of all mildew stains, dust, dirt, oil, soot, grease and other contaminants.
  • Surfaces must be thoroughly cleaned prior to application with a deck cleaner (like those in the Thompson’s® WaterSeal® cleaner line) applied according to label directions and cautions.
  • Remove all existing loose, flaking or peeling stain. Failure to do so will result in continued flaking and peeling.
  • If surface is damp or wet from cleaning or weather, allow the surface to dry thoroughly (a minimum of 48 hours) before application.


  • Do not mix with other waterproofing products; variations in the final appearance of the surface being treated may result.
  • Do not thin.
  • Shake contents well before use. Shake or mix thoroughly before and occasionally during use.
  • A small trial patch should be tried before application over the entire surface.
  • Only one light coat is necessary in most applications.
  • Apply by brush, roller, dipping, or sprayer. A garden “pump-up” style sprayer is the simplest method. If over applied, remove excess before it dries by redistributing to dry areas or wiping off.
  • Use only with adequate ventilation.
  • Oiliness and tackiness will result if over-applied, applied to wet or damp surface, or if overnight temperature falls below 50˚F within 48 hours of application.


  • Allow at least 48 hours to dry; however drying time will vary depending on the substrate, temperature, and humidity.
  • Allow minimum of 30 days drying time before applying oil based paint over Thompson’s® WaterSeal® Waterproofing Wood Sealer – Clear. Do not apply latex based paint over Thompson’s® WaterSeal® Waterproofing Wood Sealer – Clear.
  • Length of protection will vary depending on environment. Perform the splash test once a year to see whether reapplication is necessary. For maximum protection from color change and other damage caused by the sun, reapplication is recommended every year. Vertical and horizontal surfaces will experience color changes at different rates.

Clean Up

  • Clean brushes and equipment with mineral spirits following manufacturer’s safety recommendations, then rinse with clean water.


CAUTIONS: CONTAINS MINERAL OIL. Contents are COMBUSTIBLE. Keep away from heat and open flame. VAPOR HARMFUL. Use only with adequate ventilation. For Exterior Use Only. To avoid overexposure, if treating enclosed exterior rooms or porches, open windows and doors or use other means to ensure fresh air during application and drying. If you experience eye watering, headaches, or dizziness, increase fresh air, or wear respiratory protection (NIOSH approved) or leave the area. Avoid contact with eyes and skin. Causes eye, skin and respiratory tract irritation. Wash hands after using. Keep container closed when not in use. Do not transfer contents to other containers for storage. FIRST AID: In case of eye contact, flush thoroughly with large amounts of water for 15 minutes and get medical attention. For skin contact, wash thoroughly with soap and water. In case of respiratory difficulty, provide fresh air and call physician. If swallowed, call Poison Control Center, hospital emergency room, or physician immediately. DELAYED EFFECTS FROM LONG TERM OVEREXPOSURE. Contains solvents which can cause permanent brain and nervous system damage. Intentional misuse by deliberately concentrating and inhaling the contents can be harmful or fatal. WARNING: This product contains chemicals known to the state of California to cause cancer and birth defects or other reproductive harm. DO NOT TAKE INTERNALLY. KEEP OUT OF THE REACH OF CHILDREN.

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