Wood Sealer

A quality waterproof wood sealer applied to clean, sound timber is the single most effective preventative treatment available.

GK Invisible Wood Sealer is our professional-grade waterproofing sealant for wood, developed for use on decking, fencing, garden structures, and all outdoor timber surfaces. It delivers deep-penetrating moisture protection with a completely invisible finish, meaning the wood's natural appearance is fully preserved after treatment. No tint, no sheen, no change to the surface. Just long-lasting waterproof protection working from within the wood.

How GK Invisible Wood Sealer Works

Unlike surface-coating products that sit on top of the wood as a film, GK Invisible Wood Sealer is a penetrating waterproof wood treatment. It absorbs into the timber's porous structure and creates a moisture-repelling barrier from within, causing water to bead and run off the surface rather than soaking in.

This penetrating action is what makes it significantly more durable than film-forming alternatives, which can crack, peel, and allow moisture to enter once the surface layer is damaged.

The product is water-based and ready to use straight from the bottle, requiring no dilution, no mixing, and no specialist equipment. Apply with a brush, long-pile roller, or low-pressure sprayer to a clean, dry surface. Two wet-on-wet coats are recommended for best results, with the second coat applied before the first has dried to maximise penetration depth. Touch dry within two hours, fully dry and trafficable within 24 hours.

One 5-litre bottle covers up to 25 square metres, sufficient for a substantial section of fencing, a medium-sized decking area, or multiple garden structures in a single treatment session.

The Invisible Advantage: Waterproofing Wood Without Changing Its Appearance

For many customers, the defining appeal of GK Invisible Wood Sealer is what it doesn't do. Unlike decking oils and stains that alter the tone and finish of the timber, this waterproof wood sealant is invisible once absorbed. The wood goes back to its original appearance with no darkening, no sheen, and no surface film.

This makes it the ideal waterproof wood sealer for customers who want to protect the natural colour of their timber without committing to a stained or oiled finish, and for surfaces where a natural look is important: untreated oak fencing, silver-grey hardwood furniture, natural timber cladding, or freshly laid decking.

The formula also incorporates an algae-repelling action, meaning treated surfaces are resistant to the biological growth that accumulates on untreated outdoor timber in the UK climate. This dual waterproofing and algae-inhibiting performance makes it a more complete wood waterproofing treatment than a simple moisture barrier alone.

What GK Invisible Wood Sealer Can Be Used On

Our waterproof wood treatment is suitable for a wide range of outdoor timber applications, including:

• Decking: all softwood and hardwood decking surfaces. The sealed surface does not increase slip risk, making it safe for use on decking areas. Allow 24 hours before returning to heavy foot traffic after application.
• Fencing: one of the most cost-effective timber fence treatments available, protecting panels, posts, and rails against moisture ingress and biological growth.
• Garden structures: pergolas, arches, raised beds, garden furniture, planters, and any outdoor timber structure exposed to the elements.
• Cladding and external joinery: window frames, door frames, and timber cladding boards can all be treated to reduce moisture ingress. Not intended as a substitute for paint or stain on painted joinery.
• Outbuildings and sheds: treat external timber to extend the life of the structure and reduce the frequency of maintenance.
• Bird boxes and garden accessories: GK Invisible Wood Sealer is safe for use on the external surfaces of bird boxes, with the entrance hole and interior perches left untreated.

Waterproofing Wood: When and How Often to Treat

For new or freshly cleaned timber, apply GK Invisible Wood Sealer as soon as the surface is dry and the wood is clean. Always clean and prepare the surface before applying any waterproofing sealant for wood, as treating over dirt, algae, or weathered grey timber reduces penetration and shortens the life of the treatment.

Our GK Wood Restorer is the recommended preparation product for weathered or greyed timber ahead of sealing.

For maintenance, the simplest test is the water bead test: splash water on the surface. If it beads and runs off, the existing treatment is still performing. If the water soaks in, it's time to retreat. For most outdoor timber in the UK, re-treatment once a year keeps moisture protection consistently effective. Surfaces in particularly exposed locations such as full sun, coastal areas, or heavy rainfall regions may benefit from treatment every six to twelve months.

Questions about the right product for your timber type or project? Call us on 07557 111 297 or email sales@gkproductsuk.com. Free delivery on orders over £60 to mainland England, Wales and parts of Scotland.