MST Wood Protector

MST Wood Protector is a semi-transparent wood preservative that protects timber rather than covering it, leaving the grain visible. The natural figure and colour of the wood remain on show while the surface is protected against UV, moisture and weathering.

Timber has two great enemies: sun and water. The ultraviolet component of sunlight breaks down lignin, the substance holding the wood structure together; unprotected timber first turns grey, then the surface fibres lift and begin to break away. Water makes the wood move — timber that takes up moisture swells and shrinks again as it dries, and that cycle produces cracking and splitting. A wood protector addresses both mechanisms at once: UV absorbers slow the reaction between light and lignin, while the water-repellent structure limits rain and moisture entering the timber.

Its fundamental difference from an opaque paint is that it does not build a thick, impermeable film on the surface. The protector works by penetrating the pores of the wood and lets the timber breathe. Moisture from beneath is therefore not trapped, and the blistering and flaking seen with opaque paints is largely eliminated. Maintenance is easy for the same reason: renewal does not require stripping the old layer — after cleaning and a light sand, a fresh coat goes straight on.

Typical applications include garden furniture, pergolas and gazebos, timber cladding, fences and railings, external doors and window joinery, terrace and balcony timber, wooden eaves and canopies, and interior decorative timber surfaces.

The timber must be clean, dry and sound. On new wood, sand along the grain, remove the dust with a damp cloth and let it dry. A surface sanded too smooth reduces absorption; a medium grit usually gives a better result.

On weathered grey timber the degraded surface fibres must be sanded back to sound wood. If that layer is left, the protector bonds to broken-down fibre rather than sound timber and lifts within a short time. Mould and algae staining must be treated with a suitable cleaner, then rinsed thoroughly and dried.

Where opaque paint or varnish has been applied previously, the old film must be removed completely; the protector can only work by penetrating the pores of the wood, which is impossible through a sealed surface.

Stir the product thoroughly before use; the colouring pigments settle, and without stirring the tone will drift over the course of the job. If several containers are needed for one job, decanting them into a single vessel and mixing beforehand is recommended for colour consistency.

Apply by brush, along the grain; a brush usually outperforms a roller because it works the product into the pores. End grain, the areas around knots and the joints are where water enters the timber most easily — give them extra attention and apply generously.

Work in thin, even coats. If excess product pools on the surface, the unabsorbed portion stays tacky and picks up dust; brush out any pooling before it dries.

Outdoors two coats are usual; on surfaces exposed to strong sun and rain a third coat extends the protective life. Allow the surface to dry between coats.

With semi-transparent products, colour depth increases with the number of coats. Testing on a small, inconspicuous area first is recommended, since the final colour varies with the timber species.

The maintenance interval depends on exposure; south-facing surfaces taking direct rain need renewal more often. When the time comes, clean the surface, sand lightly and apply a fresh coat directly.

Apply in mild, dry weather and never to a hot surface in direct sunlight. Postpone if rain is expected. Ventilate the area and wear suitable gloves. Collect product-soaked rags in a closed metal container.

The information below describes the general behaviour of semi-transparent wood protectors. For values specific to product, tone and timber species, refer to the technical data sheet (TDS).

Protection has two components. UV absorbers slow the breakdown of lignin by sunlight, delaying greying and surface fibre lift. The water-repellent structure limits rain and moisture entering the timber, reducing the swell–shrink cycle and the cracking that follows from it.

Opaque paint seals the surface and completely changes the appearance of the wood; when moisture is trapped beneath it, blistering and flaking follow, and renewal requires stripping the old film. A protector works by penetration, lets the timber breathe and is far easier to renew. In return, its protective life is shorter than an opaque system and it requires regular maintenance.

It is not sufficient on its own for timber in continuous water contact, in ground contact or buried in the substrate; those conditions require pressure-treated timber. Wood that is structurally rotten or insect-damaged must be repaired first — a protector does not consolidate degraded timber.

Store in the closed original container in a cool, dry place away from direct sunlight. Protect from frost. Pigment settles; stir thoroughly before use.