1 LTR Polyvine Exterior Wood Varnish
EXTERIOR WOOD VARNISH
A waterproof, microporous, UV resistant clear protection for exterior wood. The unique polymer system gives a silky satin finish and highlights the natural grain of the wood. It is suitable for exterior softwood and hardwood
timber applications, giving a high level of UV resistance, waterproofing and preservation.
A clear acrylic hybrid coating specially formulated to protect exterior wood against ultraviolet light and rain damage, with a durable satin finish.
Water-resistant, stain-resistant, heat resistant, and vapour permeable.
Available in satin and dead flat. To achieve a dead flat finish, apply 3 coats of satin before a final coat of dead flat.
Ensure the surface to be coated is clean and free from grease, wax or polish
Exterior timber surfaces should always have a 9-degree slope to allow water to flow away and not gather in joints.
This helps to prevent water from gathering on horizontal surfaces
It is important oil is removed from the surface prior to coating (oily timbers e.g., Teak, Iroko, Rosewood, otherwise that could cause a problem with adhesion, so put some methylated spirits onto a cloth and then give the surface a good wipe down. The important thing is to rotate the cloth around. Polyvine does not recommend using white spirit, when using water-based systems, it can leave a greasy residue on timber, so methylated spirits is better.
For very oily, durable timbers like Iroko cellulose thinners may be necessary.
General details for preparation of surfaces
New wood should be allowed to dry thoroughly before assembly begins. If the wood is green or has been pressure
treated allow to dry before coating (below 18% moisture content).
New and weathered wood
New wood can be contaminated during preparation, or in the machine shop. Weathered wood can already have contaminants on the surface.
All contaminants and millwork must be removed from the surface by sanding, 80/120 grit for vertical, 60/80 grit for horizontal surfaces.
Fungus, pollen or spores not removed and trapped below the clear varnish will discolour the surface of the timber when exposed to moisture. If contamination is suspected treat timber with a proprietary preservative treatment as recommended by the manufacturer.
Previously painted wood
Completely remove old coating with 60/80 grit sandpaper.
Ensure surface is dry clean and free from dust, follow new and weathered wood instructions.
Fill all joints, Cracks, and nail holes with a good quality Polyurethane or acrylic filler prior to coating.
Apply Exterior Wood Varnish liberally with a good quality synthetic brush, apply in the direction of the grain, maintain a wet coat.
Allow 4 hrs between coats
Best application temperature 10C/50F to 30C/90F. Do not apply in direct sunlight or when rain is imminent.
Saturate all end grains.
Exterior Wood Clear Coat contains a sophisticated UV filter system, this system will protect to the maximum when the dry film thickness reaches 100 microns. 3 generous coats / 4 standard coats.
Windows, doors and exterior furniture, contain a lot of joints and end grain, to ensure maximum life and to avoid coating delamination, the following procedures should be carried out.
Coat on all surfaces, inside and outside and all edges. Holes, joints and end grain, saturate liberally with the clear coat, fill with good quality filler as required.
Always apply to a test area before starting work. Care must be taken when applying in high temperature or direct sunlight as this will affect drying time. Do not apply when rain is imminent. Coating life will be reduced on
horizontal surfaces and where the coating is in contact with the ground or pooled water
The open grain texture of Oak will cause film failure.
Varnishes are prone to failure when applied to Oak externally.
It is imperative therefore that the grain is filled with coating before further coats are applied.
Oak is not as resistant to weathering as oily hardwoods and, therefore, needs better protection when used outdoors. The large open pores make the problem worse providing a route for water-ingress. Blue-stain mould
spores are likely to be present on any piece of timber and will be activated by moisture. Another problem with Oak is the high tannin content, if not properly sealed water (rain) can wash the tannin out of the wood leaving a patchy
colour and staining to the surrounding areas (bricks, patio, etc.).
Pre-conditioning to the correct moisture content is very important. If the Oak is outside the moisture content range of 12-20% there will be excessive movement as it comes to equilibrium. The wood can become split, and the
coating film may also split exposing bare wood, providing a route for water-ingress and rapid deterioration of the coating.
If this occurs remedial action must be taken immediately to prevent the wood becoming weather-stained. Clean the surface and reapply sufficient coats of the same coating product to fill the cracks/splits.
The coating integrity cannot be guaranteed on green oak.
Protection of Oak
Polyvine Recommend Exterior Interior Wood Oil.
Often known as ‘African Teak’, Iroko is a West African timber.
It shares many of the same great characteristics of oak and teak which makes it a popular alternative to those woods. It’s naturally resistant to decay over time and the ravages of insects – meaning that it lasts longer than
other woods with little maintenance needed.
The heartwood is golden-orange to brown in colour. Lighter vessel lines are conspicuous on flat sawn surfaces.
Large deposits of calcium carbonate, with darker coloured surrounding material are usually present. Yellow bands of soft tissue are reported to form a zig-zag pattern on all surfaces.
Iroko has a medium to coarse texture, with open pores and an interlocking grain.
Endgrain. Diffuse and porous; large to very large pores.
A wood that is sometimes resistant to wood finishing products. Iroko contains a non-saturated phenolic compound, which is a powerful anti-oxidant. It is necessary to use oil varnishes without free siccative oils.
Oils in the surface of the timber must always be removed before coating application.
As you know Iroko is a timber that moves with temperature fluctuations.
Protection of Iroko
Polyvine Recommend Exterior Interior Wood Oil.
Intense exposure to sunlight will cause gradual fading of the timber colour. A pretreatment of Polyvine Wood
Colour is recommended in these areas to enhance the timber colour and prevent fading.
Application to softwood, knots and resin pockets will bleed through the coating.
Inspect yearly for signs of wear or damage.
Clean surface thoroughly and wash of all cleaning solution.
A maintenance coat should be applied every 1 / 3 years on exposed areas, 3 / 4 years on less exposed or sheltered areas.
Approx. 10-20 sq. m per litre.
Any equipment used can be cleaned using soap and water before the clear coat dries. Wipe any excess off surfaces with a damp cloth. Any dried deposits will need a paint stripper to remove them.