Why paint exterior wood?
Why bother painting exterior wood? Some people do it for protection, others do it for style. But the end result is the same. Provided you do the preparation properly you’ll achieve a beautiful, durable finish that’ll last for ages and protect the wood from the worst of the British weather’s ravages.
What is the definition of paint?
The dictionary definition of paint is “a coloured substance which is spread over a surface and dries to leave a thin decorative or protective coating.” Many people just want colour, and they assume paint is the only option. If that’s you, you’re in for a nice surprise. Coloured wood stains can deliver an equally attractive effect, although they tend to be translucent, and they protect exterior wood better than paint.
How to prepare exterior wood for paint
Every wood maintenance project begins the same way – you need to make sure the surface is sound, clean, dry, free from dirt, dust and grease. It’s also a good idea to fill cracks, holes and open joints with a good exterior filler, so you get a smooth, even, professional-looking finish.
Preparing bare wood for paint
- Give the surface a sand to provide a ‘key’ for the paint to stick to
- Brush and dust the surface afterwards to get rid of every spot of sawdust
- If the wood is showing signs of fungus or mildew, treat the surface with an anti-fungal exterior wood treatment, followed by a non wax or oil-based preservative before you prime it
- Rotten wood needs to be cut out, including at least 25mm of good wood around the rot and replaced with new wood
- If the wood is knotty, you’ll need to cover the knots with a good wood knot and resin blocker or the knots will cause stains that show through the paint. If not, an ordinary primer or undercoat should do the trick. Having said that, some wood paints don’t require an undercoat, so check first
- Now you’re ready to apply a topcoat of coloured paint. Just make sure you leave adequate time for any undercoat or primer to fully dry first
- You might need two top coats – it depends on how the wood looks after one coat, and what the manufacturer’s instructions say
Preparing exterior wood that’s already been painted
- Again, your first task is to get busy with the sandpaper, getting rid of loose paint that has flaked, peeled and blistered to reveal a flat, smooth surface with a good key
- Use a mould remover if there’s any wood rotting fungus in evidence or the wood is in a particularly damp area and might need extra protection
- As before, cover any knots with a special knot and resin blocker, otherwise use an ordinary primer or undercoat
- Leave your undercoat/s to dry completely then add your topcoat
What if you want a translucent finish?
Paint isn’t the only product for fabulous-looking exterior wood. You might not want an opaque finish, which covers the wood completely and blocks its natural colour. What if you prefer a translucent finish, where the beauty of the wood’s grain and glowing hue shines through?
If that’s what you’re after, wood oils, wood preservers and wood stains might be just the thing. Unlike exterior paints they won’t flake, crack or peel. And also unlike paint, they have a useful extra function: they nourish the wood and keep it supple, which in turn makes for a longer life.
How to prepare exterior wood for an oil-based wood stain
- Sand the timber back to bare wood and dust the surface
- Use a good quality brush to apply the stain
- Work in small sections so you keep control of the job – try to cover too much of the surface at once and you risk runs, overly-thick or thin areas and sticky bits
- Always brush in the direction of the wood grain
- Follow the manufacturer’s instructions about the number of coats – many wood oils require at least two coats, some more
- Let the product dry fully before adding the next coat
- Sand the surface down with 240 grade sandpaper before you add the final coat for an extra-smooth and longer-lasting finish
Preparing exterior wood for a wood preserver
- Remove any existing surface coats of varnish, paint or other surface coatings by sanding or with a suitable stripping or removing product
- Make sure the wood is clean, dry and dust-free
- Apply the wood preservative with a brush or paint roller – if the surface area is large you might want to invest in a spray system and save yourself a lot of time
- Let the product dry fully in between coats, and follow the manufacturer’s guidelines about how many coats you need
How to prepare exterior wood for a wood oil
Wood oils deliver a water-repellent finish and enhance the wood’s natural colour. They also feed, seal, nourish and protect it. Some oils deliver a very hard wearing surface, for example decking oils, others give protection against damaging UV rays. Many do both to some degree or another. Colourless or clear wood oils may offer some UV resistance but it’ll never be as much as a coloured wood oil or oil-based wood stain. As a general rule, the darker the colour, the more UV resistance the product offers.
- If the wood is new, sand and dust it first to create a smooth surface
- Many wood oils can be applied to a previously-oiled surface, but always do a test area first
- If the wood has already been varnished, painted or stained with some sort of surface coating, you’ll need to remove the original finish first with a suitable stripper or by sanding
- If the wood has gone grey through weather-wear and UV rays, you’ll need to sand it back first to reveal the natural colour
- Never apply wood oil to a damp surface or in direct sunlight
- Apply the wood oil according to the manufacturer’s instructions – they’re all slightly different
Colouring exterior wood – Your front door and window frames
Why? Apart from being traditional, it’s an aesthetic thing. Top quality old or new solid oak doors and lovely, old, distressed vintage doors can look fantastic unpainted, simply preserved and sealed.
If you want to varnish or oil your exterior wood doors and window frames, follow the same instructions as you would for a wooden fence or shed for a beautiful, rich, natural wood look.
- If the paint is flaking and obviously on its last legs, strip it off and start again using a good quality primer, two undercoat and usually 2 or more coats of gloss
- If the paintwork isn’t in too much of a state you can rub it down with wet and dry sandpaper to create a smooth surface then add two undercoat layers and one or 2 coats of gloss or, if you don’t want that super-shiny look, a matt or silk-finish exterior paint
Exterior wood finish health and safety tips
Some wood maintenance products are solvent-based, which means there are a few essential safety tips to take into account. If you don’t know, read the label. Here are some common sense health and safety tips which are useful whatever product you end up using.
- Check for any product-specific safety tips on the tin or container
- Only use solvent-based wood products in well ventilated areas
- Either wash or throw away any rags, cloths or brushes you’ve used – in some circumstances solvent-soaked items can catch fire
- Wear protective clothing and gloves if the manufacturer recommends it
- If you get any product in your eyes or on your skin, wash it off straight away – better safe than sorry
- Keep wood finishing products away from food, areas where food is prepared, children and pets. If you’re working near a water tank or pond make sure you keep the product away from the water – many wood maintenance products can be harmful to plants, people, animals, insects and especially fish when the product is in liquid form. When dry, they’re generally perfectly safe for people, plants and animals
- It’s wise to keep the product in the container it came in and keep it tightly closed when you’re not actively using it
- Avoid breathing in any fumes
- Steer clear of naked flames, including cigarettes and lighters – some products are highly flammable, especially before they’re dry
- Always dispose of any unwanted product responsibly – find out how on your local council website
- If anyone accidentally ingests any of the product, get to a doctor straight away and take the product label with you so medical staff know exactly what’s been consumed
- Don’t spill products on plastic, concrete, bricks or anything else, since it might stain or otherwise damage them
Any questions about wood paint, oil, preserver or varnish?
Unlike many online suppliers, we’re more than happy to give you advice, help and support with choosing the right product or products for the job. Call us for friendly, expert advice.