To Paint or Not to Paint – Colouring Exterior Wood


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

Very few people tend to use oils and varnishes on their front door. Natural wood looks lovely, of course, but doors and window frames are usually painted.

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.


  1. Hi there,

    Need to some advice. We have recently had our garden landscaped and want to paint our fences a dark grey to match the updated look. The fence was coated Roxil wood protection cream last summer which has water proofed it. Can we actually paint over this with a suitable fence paint? Or use a coloured wood preserver. It would be really helpful to know what options we have to try to and do this or if it’s a lost cause.

    Thanks in advance for your help!

    • Good Morning,

      Thank you for your enquiry. We will need to ask you a few more questions regarding the Roxil before we can recommend a compatible product. Please contact us at your convenience

  2. Why does the wood knots still visible even after I have treated them, I have put clear varnish on but can still see knotts, what else can I use ie what varnish please

    • Good Afternoon Rose,

      Any clear product applied to wood, will allow you to see all the detail if the piece, grain pattern, knots and any other marks on the wood. You can not hide knots unless you apply an opaque (solid colour) the the surface.

      If you would like to get in touch with details of you project and what you are hoping to achieve, I will be happy to take a look and see what I can recommend for you. Can you include details of wood type, project type, interior or exterior and what look you want o achieve?

      And I will narrow down some options for you to consider >>> contact us page.

      Kind regards Samantha.

  3. Hi, I have moved home and the garage has a stained timber front , its very old scruffy and has a reddish look. I wanted to stain over it with a dark colour but the stuff Ive bought runs off and doesnt seep in . Can I buy a product that will paint over without having to, sand right back to bare wood, its not worth that but I cant afford new frontage, Im a 61 year old lady on my own and couldnt tackle a big sanding project, thanks

    • Good Morning Claire,

      Thank you for getting in touch with your question, it sounds like what ever is currently applied is repelling what you are trying to apply, it is in effect doing its job.

      If you could get in touch with me via our contact us page with some photos and the details of the product you are trying to apply and perhaps I will be able to help further.

      kind regards Samantha.

  4. Hi. I’m currently building a summer house (5×2.5×2.5). The outside is going to be clad with planed T&G timber – NOT treated.
    Could you recommend a wood preserver that I can apply to both sides of the cladding & sawn ends before I fit it to the summer house. I’m looking for a wood preserver that will offer great protection but also allows me the option of painting over it.
    Any ideas?

    • Good Afternoon Richard,

      I can recommend the Barrettine Premier Universal this is a good quality preservative that does not contain wax and so will allow you to use a paint over the top.

      For the rough ends I can recommend soaking in the preservative for a short while allowing the wood to soak up as much as possible or you could look at the Ronseal Decking End Grain Protector as another good option.

      If you take a look at these products and feel free to get back to me if you have any further questions.

      Kind regards Samantha.

  5. Two parts to my question. I have recently purchased an old half timbered house that had render on the outside. The frame is good in parts and not in others. I am going to remove the render and lightly clean off the external surface with a very light sand blasting. Should I then leave the oak untreated or does it NEED something to protect it ?
    Secondly – There are new oak windows and internal doors. What to do with internal oak, especially the doors to seal them from grubby fingers etc. And what to do with the window frame externally and does the rebate need something special for the glazing mastic to bed on?
    Many thanks for the information on your pages.

    • Hello David,

      Thank you for your inquiry. The first product I would recommend would be a good quality Preservative. This will protect from mould, mildew and rot and should be applied to the wood first. Test areas should be done to ensure there is nothing on the wood preventing penetration. The Preservative can also be used on the exterior of the window frames if necessary.

      Many people use this as a stand alone product but we do recommend a top coat for the best protection and an oil such as decking oil or the Osmo UV Protection Oil Extra. Test areas should be done to ensure that there is nothing to prevent penetration and that you are going to get the finish that you want.

      For the interior areas that need treating I would recommend the Osmo Polyx Oil. It will protect the wood and is easy to maintain and apply. It will darken the wood slightly to give the ‘wet look’. It’s worth having a look at our YouTube Channel as well for some helpful product advice and application tips. If you have any further questions I am always happy to help.

      Kind Regards Sam.

  6. Hello,
    I’ve bought a wooden playhouse for my garden. It’s had a water-based treatment applied in the factory, but needs a “spirit-based wood treatment”. Once protected, I want to paint the playhouse blue and white.
    Could you let me know please:
    1. what external wood preservative/protector should I use?
    2. what paint I can then cover it with?
    3. should I re-apply the preservative annually?
    Many thanks for your help,

    • Hello Fiona,

      Thank you for your inquiry, for the best finish and protection I can recommend Barrettine Premier Wood Preservative which comes in a clear finish and then you could look at the Osmo Country Colours which is a protective Oil that soaks into the surface of the wood but gives a paint like affect.

      The benefit of this is that it will not peel or flake over time like paints will. Two thin coats are all that is required and this will protect for 1 or 2 years (depending on weather and sunlight) before needing a top up coat. The preservative will not need topping up for at least 6- 8 years if the Oil is well maintained.

      As an alternative you could look at the Universal Preservative and then the Ronseal Garden Paint which will again protect for 1-3 years depending on weather and then will need removing before retreating.

      I hope that helps and if you have any further questions please don’t hesitate to get in touch.

      All the Best Sam


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