Without adequate protection, your home wooden chairs, stools, patio furniture or modern restaurant tables, restaurant table tops or commercial dining tables etc., will eventually deteriorate – especially if they are used outdoors.
Wood is a great natural material with unique characteristics that make it – especially hardwoods like balau, teak, and meranti – suitable for a variety of exterior applications. But without adequate protection from the sun and moisture, it will eventually deteriorate. Here’s how, when and why to protect it.
Can I treat weathered wood?
If left untreated and allowed to weather, hardwoods will turn a light silvery-grey color over time. As they contain natural oils in these woods, they do not generally need extra treatment and are therefore ideal for outdoor use. However, they can benefit from certain treatments to preserve their natural color. This can either be water- or oil-based product that soaks in and feeds the wood, but doesn’t leave a surface coating like varnish or paint. Weathered wood generally needs to be sanded before treatment to remove the old ‘dead’ top layer. However, new products on the market make life easier as they are designed to remove this grey layer by scrubbing alone!
Why varnish or treat wood?
Wood basically starts to dry out and decompose as soon as a tree is cut down and turned into lumber. As the natural oils and moisture in wood are released it becomes dry and brittle. Exposure to the sun will dry the wood, shrinking it – while constant exposure to UV rays will dull the surface. Continuous wet and dry cycles (both seasonal and from day to night) cause wood to swell and shrink, warp, split and crack – all of which lead to premature deterioration.
With the old ‘dead’ layer removed, this planter looks good as new. Resealing the cleaned surface will protect it and bring it back to life.
TIP: If you prefer the silvery weathered look, keep moisture out by applying a sealer once the wood has aged to the desired color.
What products do I use?
Wood treatment products generally fall into two categories: the first forms a film or coating on the wood surface and the second penetrates it. Understanding the differences between them will make it easier to select the right product.
Filming products (similar to solvent-based or water-based varnish finishes) provide a barrier between wood and the elements. Depending on its formulation, these can leave a gloss, semi-gloss or satin finish. But they can be subject to flaking and cracking over time. A film finish is susceptible to cracking when the wood expands and contracts or when water gets underneath the finish and deteriorates the wood – although some newer water-based coatings have excellent flexibility and better penetration. TIP Generally, film-forming finishes are not recommended for decks. Try wood sealers or oils instead. Products with tints (some varnishes such as meranti, teak, and oak are tinted) offer more protection from UV radiation than clear options.
Penetrating wood finishes (oil or water-based products) saturate wood pores to prevent water penetration. New water-based products offer excellent penetration and perform as well as or better than oil-based products. Penetrating finishes provide longterm water repellence and unlike film forming products, they don’t trap moisture in the wood nor do they peel and blister. Better still, reapplying these products as part of your regular maintenance program is easier as little or no preparation is needed.
Decking planks often have grooves that are more easily cleaned by using a wire brush and steel wool in preparation for treatment. Once the surface debris has been removed the piece can be sealed. Sealers biodegrade at the end of their lifecycle – they don’t crack or flake – making them more suitable for decks, especially those with grooved planks.
Together with turpentine, steel wool can be applied to clean wood or to remove leftover varnish. If steel wool doesn’t completely remove residual spots of varnish, try sandpaper, but be careful not to leave depressions in the wood surface. TIP Dip some medium-fine steelwool in paint remover to scrub away any remaining finish. When reapplying wood oil, all you need to do is rub down the surface with steel wool.
Technological advances and laws on emission levels of volatile organic compounds (VOCs) have spurred the development of new eco-friendly products.
Nature-based products EnviroTouch produces a range of 100% natural finishes specially made for the treatment, protection, and maintenance of all wood surfaces. ProNature products use only natural ingredients such as beeswax, plant oils and extracts and don’t contain any additives that cause harmful emissions.
Harlequin’s Exterior Varnish is a low odor, water-based finish that can be applied over any raw or previously varnished (but not oil-based) surface. It allows for natural movement of the wood and has excellent UV-stability due to a specialized ultraviolet absorber. It’s available in a satin sheen finish and six colors. Water-based varnishes are better for the environment, don’t yellow and make cleaning brushes much easier. Dulux Woodgard Water Clean-up allows for easier cleaning of brushes and rollers. Advancement in formulations has to lead to environment-friendly (and human-friendly!) water-based ranges such as the removal range from Plascon, which includes paint removers. This weathered wood restorer easily removes that dull grey layer from weathered wood.
Did you know?
Drying times for natural varnish averages 24 hours, but water-based varnish and polyurethanes often dry more quickly. REMEMBER to Look for products that offer good water repellency and protect the wood from UV rays.
Proper preparation is key
The key to an excellent finish lies in the preparation of the wood surface. The better the surface is prepared, the easier it is to achieve that sought-after finish. First, you have to remove debris and thoroughly clean the surface before sanding down and finally, sealing.
1. Get it clean
There are various paint stripping products and techniques available, so make sure you choose what works best for you and the wood.
It is best to remove old paint or peeling varnish by brushing on a water-based paint remover.
Leave the product to react for a few minutes then use a scraper to remove all loose and peeling, bubbling paint. Be careful not to damage the wood and to work along the grain.
Use the right scraper for the surface at hand – always making sure to keep the straight sharp edge flat on the surface.
Steelwool is a great variant to prepare wood for varnishing or sealing.
With so many paint removal products on the market, heat is generally the last resort to removing a finish, as you could easily burn the wood. Heat can be applied to flat or slightly curved surfaces so that a scraper can be used to remove the softened finish.
2. Sand it down
You should sand surfaces by hand rather than with a sander so you can work with the grain. Machine sanders can create tiny swirls on the surface if left in one position too long and standing against the grain can also scratch the wood permanently. Use a sanding block when it goes about the flat surfaces) and a foam block when there are the curves. To produce really smooth surfaces the material should go through at least three ‘standings’ with successively finer grit sandpaper.
Pay attention that despite an exact grade you use, sandpaper operates by damaging the surface of the wood. And those final ones are very hard to see, you can’t notice them at the time the wood is varnished – but by keeping this ‘scratching’ idea in mind, it will stop from obsessive sanding. Depending on the hardness of the wood or the amount of material to be removed, start with 60 or 80 grit, then move to 120 or 160 grit and finish with 220 or 360 grit. The grade number appears on the back of the sandpaper sheet.
3. Power Sanding
There are different kinds of power sanders, but only one should be considered when doing fine finishing work: the orbital or random orbital sander. Correctly used, with a controlled pressure, it poses little danger of damaging the wood surface. In the hands of a novice, a sander can leave tiny swirls in the wood surface, regardless of the ‘fineness’ of the sandpaper – all it takes is clogged paper and a little too much pressure.
Pay attention that sanders will remove surface layers faster – which is often the ideal.
However, if you are new to refinishing (or the furniture piece is valuable) it is strongly recommended that you not use a power sander.
Use a cloth to remove dust between each sanding. Then use a cloth and turpentine to thoroughly clean the surface of the wood before staining, oiling, sealing or varnishing.
Seal it carefully
Make sure to gently stir varnish and never shake it or it will develop air bubbles that cannot be removed. Do not wipe your brush on the inside of the tin as this adds air bubbles and can spoil the finish. You will need to allow this first coat to dry overnight before you proceed on to the next step. Once the surface is completely dry, you will need to use fine sandpaper to lightly smooth the surface.
To test if the varnish is completely dry, and the surface lightly If sanding produces dust, then the varnish is ready to sand. If, however, rubbing the sandpaper across the surface produces tiny balls of varnish, then it is not dry yet. After sanding, wipe away any dust with a soft, clean cloth. Then, repeat the process with one or two more coats of varnish.
TIP:Don’t place the wood in direct sunlight to work on it. The heat will cause the varnish to dry too fast. Wood oil leaves a clear, satin finish that is extremely durable. Apply a liberal coat of oil over the wood surface with a brush or a cotton cloth and leave for a few minutes, apply a second coat of oil, working with the grain. Leave it to dry and apply a third coat if necessary. On new furniture, it is recommended that you apply oil once a week for the first month and thereafter once every six months. TIP When buying outdoor wooden furniture ask the manufacturer which oil to use and how often to apply it to achieve the tone you want.
Mixing and Thinning Varnishes
Varnish should never be thinned for second, third and fourth coats. However, for the first coat on hardwoods like oak, maple, and birch, a better result will be achieved by thinning the first coat by 25% with turpentine. This thin varnish sinks into and fills the wood cells or pores and attaches itself more firmly to the wood. Important It’s not wise to mix two or more kinds of varnish together, even if they are made by the same manufacturer.
Brush up your Skills
Use a good quality longhaired paintbrush when varnishing or sealing the wood. It’s important to use a new brush or one that is clean, dry and flexible. The better the brush – the better the finish. And make sure you use the right size for the job at hand:
25mm brush for window frames
50mm-75mm brush for doors, gates, etc
75mm or bigger for large surfaces like garage doors
Remember For brushing on varnish, you want a natural bristle brush as the bristles are absorbent and will help to minimize runs and lines in the finish.
How to apply a wood stain
New gel wood stains are easier to work with, give a more even spread and are less messy.
Wood stain will not take on previously painted or varnished surfaces, so sand any surface to be stained back to bare wood. Remove any traces of glue, which will act as a barrier and result in lighter patches. Fill all cracks and gaps with a wood filler which will absorb the stain. Note that some epoxy-based fillers are unsuitable for staining. If you’re using a water-based stain, first apply clean water to the wood to raise the grain. Then lightly sand the surface until it is smooth. If you’re using a solvent-based stain, simply sand the wood surface smooth. Apply the stain liberally, quickly and evenly over the surface. the area dry before applying a second coat. If the wood surface feels rough to the touch when the stain has dried, sand it lightly with fine sandpaper. Otherwise, wipe the surface with a clean cloth. Finish off with wax or varnish – bearing in mind that these will also darken the finish.