Wood coating provides durable protection for the beauty of wood
Wood is a wonderful, versatile building material that has been used for thousands of years to construct everything from walls and floors of the family home to the furniture and cabinetry that fill it. In order to keep wood functioning at its best and most beautiful, it needs to be protected from abrasion, chemicals, moisture, UV radiation, weathering, and attack from microbes such as fungi and mould. This is the job of wood coatings. With such a wide range of substrates (hardwood, softwood, MDF, aged wood, or green wood) and applications (exterior, interior, furniture, building, residential, industrial, deck coating to french polishing) it is no surprise that wood coatings is a billion dollar industry with a glut of players and products.
In this article we provide an overview of wood coatings technologies and products, and the big brands and companies that make up the industry. As well as traditional coatings such as stains and varnishes we look at newer technologies such as powder coating, polyurethanes, and specialised wood coatings.
The 6 main types of wood finishes
Varnishes, shellacs, stains, lacquers, polyurethanes, epoxies, and other wood finishes all have properties which work best when paired with the right application. Which wood coating you need depends on the type of wood and the end use of the substrate. A lot of these terms are used to refer generally to a finish, even though they denote specific finishes. Below is a brief description of different wood coating types and their properties.
- Lacquer is a form of finish in which the resin is dissolved in a solvent (unlike shellac which uses alcohol). It is harder than shellac, and is used to give a clear or coloured shiny, glossy finish for furniture. The high VOC content in lacquer makes it a less popular option than water-based varnishes.
- Shellac is a softer form of finish which uses naturally-occurring resin (the shellac) dissolved in ethanol to provide a colour and high-gloss finish for wood products. Shellac is now mostly used for furniture and instruments as it is not as durable as varnish, and alcohol spills will cause the shellac to dissolve.
- Varnish is a transparent protective finish that dries hard and usually glossy (though they can be matte or semi-gloss). The basic components of varnish are a drying oil, resins, and a solvent, and the resin can be acrylic, oil, polyurethane, epoxy, and others. A varnish is a hard-wearing finish which is suitable for both indoor and outdoor use as it is waterproof, durable, tough, and versatile. This property makes it particularly popular for deck coating.
- Wood stain is a coating which consists of dyes or pigments dissolved in a vehicle with a small amount of binder. When applied it soaks into the wood substrate and, depending on whether it is transparent or opaque, accentuates the wood grain or flatten out the wood with a colour. Stains are used to give wood a particular colour, and not for protective properties. If protection is needed a clear varnish is often applied over the top.
- Wood oils offer protection while letting the surface retain its natural beauty. The oils are additionally easy to apply and maintain. The oils exist as Danish, teak, linseed, mineral and tung oil
- Wood paint does not penetrate the wooden surface but forms a transparent or opaque film on top of it. The paints also form a uniform surface hiding the texture of the surface. Before applying wood paint, applying a primer is recommended. Chalk paint and milk paint are both examples of a wood paint.
The protective wood coating system
Whether using paint, varnish, or stain it is important to use the correct application methods and processes for wood finishes. A primer cannot be used as a final topcoat, and though some topcoats can be applied as all-in-one systems, not all can.
Industrial wood coating – wood preservative
Impregnation is a wood preservation method where protective chemicals are ‘impregnated’ into timber through the application of pressure. It makes the timber more durable and protects it from pests such as mould, fungi and insects. The preservatives are copper-based (a natural biocide), sodium silicate, thinned epoxy resins (preservative and sealer in one), or oil-based (coal-tar creosote).
Impregnation is an industrial wood coating treatment used to protect telegraph poles, railway sleepers, outdoor structures such as decks and playground equipment, as a building material in domestic, commercial, and public buildings, and more.
From primer to topcoat
When it comes to wood coatings, the intended end use of the wood is vital for choosing the coating system. Exterior wood needs all the protection it can get, and a primer not only protects the wood from the environment, but also prevents cedar bleed and tannin stain – where the tannins from the wood are drawn to the surface and stain the paintwork. Acrylic sealing primers are one such coating, that both seals and protects. A primer also works to connect the wood substrate with the coating, ensuring adequate adhesion.
Surface finishes are those that do not penetrate the wood. Decorative paints, varnishes, lacquers, and shellacs are surface finishes, and so they dry to form a protective film on top of the wood. A clear topcoat protects the layers beneath while enhancing the final finish and providing abrasion and stress resistance. When working with a stain (which is a penetrative coating), a varnish or other surface coating will enhance and protect the colour.
The proper protection for hard & softwood with wood finishes
Any type of wood is suitable for a protective coat. However, the best wood coating product may differ for different kinds of wood.
SOFTWOOD: Spruce, Larch, Pine, Douglas, Cedar and most types of regular timber
Soft wood types can have trouble absorbing wood coating evenly, which can create a splotchy look. A pre-stain conditioner or primer applied to the wood prior to coating can smooth out the finish on these softwoods. After applying the stain of your choice to your project, you need a durable top coat that will keep your wood finishes looking great for years to come.
Recommended products: Primer + Stain + Polyurethane Wood coating or oil or wax based products
HARDWOOD: Maple, Bamboo, walnut, red birch, cherry, teak, pine
Most unfinished hardwood floors require one coat of sealer and at least two coats of protective finishing. Staining is not a good idea for most exotics, because of their cell structures and hardness. Furthermore we recommend a water based coating for most types of hard wood, unless you have chosen a dark coloured wood. Then an oil based wood coating will enhance the beautiful dark colour.
Recommended products: Sealer + Water or Oil based Polyurethane Wood coating + top coating
Specialty wood coating developments
Wood coatings are not just about protecting the substrate while letting the beauty of the wood shine through. With technologies improving all the time, it is possible to powder coat wood substrates now, as well as protecting them from fire or making a deck anti slip. Below is more information on these specialty wood coatings.
- Fireproof systems for wood – Fire is one of the greatest dangers for wood. There are two coating formulations that act as passive fire protection measures for wooden substrates: intumescent and fire retardant coatings. Intumescent coatings swell up in the presence of extreme heat, forming a protective layer of char between the wood and the fire. Fire retardant paints work by releasing flame-damping gases to prevent ignition.
- Wood powder coating – Powder coating is the process of using electrostatic charge to cause a dry powder to adhere to a substrate and then baking and curing the powder in an oven. The resulting coating is immensely durable and attractive, as well as being environmentally friendly due to the lack of solvent. Powder coating wood is now gaining widespread popularity, particularly for coating furniture.
- Making wood slip resistant – Wooden surfaces can be very slippery when wet, whether decking, stairs, ramps, or walkways. A slip resistant paint system works through the inclusion of a non-slip aggregate or by creating a rough surface that provides more grip in wet or dry conditions.
Wood coating Canada – The local specialists and products
The wood finishes market is filled with recognisable and trusted brands and products. Globally, the big players are Sherwin-Williams, Axalta, Rust-Oleum, AkzoNobel, and PPG through brands such as Flood, Sikkens, and Sher-Wood. If you want more information about the various uses and advantages of wood, head to the Canadian Wood Council page. Below you can find a selection of wood coatings available in Canada.
If you would like more information about the best wood coatings for your project, let us know! Our experts are here to help. In collaboration with our coating partners, we will find the coating solution for your needs and help you to get the best results possible for your project’s finish. Simply click the button below and tell us a little about your project to get started. The quote service is completely free, get in touch today!
|Wood Coating Company/Brand||Wood Coating Product||Description|
|PPG Proluxe||Transparent Matte – Cetol SRD Wood Finish||A one-coat, transparent exterior wood finish for siding, railings and decks. Solvent-based penetrative coating in a range of colours.|
|Sherwin-Williams||Wood Classics Polyurethane Varnish||A solvent-based polyurethane finish with a satin or high gloss finish. For interior floor use.|
|Axalta||Zenith Waterborne Basecoat||A single component, high performance waterborne lacquer designed for finishing fine woodwork and cabinetry|
Tips for the DIYer – 5 wood coating problems and solutions
Wood is not always the easiest substrate to coat. Though you might think deck painting is simple, there are several phenomena which may negatively affect the coating process if the surface is not appropriately prepared. The following tips may save your coating job!
1. Knots & resins
Knots and resins may cause trouble when coating softwood such as pine, spruce or latch. To minimise the risk of these ruining the finish, remove the dead knots and apply wood filler to fill the holes. You can try removing live knots by using a heat gun. The resins can best be removed with methylated spirits, however, be sure not to use white spirit.
2. Rotting & decaying
Some wood sorts are more prone to rotting and decaying than others. Most softwoods my suffer from early rotting if not treated appropriately. Therefore, you should always pre-treat softwood with preservatives to make the surface last longer.
3. Tannin bleeding
Many coloured timber types such as oak and (western red) cedar are prone to tannin bleeding. To prevent damage caused by tannin bleed, degrease the surface with methylated spirits and be sure to thoroughly coat the surface. Pay especially attention to the end grains.
4. Acidic tannins & discolouring with metal fixings
Some hardwoods such as oak, and high density softwoods like cedar contain acidic tannin which leads to discolouring. To reduce the risk for discolouring, degrease the surface with methylated spirits and avoid using fixings of ferrous metals such as steel.
5. Oil, gums or extractives content
Some hardwood types such as teak contain oils, gums or extractives which lead to slow drying and poor adhesion. To solve the problem, use methylated spirits to degrease the surface and allow the wood coating (s) additional time to dry.