All About Wood Finishing - From Raw to Refined
Wood has been a cherished material for crafting furniture, cabinets, and decorative items for centuries, thanks to its timeless appeal and inherent warmth. However, its true potential shines through when complemented with impeccable wood finishing techniques. More than just a concluding touch in woodcraft, the right finish accentuates the wood's grain, imparts depth and richness, and ensures the crafted piece stands the test of time. Mastering this finishing touch can transform an ordinary creation into a true masterpiece.
The Reason for Wood Finish
Wood, inherently permeable, readily absorbs moisture, dirt, and oils. This vulnerability emphasises the primary reason for applying a finish: protection. Beyond merely enhancing aesthetics with stains that highlight and add colour to its grain, wood finishing shields wood from external elements like moisture, UV rays, and everyday wear and tear. A topcoat seals in colour and increases its lifespan. If the wood was left unfinished, it is prone to swelling, cracking, or rotting. However, with the right finish, not only is the wood's longevity ensured, but its natural beauty and warmth are also magnified.
Types of Wood Finishes
There are 2 categories of wood finishes: Penetrating Wood Finishes and Surface Wood Finishes. The choice of the right wood finishes based on the desired appearance of the wood, the wood type, its intended use, and the level of protection.
1. Penetrating Wood Finishes
Penetrating wood finishes are favoured for revealing a natural appearance to wood pieces. As the name suggests, this wood finishes penetrate deep into the wood, offering protection against drying, cracking, swelling, and rotting. All the wood finishes below can be applied either by brush or cloth.
i) Tung Oil
Tung oil, which is obtained from the nut or seed of tung tree, is one of the most popular penetrating wood finishes that is environmentally friendly. Tung oil wood finish is highly resistant to water, protecting wood pieces from moisture damage, insect attacks, cracks and dents to enhance durability and natural appearance of the wood.
ii) Linseed Oil
Linseed oil, which is made from flax seeds, is easy applicable by using a brush or cloth, this wood finishes aim to have a natural look with a warm, yellow matte tone that darkens with age. It is water resistance however has a slow-drying disadvantage.
iii) Danish Oil
Danish oil is a wood finish that is made from polymerized linseed or tung oil, it is a highly durable wood finish that offers air-hardened protection, improves wood colour and water resistance, and it is easy to apply.
iv) Cedar Oil
Cedar oil, which is derived from aromatic red cedar, is a favoured choice for wood finishing due to its distinctive woody odour and multifaceted benefits. Not only does it offer a warm, silvery-grey appearance ideal for floors and furniture, but it also rejuvenates the wood and infuses it with natural insect-repellent properties, protecting against insects, swelling, and rot. It's versatile and can be applied to any wood type.
2. Surface Wood Finishes
Surface wood finishes are applied to the surface of the wood to create a durable and protective layer. This type of wood finishes are considered to be an excellent option for furniture and materials that are exposed to a high level of wear and tear that endure frequent use.
Shellac finishes brings out the rich grain in wood after the alcohol evaporates, this wood finish adds a protective coat and smoothness to the wood surface while giving the wood a warm glow, however Shellac is reasonably durable as it is sensitive to heat that is not recommended to be used for tabletops. Shellac wood finishes can be applied by sprayers or badger hairbrushes.
Lacquer can be applied with a sprayer or natural bristle brush. This wood finish usually results in a hard and durable finishes which is resistant to damage and is ideal for protecting wooden furniture, cabinets, doors or shelves. However, as time passes, lacquer may experience a change in colour and develop scratches.
Varnish is a type of clear wood finish that highlights the natural characteristic of a piece of wood. This wood finish is water resistant and less susceptible to UV lights making it perfect for outdoor wooden furniture. Varnish can be applied with a sprayer or paint roller for the best result.
Wax, which is usually made by carnauba wax, is a type of wood finish that is easy to apply and protects the wood from moisture. However, it is not durable and does not offer protection from heat and requires frequent reapplication. Wax can be applied with a cloth, brush or sprayer.
Polyurethane wood finish is the most durable and water-resistant wood finish for indoor woodworking projects that offers excellent protection. It can be applied by natural bristle brush. There are 2 forms of polyurethane: oil based, and water based. Water-based polyurethane dries rapidly and has minimal toxicity and odour, though it might not effectively withstand high temperatures or strong chemicals. On the other hand, oil-based polyurethane offers greater durability but comes with increased toxicity and a stronger smell.
Stain is a type of wood finish that can enhance the grain pattern of wood, commonly used to protect woods from water and UV radiation, preventing them from cracking, drying or rotting. It is recommended to use stain with a surface wood finish.
Paint is a basic wood finish that fully covers and protects the surface. Paint is commonly used for both indoor and outdoor projects that gives a plain appearance on wood pieces.
Key Considerations When Choosing the Right Wood Finish
When selecting a wood finish, several factors come into play, the desired appearance, wood type, drying time of wood finishes, durability, its exposure to sunlight and humidity, safety, ease of application and environmental impact. The finish's impact on the wood's appearance, drying time should be taken into account.
1. Desired Appearance
The type of wood finish you select can drastically affect the appearance of the wood. Do you prefer a glossy or matte appearance? Some wood finishes like varnish tends to be glossier while oils often result in a more natural, matte look.
2. Wood Type
As different types of wood varieties react distinctively with different wood finishes, it is important to choose a wood finish that is suitable match. Some woods have greater porosity that will influence the wood finishes adherence.
3. Drying Time of Wood Finishes
This is crucial if you are working on a time sensitive project as drying time of different wood finishes are different. Oil-based wood finishes generally take longer to dry than water-based ones. When time is limited for a wood project, opt for wood finishes that dry quickly to ensure efficiency.
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An enduring wood finish must shield against sunlight, heat, and physical harm such as scratches, chemical abrasions, and solvent impacts. Durability levels vary among wood finishes. Floors and countertops, for instance, would require a more durable wood finish than a decorative piece.
5. Exposure to Sunlight and Humidity
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Some of the wood finishes are vulnerable while others offer better resilience. Wood finishes are susceptible to damage from humidity and sunlight, leading to warping, cracking, and discoloration. Certain wood finishes, offer exceptional UV protection and moisture repellence to preserve wood aesthetics over time.
Some wood finishes, particularly oils, can be flammable in their wet form, as a result, always be aware of the wood finishes’ safety guideline.
7. Ease of Application
Certain wood finishes are easier to apply than others, whereas some wood finishes can be applied with a brush or roller, others need to be sprayed on. If you are a beginner of wood finishes, you might want to steer clear of wood finishes that require precise application methods.
8. Environmental Impact
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Choose eco-friendly wood finishes, like certain water-based polyurethanes and natural ingredient, instead of traditional wood finishes that are made from petroleum-based ingredient to minimise the impact on environment and suitable for use in the presence of children and pets.
Wood Finishes Application Process
1. Surface Preparation
Start by sanding the wood to create an even surface. Begin with a coarse grit sandpaper and progressively move to finer grits for a smooth finish. Sanding removes surface imperfections and opens up the wood's pores to accept the wood finish better. After sanding, remove all dust and debris from the wood to ensures that dust particles don't mix with the finish to cause an uneven application.
2. Application of Stain
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When staining wood, first test the colour on a scrap piece to ensure the desired result. Apply the stain evenly, going with the grain by using a brush or cloth in a ventilated space, wearing gloves. Wipe off excess with a clean cloth for evenness. Allow it to dry thoroughly before applying wood finishes, which might take hours or overnight, based on the stain type and environmental conditions.
3. Choose the Right Wood Finish
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Different projects may require different wood finishes. For example, a dining table may benefit from a protective polyurethane coat, while a decorative sculpture might be best suited to an oil finish for a more natural look. Research or consult with a professional to determine the best wood finish for your specific project.
4. Select the Applicator
Different wood finishes require different applicators. Brushes, rags, foam brushes, and spray guns are some options available.
5. Application Technique
Before using a finish, gently stir it to mix settled components, avoiding shaking which can cause bubbles on the wood. It's recommended to apply several thin coats instead of one thick layer for evenness, faster drying, and a sleek finish. Always work in the direction of the wood grain to minimize brush marks and maintain uniformity. Let each coat dry completely, and consider lightly sanding between coats using fine-grit sandpaper to enhances adhesion and corrects any imperfections for the next coat.
After the final coat, let the wood finish dry thoroughly. While the surface might feel dry to touch within hours, it can take days or even weeks for some wood finishes to dry completely. During this period, avoid placing heavy objects on the surface or exposing the wood to extreme conditions.
How to Maintain Wood Finishes
1. Clean Regularly
Regularly dust the finished wood with a soft, lint-free cloth or a microfiber duster to prevent dirt accumulation which can lead to scratches. When cleaning, use mild soapy water or wood cleaners. It's crucial to avoid abrasive or ammonia-based solutions, as these can damage the wood finishes.
2. Protect from Environmental Factors
Prolonged exposure to direct sunlight can cause the wood finish to fade or become discoloured. Use blinds, curtains, or UV-protective films on windows to minimize sun damage. Also ensure the wood is not exposed to prolonged moisture or high humidity. Use coasters to prevent moisture rings from hot/ cold beverages, and wipe spills immediately.
3. Repair Minor Issues
To maintain finished wood, address minor scratches with touch-up pens or soft wax repair sticks that match the wood’s colour; lightly sand the affected area with deeper damages and reapply the wood finishes; with white rings from hot dishes or cups, they can often be removed using with baking soda and water or specialised products designed for this purpose.
4. Avoid Chemical Exposure
Avoid exposing the wood finish to harsh chemicals, such as nail polish remover, household cleaners, or paint removers. If exposure occurs, clean immediately and assess if the wood finish needs to be repaired.
5. Refresh and refinish
Periodically, wood finishes benefit from waxing to restore shine and offer extra protection; buff the wax with a soft cloth. Oil-finished surfaces occasionally need re-oiling post thorough cleaning. Over time, with significant wear, the wood piece might require professional refinishing. If in doubt about the best approach to extensive damage, seek expert advice.
Wood, with its enduring allure, serves as the canvas for many masterpieces, but it's the wood finish that elevates its beauty and ensures longevity. The wood finish you select should be in harmony with the wood's purpose, its exposure to elements, and the desired visual outcome. Also, proper application and maintenance will ensure that your wood pieces remain beautiful and durable for years to come.
Remember, while wood tells a story, the finish amplifies it, preserving its tale for generations to come.
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