Finishing is the moment a project truly comes alive. It is the final layer of protection and the first thing a person sees and touches. I always say that a beautiful piece of craftsmanship deserves a professional finish. Finishing seals your work, guards it from wear, and deepens the beauty of the wood grain.
This guide provides a comprehensive roadmap for mastering wood finishing. I will show you how to prepare the wood, explain the different types of finishes, and walk you through the procedures for achieving a durable, beautiful result every time.
Preparing Wood for Finishing
The quality of your finish is directly related to the quality of your preparation. A perfect finish starts with a perfect surface.
Essential Surface Preparation Steps
You must clean the wood before applying any finish. Remove all glue squeeze-out, pencil marks, and any grease. I often use a clean cloth with mineral spirits to wipe down the wood. This also shows you how the grain will look once the finish is applied, revealing any spots you missed with the sander.
The Art of Sanding
Sanding is where you create the final canvas. You must never skip grits.
- Grit Progression: Start with a coarse grit (like 80 or 100) to flatten the surface. Then, move progressively through the grits (120, 150, 180, 220). Stopping at 220 grit is usually ideal for most furniture. Skipping a grit leaves deep scratches that the next grit cannot fully remove.
- Dust Removal: Remove all sanding dust before applying the finish. Use a vacuum, then a cloth dampened with mineral spirits, and finally, a tack cloth. Dust is the enemy of a smooth finish.
Sanding also plays a critical role earlier in woodworking, especially in shaping and smoothing. You can learn how these stages connect in my woodworking techniques guide.
Understanding Types of Wood Finishes
Finishes are categorized by how they protect the wood. You need to know the right type for the job.
Categorizing Finishes
| Category | Description | Examples | Primary Advantage |
| Penetrating Finishes | Soak into the wood fibers and harden within the wood. | Oils (Tung Oil, Danish Oil) | Enhances natural look, easy to repair. |
| Surface/Film-Building Finishes | Form a hard protective layer on top of the wood. | Polyurethane, Varnish, Lacquer | Maximum protection against water and wear. |
Key Characteristics of Different Finish Types
Your choice depends on your desired balance of durability and appearance.
- Penetrating Oils: These are easy to apply and repair. They offer low protection against scratches but enhance the wood’s feel and color. I love them for cutting boards and items that require a natural, food-safe look.
- Polyurethane: This is one of the most durable film-building finishes. It provides excellent resistance to water, heat, and scratching, making it perfect for tabletops and floors.
Detailed Guide to Specific Finishing Materials
You must know the application method for each finish to get professional results.
Wood Stains and Colouring
Stains are used to add color and highlight the wood grain.
- Types: Oil-based stains are common and allow a long working time. Gel stains are thick and do not penetrate deeply, making them great for woods like pine that tend to get blotchy.
- Application: Apply the stain generously, let it sit for the manufacturer’s recommended time, and then wipe off all excess completely.
Oil Finishes
These are my favorite for a deep, natural look.
- Tung Oil and Danish Oil: These are simple penetrating finishes. You simply wipe them on, let them soak in for 15 to 30 minutes, and then wipe off the excess. You must apply multiple coats for maximum protection. The finish is easy to maintain with a light reapplication every year or so.
Polyurethane
This finish offers the most protection for high-use items.
- Water-Based vs. Oil-Based: Oil-based polyurethane is more durable and gives wood an amber glow. Water-based polyurethane dries much faster, has a lower odor, and cures clear, making it popular for light-colored woods.
- Application: Apply thin coats and allow full drying time between applications. Lightly sand between coats with a very fine grit (like 320) to ensure good adhesion and a smooth final finish.
Shellac and Lacquer
These are evaporative finishes, meaning they dry quickly as the solvent evaporates.
- Shellac: A traditional finish often used as a sealant because it adheres to almost anything. A specialized application called the French Polish creates a deep, glossy shine.
- Lacquer: Lacquer is typically applied by spraying. It dries extremely fast, allowing you to build multiple coats in one day.
Step-by-Step Finishing Procedures
The process is always the same: prepare, apply the color, and apply the topcoat.
- Initial Preparation: Sand the wood up to 220 grit and remove all dust.
- Colouring (Optional): Apply your stain or dye and let it dry fully.
- Sealing: Apply a first thin coat of your topcoat, or a separate sanding sealer. This locks the color in and stiffens the wood fibers.
- Topcoat Application: Apply 2 to 4 thin coats of your chosen finish (oil, varnish, or polyurethane). Always sand lightly between coats with fine paper to knock down dust nibs.
Safety and Cleanup in Finishing
Finishes contain powerful chemicals. You must put safety first.
- Ventilation and Respirator Use: Work in a well-ventilated area. When using solvent-based polyurethanes, lacquers, or stains, you must wear a respirator rated for organic vapors.
- Fire Hazards: Rags soaked in oil-based finishes (especially Linseed Oil) can spontaneously combust. Always spread oil-soaked rags flat to dry completely outside, or store them submerged in a sealed container of water.
Conclusion
Finishing is the last step, but it is the one that lasts. It ties all your hard work together. I encourage you to practice and experiment with different types of finishes to find the one you love the most.
The reward is a strong, beautiful piece you will be proud to sign.
Wood Finishing Techniques FAQs
Q: What is the most important step in preparing wood for a finish?
A: The most important step is sanding up to 220 grit and removing all sanding dust. Any dust or small scratches you leave behind will be magnified dramatically once you apply the finish. Use a vacuum, then a cloth with mineral spirits, and finally, a tack cloth to ensure a completely clean surface.
Q: Is Tung Oil or Polyurethane more durable for a dining table?
A: Polyurethane is much more durable for a dining table. Polyurethane is a film-building finish that creates a hard, plastic-like layer of protection on the surface of the wood, making it highly resistant to scratches, heat, and water rings. Tung Oil is a penetrating finish that offers less surface protection.
Q: Why does my wood stain look blotchy on soft woods like pine?
A: Soft woods like pine have areas of varying density, causing them to absorb the stain unevenly, which creates a blotchy look. You must apply a pre-stain conditioner or a thin coat of shellac before staining. This seals the overly porous areas and allows the stain to penetrate more uniformly.
Q: What is the safest way to dispose of oil-soaked rags?
A: Rags soaked in oil-based finishes (like Linseed Oil or Tung Oil) can spontaneously combust. You must either spread the rags flat outdoors to dry completely or submerge them fully in a sealed metal container filled with water before disposing of them. This is a critical safety rule.
Q: Do I need to sand between every coat of finish?
A: Yes, you should lightly sand (scuff sand) between coats when using film-building finishes like polyurethane or lacquer. Use a very fine grit, like 320 or 400. This process knocks down any tiny dust nibs and roughs up the surface slightly, ensuring the next coat adheres perfectly for a smooth, professional result.