Lesson Notes By Weeks and Term v4 - SHS 2

Lesson Video

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Performance objectives

• Identify different types of wood finishes.
• Explain how to prepare a wood surface for finishing.
• Demonstrate applying finishes.
• Understand safety measures and work ethics.

Lesson summary

Welcome, future technicians and designers! Look around our classroom. See the desks, the chairs, the door, and the window frames. Now, imagine if they were all rough, splintery, and dull. Would they be pleasant to use? Would they last long, especially with our humid Ghanaian climate? Probably not. The final step in creating any wooden product, or 'artefact', is applying a finish. This is what transforms a simple piece of wood into a beautiful, durable, and valuable item. Whether it's the glossy shine on a chief's stool, the protective paint on a fishing canoe, or the smooth surface of a kitchen cabinet, finishing is a crucial skill.

Lesson notes

This lesson is divided into three main parts: preparing the surface, understanding the types of finishes, and applying the finish safely. Part 1: The Foundation - Surface Preparation

You cannot build a strong house on a weak foundation. Similarly, you cannot get a good finish on a poorly prepared surface. The goal of preparation is to make the wood surface perfectly smooth, clean, and ready to accept the finish.

Key Preparation Processes: Planing: This is the first step for rough-sawn timber. A hand plane or a machine planer is used to remove saw marks, make the surface flat, and reduce the wood to the required thickness. Think of it as peeling a yam to get to the smooth part. Scraping: After planing, a cabinet scraper (a flat piece of steel) is used to remove any fine marks left by the plane blade. It shaves off very thin layers of wood, leaving an incredibly smooth surface. Sanding (Glass-papering): This is the most common final preparation step. Sandpaper (or glass paper) comes in different "grits" (levels of roughness). You always start with a coarse grit (e.g., P80) to remove bigger scratches. Then you move to a medium grit (e.g., P120). You finish with a fine grit (e.g., P180 or P220) for a silky-smooth feel. Rule of Thumb: Always sand *with* the grain of the wood, not against it, to avoid creating new scratches. Filling: If the wood has any small cracks, nail holes, or knots, a wood filler or putty is used to fill them. The filler is chosen to match the colour of the wood. After it dries, it is sanded smooth with the rest of the surface. Cleaning (Dusting-off): After all sanding is complete, the surface must be completely cleaned of all dust. You can use a soft brush, a tack cloth (a slightly sticky cloth), or a cloth lightly dampened with methylated spirit to wipe the surface clean. Any dust left behind will get trapped in the finish and create a rough, ugly surface. Part 2: Understanding Wood Finishes

A finish is a liquid or solid material that is applied to the surface of the wood to protect it and enhance its appearance. Let's look at the five main types mentioned in our curriculum.

Evaluation guide

• Apply an appropriate finish to an artefact
• Critical Thinking and Talk for Learning Approaches: Learners think
• pair share to passionately identify and describe the tools and materials for
• preparation of surfaces of artefacts (cleaning -up).