Woodworking Wood Finishing And Staining 1 — Questions and Answers
Question 1: What is the purpose of applying a wood conditioner before staining?
- To pre-raise and seal blotch-prone wood fibers so stain absorbs more evenly (Correct answer)
- To darken the wood before adding topcoat
- To clean dust and oil from the surface
- To raise the grain so it can be sanded smooth
Correct answer: To pre-raise and seal blotch-prone wood fibers so stain absorbs more evenly
Wood conditioner partially seals porous and blotch-prone woods like pine and birch, reducing uneven stain absorption and producing a more uniform color.
Question 2: What does 'raising the grain' mean in wood finishing?
- Dampening wood with water so fibers swell and can be sanded off for an ultra-smooth surface (Correct answer)
- Applying stain to make the grain pattern more visible
- Using a card scraper to lift torn wood fibers
- Heating the wood to open its pores before finishing
Correct answer: Dampening wood with water so fibers swell and can be sanded off for an ultra-smooth surface
Raising the grain involves wetting the wood surface so the fibers swell and stand up, then sanding them off when dry, resulting in a surface that remains smooth after waterborne finishes are applied.
Question 3: What is the difference between a film-forming finish and a penetrating finish?
- Film-forming finishes cure on top of the wood surface, while penetrating finishes soak into the wood fibers (Correct answer)
- Film-forming finishes are always water-based, while penetrating finishes are oil-based
- Penetrating finishes require more coats to achieve a protective layer
- Film-forming finishes can only be used on softwoods
Correct answer: Film-forming finishes cure on top of the wood surface, while penetrating finishes soak into the wood fibers
Film-forming finishes such as polyurethane and lacquer build a protective layer on top of the wood, while penetrating finishes like oil and wax soak into the fibers and harden within them.
Question 4: What grit sequence is typically used when sanding bare wood before finishing?
- Start with 80 or 100 grit and progress through 120, 150, and 180 or 220 grit (Correct answer)
- Start with 40 grit and jump directly to 220 grit
- Use only 150 grit for all sanding stages
- Start with 220 grit and work down to 80 grit
Correct answer: Start with 80 or 100 grit and progress through 120, 150, and 180 or 220 grit
Sanding through progressive grits removes the scratches left by the previous grit, and stopping around 180–220 grit leaves the wood smooth without over-polishing the pores.
Question 5: What is 'blush' in lacquer finishing?
- A milky, cloudy appearance in lacquer caused by moisture trapped during fast drying in humid conditions (Correct answer)
- The pink tint that appears in fresh shellac
- The glossy sheen achieved after buffing a cured finish
- Brush marks left in a brushed lacquer coat
Correct answer: A milky, cloudy appearance in lacquer caused by moisture trapped during fast drying in humid conditions
Blush is a milky haze in a lacquer film caused by moisture condensing into the fast-evaporating finish; it is corrected by adding retarder to slow evaporation or by applying a mist coat.
Question 6: What is the best method for applying an oil-based polyurethane finish to minimize brush marks?
- Apply thin coats with a high-quality natural-bristle brush, flowing the finish on and tipping off with the grain (Correct answer)
- Apply thick coats quickly with a foam roller for fast coverage
- Spray the finish and immediately wipe off the excess
- Apply with a cloth, rubbing in circular motions
Correct answer: Apply thin coats with a high-quality natural-bristle brush, flowing the finish on and tipping off with the grain
Flowing oil-based polyurethane on in thin coats with a quality brush and tipping off (lightly dragging the brush tip along the grain) minimizes brush marks and trapped bubbles.
Woodworking Wood Finishing And Staining 1
What is the purpose of applying a wood conditioner before staining?