CBJ Finishing and Polishing 2 — Questions and Answers
Question 1: What is the primary chemical composition of jeweler's rouge?
- Silicon dioxide (silica)
- Aluminum oxide (alumina)
- Ferric oxide (iron oxide) (Correct answer)
- Chromium oxide
Correct answer: Ferric oxide (iron oxide)
Jeweler's rouge is composed of ferric oxide (Fe₂O₃), a very fine iron compound that produces a high-gloss finish on precious metals.
Question 2: What does tumble polishing involve?
- Rolling a piece by hand across a flat abrasive surface
- Placing jewelry in a rotating barrel with abrasive media and burnishing shot (Correct answer)
- Applying heat while rotating the piece on a lathe
- Using ultrasonic vibration with chemical polishing solutions only
Correct answer: Placing jewelry in a rotating barrel with abrasive media and burnishing shot
Tumble polishing uses a rotating barrel filled with abrasive media or steel shot to uniformly polish and deburr multiple pieces simultaneously.
Question 3: Why should separate polishing wheels be used for different compounds?
- To prevent the wheel motor from overheating
- To avoid cross-contaminating compounds, which reduces polishing effectiveness (Correct answer)
- Because different compounds require different spindle speeds
- To comply with bench safety color-coding standards
Correct answer: To avoid cross-contaminating compounds, which reduces polishing effectiveness
Mixing a coarser compound like tripoli into a rouge wheel will introduce scratches during the final polish stage, defeating the purpose of the finer compound.
Question 4: What is 'bright cutting' in the context of jewelry finishing?
- Using a laser to engrave decorative designs into metal
- Cutting gemstones to maximize their light refraction
- Using a graver to cut sharp, polished facets directly into the metal surface (Correct answer)
- Applying a bright-dip acid solution to strip oxides from the metal
Correct answer: Using a graver to cut sharp, polished facets directly into the metal surface
Bright cutting is an engraving technique where a sharpened graver is pushed through metal to create highly polished, light-reflecting facets without additional polishing.
Question 5: What is the purpose of 'pickling' a jewelry piece after soldering and before polishing?
- To add a textured surface pattern to the metal
- To harden the metal before the polishing process begins
- To apply a protective anti-tarnish coating
- To remove oxides, firescale, and flux residue from the surface (Correct answer)
Correct answer: To remove oxides, firescale, and flux residue from the surface
Pickle solution (typically a mild acid) dissolves the oxides, firescale, and flux that form on metal during soldering, leaving a clean surface ready for finishing.
Question 6: What type of finish does a scratch brush used with soapy water produce on silver?
- A bright mirror finish
- A satin or matte finish (Correct answer)
- A hammered texture
- An oxidized antique finish
Correct answer: A satin or matte finish
A scratch brush (brass or steel wire brush) used with soapy water creates a uniform satin or matte finish by leaving fine, consistent scratches across the surface.
Question 7: What is the primary risk when polishing a jewelry piece near a prong-set gemstone?
- The polishing compound may permanently discolor the gemstone
- The metal will become too thin under the stone's girdle
- Friction and pressure from the polishing wheel may loosen or crack the stone (Correct answer)
- The stone's refractive index will be altered by heat
Correct answer: Friction and pressure from the polishing wheel may loosen or crack the stone
A spinning polishing wheel can catch on a prong, twist it, or apply enough lateral force to loosen a stone or fracture a brittle gem.
CBJ Finishing and Polishing 2
What is the primary chemical composition of jeweler's rouge?