CCE Selection & Application of Materials & Equipment for Ceramics 3 — Questions and Answers
Question 1: Which ceramic colorant produces a reliable blue color in both oxidation and reduction firing atmospheres?
- Copper oxide
- Iron oxide
- Cobalt oxide (Correct answer)
- Manganese dioxide
Correct answer: Cobalt oxide
Cobalt oxide consistently produces blue color across different kiln atmospheres, unlike iron and copper which are highly atmosphere-sensitive.
Question 2: What is the primary function of a pug mill in a ceramics studio?
- Bisque fire small pieces quickly
- Reclaim, deair, and homogenize clay (Correct answer)
- Screen raw glaze materials
- Test clay body shrinkage
Correct answer: Reclaim, deair, and homogenize clay
A pug mill reclaims scrap clay by compressing and de-airing it through an auger system, producing a homogeneous, air-free clay body.
Question 3: When applying glaze by spraying, which factor most directly controls the thickness of the glaze application?
- The firing temperature
- The specific gravity of the glaze and number of spray passes (Correct answer)
- The type of colorant in the glaze
- The bisque porosity alone
Correct answer: The specific gravity of the glaze and number of spray passes
Spray thickness depends on how much material is deposited per pass, which is governed by glaze specific gravity and the number of overlapping spray coats.
Question 4: Which material is commonly added to a clay body to open the texture and improve resistance to thermal shock in raku ware?
- Feldspar
- Grog (Correct answer)
- Whiting
- Zinc oxide
Correct answer: Grog
Grog (pre-fired, crushed clay) opens the clay body, reduces shrinkage, and improves thermal shock resistance critical for raku's rapid heating and cooling.
Question 5: A glaze recipe calls for a high amount of calcium carbonate (whiting). What role does calcium serve in the glaze melt?
- Primary glass former
- High-temperature flux and stabilizer (Correct answer)
- Opacifier
- Refractory filler
Correct answer: High-temperature flux and stabilizer
Calcium functions as a high-temperature flux that lowers melting point and also stabilizes the glaze melt, improving durability in the fired surface.
Question 6: Which type of pyrometer is best suited for continuous, real-time monitoring of kiln temperature throughout a firing?
- Optical pyrometer
- Thermocouple pyrometer (Correct answer)
- Radiation pyrometer
- Seger cone pyrometer
Correct answer: Thermocouple pyrometer
Thermocouple pyrometers generate an electrical signal proportional to temperature, allowing continuous digital readout and controller integration throughout the firing cycle.
Question 7: When wedging clay, what is the primary goal of the spiral (rams head) wedging technique?
- Increase moisture content evenly
- Align clay particles and remove air pockets without trapping air (Correct answer)
- Compress clay into a brick shape
- Mix two different clay bodies together quickly
Correct answer: Align clay particles and remove air pockets without trapping air
Spiral wedging uses a continuous rotational push that progressively expels air and aligns clay platelets without folding air back into the mass.
CCE Selection & Application of Materials & Equipment for Ceramics 3
Which ceramic colorant produces a reliable blue color in both oxidation and reduction firing atmospheres?