CDC Kiln Technology & Firing Protocols Flashcards
6 cards from real CDC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CDC Kiln Technology & Firing Protocols flashcards as text
Which parameter most directly controls the surface gloss of a ceramic restoration during a glaze firing?
Answer: Peak temperature and hold time during the glaze cycle
Peak temperature and hold time determine how much the glass surface flows and self-glazes; too low a temperature produces a matte surface, while too high causes over-glazing and loss of anatomical detail.
What is the purpose of the isothermal hold or temperature plateau at peak firing temperature?
Answer: It allows full sintering and vitrification throughout the entire ceramic mass, ensuring uniformity
An isothermal hold at peak temperature gives the entire ceramic mass — core and surface — time to reach equilibrium, ensuring uniform density and optical properties.
A ceramist notices recurring blister-like surface defects on porcelain after firing. Which cause is most likely?
Answer: Moisture in the porcelain or contamination with organic material that vaporizes during firing
Blisters result from gas — steam, burned organics, or absorbed atmospheric gases — trapped below the surface that expands and erupts during firing.
Why is it important to follow the kiln manufacturer's recommended heating rate in degrees C per minute during porcelain firing?
Answer: Too fast a heating rate causes thermal gradients within the ceramic mass, leading to cracking, while too slow wastes time without benefit
Controlled heating rates ensure the entire restoration heats uniformly; rapid heating creates surface-to-core temperature differentials that generate tensile stresses exceeding the ceramic's strength.
What is firing shrinkage in dental porcelain, and how should a ceramist compensate for it?
Answer: The volumetric reduction of 15 to 25 percent as the green porcelain sinters; compensated by overbuilding to final dimensions before firing
Porcelain shrinks 15 to 25 percent by volume during sintering as particles fuse and voids close; ceramists must overbuild restorations before firing to achieve the desired final anatomy.
When using a programmed kiln cycle for zirconia sintering versus feldspathic porcelain, what is the primary difference?
Answer: Zirconia requires much higher peak temperatures of 1450 to 1600 degrees C and longer hold times than feldspathic porcelain at 900 to 980 degrees C
Zirconia sinters at 1450 to 1600 degrees C for 2 to 8 hours, while feldspathic porcelain fires at 900 to 980 degrees C in minutes — they require completely different kiln programs and often different kiln types.