温度・粘度
AFAP Cooling (As Fast As Possible)
Japanese: AFAP（自然冷却）
In the firing program, allow the kiln to cool naturally. Use this method within the strain range (below the strain point). This differs from “crash cooling,” in which the kiln is opened to cool the piece rapidly.
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AFAP (As Fast As Possible, natural cooling) is a method for specifying a section of a firing program in which the heating power to the kiln is completely shut off, allowing the kiln to cool at its natural rate (treatise §2.2). On a T-t plot, this appears as an exponential cooling curve determined by the furnace’s insulation performance. Since the cooling rate varies depending on the furnace type, size, and insulation performance, specifying “cooling is AFAP” rather than a program rate (ramp) such as “cool at X °C/h” achieves both cost savings on electricity and safety.
AFAP is primarily used in the “H” stage (the final stage of the 8-stage firing program), which involves cooling the glass to room temperature after it has dropped below the strain point. Below the strain point (approximately 442°C for the Bullseye system), the glass behaves as a rigid body and does not develop permanent residual stress; therefore, relatively rapid cooling is permissible (however, gradual cooling is sometimes chosen for thick pieces due to the risk of thermal shock). In addition, even during rapid cooling from the peak temperature (crash, Stage E), there is a variation that involves “opening the furnace lid slightly to cool faster than with AFAP.” It is essential to clearly distinguish between AFAP and “crash (forced rapid cooling).”
Related Concepts
ランプ（ramp）・ソーク（soak-hold）・軌跡言語（trajectory-language）・焼成プログラム8段階（firing-program-8-stages）・歪域（strain-zone）・Adams-Williamson則（adams-williamson-rule）
This entry is written in Japanese by Rei Chikaoka and translated for readers outside Japan. If something reads oddly, the original is the source of truth.