ForMatter/Finishes/glaze/Crackle glaze (intentional crazing)
finish_glaze_crackle

Crackle glaze (intentional crazing)

glaze · translucent · crackleware, ge ware, intentional craze, crazed glaze

A clear or pale glaze tuned so the glaze contracts more than the body on cooling, breaking into a fine network of cracks that reads as veining. Often rubbed with ink or tea to highlight the lines. Song-dynasty Ge ware, Korean buncheong, Western art-pottery clear-crackle.

Glaze formulated with high alkali (Na₂O, K₂O) — fluxes that drop melting point but raise coefficient of thermal expansion. Body / glaze CTE mismatch: glaze ~7–10 × 10⁻⁶/°C vs. typical stoneware body ~5–6. On cool-down the glaze tries to contract more than the body holds it; the surface releases the strain by fracturing in a network. Crack pattern is a function of glaze thickness, cool rate, and CTE delta. Deliberate crackle: lower the body CTE or raise the glaze CTE. Accidental crackle is the same phenomenon called crazing — a defect when the body is meant to hold liquid through the cracks. Stained crackle: rub India ink, ferrous sulfate, or strong tea into the cracks while still warm.

character — fine spider-web crack pattern over a clear / pale glaze, ink-darkened lines, archaic register.

Finish properties

  • leveltranslucent
  • subcategorythermal-expansion mismatch glaze
  • applies toceramic
Pairs with materials

Second life

reversibilityzero — fired ceramic glaze cannot be unfired; the glassy layer is permanent. Damaged or chipped glaze can be re-glazed and re-fired with chemistry-compatibility planning.
blocks substrate recyclingno
renewabilitymoderate — re-glazing and re-firing is a studio-renewability path for damaged ceramic; the constraint is the original-firing temperature (the re-glaze must fire below the original).

Robin Hopper *The Ceramic Spectrum* (Krause, 2nd ed.); Daniel Rhodes *Clay and Glazes for the Potter*.

Citations