Alternative Firing Methods · Raku Firing

Hard

Control crackle pattern in Raku

Raku crackle glazes crack when the hot glaze hits cooler air. The cracks fill with carbon from the reduction chamber, creating dark lines on a light glaze. But how much crackle and how dark: that you can influence.

The experiment

Fire three pieces with the same crackle glaze but different post-firing treatments:

  1. Heavy reduction: packed tight with newspaper, sealed well, 15 minutes
  2. Light reduction: few wood shavings, loosely covered, 5 minutes
  3. Open air cooling: no reduction chamber at all

Compare

  • Heavy reduction: dramatic dark crackle lines, carbon-blackened bare clay
  • Light reduction: lighter crackle, less carbon in the lines
  • Open air: minimal or no crackle pattern, lighter overall color

What you're controlling

  • Amount of combustible material = intensity of carbon penetration
  • Duration in the chamber = how deep the carbon goes
  • Seal tightness = how much oxygen is available (less O₂ = more smoke = more carbon)

This is where Raku stops being luck and starts being intention.