Cold zones found at screening

01Symptom

Undigested material with original colour and structure appears at screening, usually from one side of the pile.

2 published logs ran into this — linked in section 04.

02Why it happens

03What to do

1. 01 At every turn, put the outer 20 cm of the old pile into the middle of the new one.
2. 02 Add 1 L of water per 10 kg of material in dry weather, straight onto the new core.
3. 03 Turn into a second bay rather than in place.
4. 04 Screen and return cold material to the next batch rather than spreading it.

04Where this has come up in the logs

• batch logOffice shred and delivery cardboard, 300 L insulated bin20 Sep 2026 · insulated bin · 30:1 · 64 °C
• batch logA 6 m windrow of municipal green waste, turned four times05 Oct 2026 · windrow · 30:1 · 78 °C

05Related logs

• methodCold composting: the pile that takes a year and needs almost nothing08 Oct 2026 · wire bay · 35:1 · 29 °C