Indirect moxibustion places a material between the cone and the skin. Ginger warms the middle and is used for cold stomach pain and diarrhoea; garlic is acrid and dispersing and is used for nodules, tuberculosis and early abscess; salt is used almost exclusively at the umbilicus for collapse and cold; aconite cake warms the gate of life and is used for chronic cold deficiency of the kidney.
The material is not incidental. Each carries its own action, and the choice of interposed substance is as much part of the prescription as the point. Salt moxibustion at CV8 is the classic example, and it is still used for collapse in emergency settings.