The powerfully alkaline solution, with a pH of about 14, is heated to 152C (306F), but because the digester is pressurised it does not boil.

In a cemetery this may take decades, depending on the conditions and the method of burial.

In the alkaline hydrolysis machine it takes 90 minutes, though the ensuing rinse cycle takes at least as long again.

After three to four hours, the door unlocks and the funeral director sees wet bones scattered across the metal tray, together with any medical implants the dead person had in their body.

Metal hip and knee joints come out in perfect condition.