Carbonisation

In detail

Heat a sugar, a protein or a fat far enough in air and it does not merely dry — it decomposes, losing hydrogen and oxygen and leaving behind a carbon-rich solid bonded to whatever it was sitting on. That is carbonisation, and it is why a burnt pan, an oven wall, a grill pan and the base of a hob resist everything that works on ordinary kitchen soil. The deposit is no longer emulsifiable, because emulsification requires an oil and there is no longer an oil. Three routes address it and each has a cost. Mechanical removal works and abrades whatever is under it, which is why the cooker manufacturer permits an abrasive cleanser and steel wool on its oven shelves and forbids both everywhere else in the appliance. Strong alkali converts the remaining fatty fraction to soap and undercuts the carbon, which is what oven cleaner does and why it attacks aluminium in the process. And pyrolysis — a self-cleaning cycle — takes the deposit past decomposition to ash, which is why the manufacturer says white ash simply wipes off afterwards. Prevention is disproportionately effective here because the transition is one-way: a spill removed before the next heating cycle never becomes this problem.

Why

• Burnt-on food and carbon deposits is explained by Carbonisation
• Ceramic hob cleaner is explained by Carbonisation