Rendering fat: and cooking in what runs out

How to tell it is going right

• It started cold or low and came up slowly: fat that met a hot pan seizes and scorches before the inside can melt, and there is no recovering it.
• The fat in the pan is clear and clean-smelling, pale to golden, with no dark sediment on the floor and nothing acrid in the steam.
• What is left behind is crisp and deep gold with no soft pale fat still clinging to it and no black burnt edges.
• There is a real volume of it: enough to film the pan floor and be poured off and kept, not a dry smear that never ran.
• Whatever cooks in it browns in it and takes its flavour, rather than sitting in a greasy pool that never gets hot enough to colour anything.

Where it goes wrong The heat was raised to hurry it along, so the outside seized and browned before the interior fat could melt; very little runs out, and the solids come out burnt on the outside and rubbery within.