Shelf · Sauces & emulsions · Low heat
Nappe
The doneness checkpoint for a custard or a sauce: it clings to the back of a spoon thickly enough that a finger drawn through leaves a clean lane.
- The temperature band
- The liquid · 75 to 85 °C
Why it works
It is a thickness you can see rather than a temperature you have to measure, and for egg custards it lands right in the narrow window where the proteins have set but have not yet curdled. Roughly 80 °C — a few degrees past it and you have scrambled eggs.
The tell
Lift the spoon: the sauce coats it evenly instead of running straight off, and a finger stripe across the back holds its edges without flowing back together.
- Runs off
- Holds a lane
- Curdled
How it fails
Once it goes past this point it curdles and no whisking undoes it — pull it off the heat while it still looks slightly thin, because it thickens further as it cools. If fine grains have just appeared, blitzing or straining immediately can still save it.
In the app, the card opens on the recipe step that names it, with the tell drawn.
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