The custard can go from being like a solid ball...
What鈥檚 happening
This happens because of what custard is made of.
Custard powder is really just cornflour, colour
and flavouring (invented by Mr Bird after he found his wife was
allergic to eggs so she could not eat egg custard).
Cornflour is very finely ground flour. One of the
strange results of the fine grinding is that the particles made
will link together if you put a bit of pressure on them, but will
immediately separate when the pressure stops.
..to all stringy like this in seconds.
As long as you keep squeezing, those links join
together and the custard stays in a ball.
In the same way, the pressure of the spoon handle
causes a clean cut to form in the custard, but as soon as it passes,
the custard becomes liquid again.