Simply put, flour contains gluten, that is, plant protein. Even low-gluten flour will form dough when stirred with cold water. However, cooked flour is treated wheat flour without gluten, which is equivalent to "raw flour" used in daily life. It is not easy to form dough with cold water, so it is often easy to form dough by boiling water. The cooked flour feels smooth and tender, and it is translucent after being cooked with boiling water. The skin of Cantonese dim sum is usually made of cooked flour.

It is said that flour is kneaded into dough, rubbed and washed in water, and finally gluten is left. The wheat flour obtained after precipitation, dehydration and drying in gluten washing water is clear flour, which is also the origin of "clearness".