This substance is often added to the dough of Cantonese moon cakes.

According to the national standard of moon cakes, water is necessary to make Cantonese-style moon cakes, which is the characteristic method of making Cantonese-style moon cakes.

When making Cantonese-style moon cake crust dough, a substance called "scooping water" is often added. Guishui is a common traditional auxiliary material of Cantonese pastry. It is an alkaline solution with a PH of 12.6, which was obtained by boiling plant ash with water for one day and taking the supernatant. The main components of plant ash are potassium carbonate and sodium carbonate. In the absence of modern chemical alkali in history, the plant alkali prepared by this indigenous method has to be used.

The water scooping used now is not plant ash, but an alkaline mixture made of potassium carbonate and sodium carbonate as the main components, supplemented by carbonate or polyphosphate according to the composition and principle of plant ash, which is the same as plant ash's water scooping in function, so it is still called water scooping. If only potassium carbonate and sodium carbonate are used to make water, its properties are very unstable and it is easy to fail and deteriorate after long storage time. Generally, 10% phosphate or polyphosphate is added to improve water retention, viscoelasticity, acid-base buffer and metal barrier.