Under normal circumstances, soaking for 3-6 hours is enough.
The main thing is to wait until the water level reaches around 1.1-1.3. You can use a random inspection method and take 1. -5. Generally, 4 hours at normal temperature 25-30℃ is enough. Water bombs should be soaked in water at 30°C for 3 to 4 hours. But use boiling water to soak the water bomb directly. It can greatly reduce the water bomb casting time. The water bomb is actually a polymer material. It is made of water-absorbing resin. When placed in water, it will gradually absorb water and turn into water beads.