This process uses building blocks to build a surrounding mold, and the bottom is sealed with sludge, or it can be sealed with building blocks. Silica gel chooses industrial grade or environmental protection grade according to its own requirements, and the hardness is recommended to be about 20 degrees, except for special requirements.
Industrial-grade mold silica gel uses a ratio of 100:2-5, and the viscosity is about 1.5w. If you think that the bubbles will not have much effect, you can not vacuum. The vacuum-less machine wants to have no air bubbles and reduce the proportion of curing agent added to extend the operating time.
The food grade uses a ratio of 1:1, the viscosity is about 3000, the viscosity is low, and there is no air bubbles, but do not heat and solidify if it is not vacuumed. Heating and curing will prevent the bubbles from being discharged quickly.