The drying process is a critical step in molded pulp production as it helps to remove moisture from the wet pulp and solidify the shape of the product. There are two main drying methods used in the production of molded pulp: dry press and wet press.
Dry Press Drying
In the dry press method, the molded pulp is dried in the open air, typically on a flat surface or in a drying rack. The molded pulp is left to dry until it reaches a sufficient level of dryness, which is typically around 50-70% moisture content. During this time, the surface of the molded pulp is very rough and is out of the shape. Then the dried molded pulp is removed from the drying surface and transferred to a mold for further pressing to get a smoother and shaped appearance.
Wet Press Drying
In the wet press method, the molded pulp is dried while it is still in the mold, typically using hot air or steam. The molded pulp is pressed while it is still wet, pressure is applied to remove excess water. And at the same time, heat and hot air is used to evaporate the water. The wet press method typically requires specialized equipment and can be more complex and time-consuming than the dry press method, but it results in a smoother and more complex molded pulp product.
The two main drying methods used in the production of molded pulp are the dry press and wet press methods. The choice of drying method will depend on the desired properties of the final product, as well as factors such as production volume, equipment availability, and cost.