Dry Pressing and Air Drying in Molded Pulp Production

Dry Pressing

Dry pressing refers to the process where molded pulp products, after being initially formed, are compressed under high pressure and temperature using heated molds. This method consolidates the fiber structure, resulting in:

Higher density and strength

Smoother surface finish

Lower final moisture content

Reduced post-drying requirements

Dry pressing is commonly used for high-quality, precision products such as electronic device trays, food containers, and premium packaging where appearance and dimensional accuracy are important.

Air Drying

Air drying is the traditional, simpler method of drying molded pulp products. After the wet fiber is formed into shape, the products are left in natural or ambient air conditions—often outdoors or in well-ventilated spaces—to allow moisture to evaporate slowly. Key characteristics include:

Low energy consumption (no artificial heat required)

Longer drying time (can take several hours to days depending on climate)

Softer texture and lower density compared to dry-pressed products

Often used for thicker, less-demanding items like egg cartons, industrial cushioning, and basic trays

Summary