Hermetic Storage Bags & Chemical-Free Grain Storage

A hermetic (airtight) bag is a sealed liner — often a triple-layer PICS bag, GrainPro cocoon or similar — that traps grain in an airtight space. Once sealed, the grain and any resident insects keep breathing, using up the oxygen and building up carbon dioxide until the pests suffocate. No fumigant or chemical is needed; the seal alone protects the grain.

Bags = grain quantity ÷ bag capacity, rounded up. The last bag is usually only part-full, so the tool shows both the total number of bags and how much grain goes in that final part-bag. For example 850 kg of grain in 50 kg bags needs 17 bags, with the 17th holding 50 kg and the rest full — or 880 kg needs 18 bags with the last holding 30 kg.

Insects, mould and the grain itself respire inside the sealed bag, consuming oxygen and releasing carbon dioxide. Within days to a couple of weeks the oxygen drops low enough and CO₂ rises high enough that insects die and mould growth stalls. It's a purely physical, residue-free method — ideal for seed, food grain and organic produce.

Hermetic bags suit cereals (wheat, paddy, maize, sorghum), pulses (chickpea, pigeon pea, beans), and oilseeds, as well as seed grain. The key is that the grain is dry and clean before sealing — hermetic storage stops pest damage but cannot dry wet grain or fix mould that has already started.

Grain must be at or below its safe storage moisture before going into a hermetic bag — roughly 13–14% for cereals and lower for oilseeds. Sealing damp grain traps moisture and can cause caking or mould. Dry the grain first, then fill and seal; check our Safe Storage Moisture calculator for the limit for your crop.

Common PICS-style liners come in 25, 50 and 100 kg sizes; cocoons and bunkers run far larger. Enter the rated capacity of the bags you'll use. If you fill to the brim it's harder to seal cleanly, so many farmers leave a little headroom — use the practical fill weight you actually achieve as the capacity.

Properly dried, clean grain in an intact, well-sealed hermetic bag can keep safely for many months — often a full season or more — with negligible insect damage and no weight loss. Keep bags off the floor, away from rodents and sharp edges, and reseal immediately after each opening to restore the airtight environment.

Often yes — quality inner liners can be reused for several seasons if they stay free of punctures. Inspect each liner for holes before refilling, since a single pinhole lets air in and defeats the seal. Store empty liners clean and dry, and keep the outer woven sack to protect the liner from abrasion and rodents.

The bag count is exact arithmetic for the capacity you enter; the part-bag tells you the leftover. Real-world needs vary with how full you pack each bag and how much headroom you leave for sealing. Treat the result as your purchase and packing plan, and buy a spare bag or two for the part-fill and for replacements.