By Biolastic Team · 8/11/2026
Specify 5kg, 10kg and 25kg compostable flour liners with practical sizing, moisture, seal and food-contact checks. A B2B wholesale buyer guide.
A flour mill can buy a liner that fits neatly inside a sack and still discover problems after filling: powder trapped in the seal, a torn corner during handling, or caking after storage. Those failures affect more than the packaging bill. They create repacking, customer complaints and uncertainty about shelf life. For mills, bakery-premix manufacturers, ingredient distributors and private-label packers, the better starting point is to define the product, the outer sack, the filling method and the journey before asking for a bag rate.
This guide focuses on 5 kg, 10 kg and 25 kg compostable flour and dry-food ingredient liners. It is intended for procurement teams worldwide and for buyers around Siliguri, North Bengal and India. It explains what to measure, which tests to request and how to compare quotations without assuming that every compostable film behaves alike.
Biolastic lists a Compostable Flour & Dry Food Ingredient Liner Bags – 5 KG, 10 KG & 25 KG product for flour mills, food ingredient manufacturers, bakery premix suppliers and related businesses. These are nominal application capacities, not proof that any flour at a given bulk density will fit every liner or outer sack. The product is a specification-led enquiry item. Confirm actual layflat dimensions, gusset, film construction, thickness, closures, test documents, MOQ unit, lead time and pricing with the supplier.
The listing's product category does not, by itself, establish a particular oxygen or water-vapour barrier, food-contact compliance for every destination, third-party certificate for every supplied batch, or overseas delivery. None of those claims should be inferred from the word compostable. A buyer should ask for documentation corresponding to the actual material and finished liner.
Flour, atta, grain-based mixes and powdered bakery ingredients vary in bulk density and flow. The same nominal 10 kg fill weight can occupy different volumes depending on the ingredient, particle size, settling and filling method. A liner also needs headspace for closing, room for a seal or tie, and enough slack to sit within its outer bag without overstressing corners.
Begin with measured filled volume. For a preliminary calculation, volume in litres equals mass in kilograms divided by measured bulk density in kilograms per litre. If an illustrative ingredient has a bulk density of 0.55 kg/L, 10 kg occupies approximately 18.2 L before allowances for headspace and pack geometry. This 0.55 value is a hypothetical example, not a property of Biolastic film or of all flour. Measure your own ingredient over representative lots.
A 25 kg bag should not simply be specified by multiplying the dimensions of a 5 kg bag by five. Outer-sack dimensions, stacking shape, filling spout, sealing position and how the powder settles can change the best width-to-length ratio.
Fill the intended outer sack with the actual ingredient using the normal line. Record the settled width, depth and height. Note whether the liner must fold over the sack lip during filling, whether a gusset is needed and how much material is required above the powder for closure. Record the flat empty liner width, length and gusset separately from the filled dimensions.
For a simple flat tube, layflat width is half the flattened circumference, not the diameter of the filled bag. A gusseted construction changes the relationship. Ask the converter for a drawing showing layflat width, total length, side or bottom gusset, seal placement and dimensional tolerance. Approve a physical sample inside the real outer sack before ordering volume.
Use three sample sizes only as a test matrix—5, 10 and 25 kg—and approve each separately. If your bakery premix contains fat, salt, spices or other additives, the pack trial must reflect that formula rather than plain flour alone.
Dry powder packaging is frequently about controlling moisture ingress during the intended storage period. A film can be compostable and still have insufficient water-vapour resistance for a particular ingredient, climate or shelf-life target. Conversely, a barrier claim without test conditions is hard to interpret. Ask for water-vapour transmission rate data for the exact film structure, with temperature, relative humidity, method and units stated.
Siliguri and North Bengal buyers should include their actual monsoon-season storage and transport conditions in the validation plan. For international trade, test the expected warehouse, container and destination conditions rather than assuming a laboratory figure predicts every route. Assess moisture uptake, lumping, free-flow behaviour, odour changes and any product-specific safety or quality criteria. Shelf-life approval belongs to the food business operator and its competent testing partners, not to a generic bag description.
A moisture-sensitive ingredient may require a different construction or additional protective outer packaging. Do not promise that a compostable liner is a drop-in replacement for a conventional high-barrier laminate until the finished system passes trials.
Flour dust can collect in the seal area. That can create weak or intermittent seals even if the clean film seals well in a demonstration. Evaluate the actual sealing process with powder present at representative levels, not only pristine empty samples. Record sealing temperature, dwell time, pressure, jaw geometry, cooling and operator variation. The correct settings depend on the actual film and equipment.
A useful trial examines seal continuity, opening during handling, pinholes and leaks after filling. Define acceptance criteria in advance. Where a heat seal is unsuitable or not available, ask whether an approved alternative closure is feasible and whether it preserves the required barrier. A tied neck, for example, should not automatically be treated as equivalent to a validated hermetic seal.
If the line uses a vertical form-fill-seal system, confirm unwind direction, web tracking, coefficient of friction, registration requirements and whether the film format is compatible. For pre-made liners, confirm how operators place the liner in the sack and keep the sealing zone clean.
For India, the FSSAI Food Safety and Standards (Packaging) Regulations, 2018 and amendment register are central references for food-contact suitability. The official register includes amendments through 7 August 2026. Buyers should review the consolidated requirements and applicable changes with their compliance team, especially when the liner directly touches flour. Request appropriate conformity evidence for the exact contact layer and intended use.
ISO 17088:2021 addresses organic recycling of compostable plastics, including disintegration, aerobic biodegradation, effects on compost organisms and constituent controls. ISO states that it does not establish behaviour as litter or suitability for small-scale home composting. A reference to ISO 17088 does not establish food-contact safety, barrier performance or that municipal composting facilities accept a particular package. Ask for the relevant certificate, scope, validity and finished-product identification; do not treat a resin supplier's claim as automatic certification of a printed or converted liner.
For buyers in the EU or elsewhere, local food-contact and packaging obligations must be assessed separately. Never claim universal export compliance from a single Indian test report.
Compare offers using the same finished packing specification. Record unit liner mass, film and closure costs, filling throughput, rejected seals, punctures, storage failures, outer-sack compatibility, freight and taxes. The most useful metric is total relevant packaging and failure cost divided by accepted kilograms shipped.
For an illustrative comparison, suppose 1,000 ten-kilogram packs are attempted and 20 fail inspection. If the relevant packing spend is ₹18,000, the cost per accepted pack is ₹18,000 ÷ 980 = about ₹18.37; per accepted kilogram it is about ₹1.84. These are fictional arithmetic inputs, not Biolastic prices, reject rates or performance results. The same approach works in any currency.
For liners purchased by weight, measure actual average bag mass rather than assuming a nominal micron yields an exact count. For an approximate flat film layer, mass in kilograms equals area in square metres multiplied by thickness in microns multiplied by density in g/cm³, divided by 1,000. Include both walls of a tube, gussets and seal trim. Actual construction and density must be confirmed.
First, document the ingredient and intended use: flour type, additives, moisture target, storage duration, outer sack, fill weight and line speed. Second, request the liner drawing and material identification. Third, collect representative samples and the documents relevant to the intended food-contact and compostability claims.
Run consecutive fills on the actual equipment. Inspect film tracking, powder spillage, static, seal contamination, closure quality and cycle time. Measure packed dimensions and stack behaviour. Then hold samples under agreed storage and transport conditions, examining moisture changes, seal integrity, pinholes, odour and caking. Keep results traceable to the film lot, ingredient lot and machine settings.
Use written acceptance criteria. A supplier sample that passes one attractive demonstration is not equivalent to a qualified production material. If the results are mixed, isolate the cause before increasing thickness or changing film: the problem may be filling geometry, sharp sack edges, seal contamination or unsuitable warehouse conditions.
An enquiry should state the ingredient, whether the liner directly contacts food, the nominal fill weight (5, 10 or 25 kg), measured bulk density, intended outer sack and finished pack dimensions. Include current liner drawing or photos, closure method, equipment, monthly consumption, destination, storage duration and any documented barrier or regulatory requirements.
Ask the supplier to confirm feasible dimensions, film construction, thickness range, tolerances, sample process, supporting documentation, MOQ with unit, lead time and commercial terms. Clarify whether printing or customisation is feasible; do not assume it is included. If an overseas destination is involved, request written confirmation of export feasibility and destination-specific compliance responsibilities.
Send Biolastic your flour liner specifications and request a technical wholesale quotation. Include a photo of the filled outer sack and details of your sealing process. That will make the first conversation substantially more productive.
Not necessarily. Bulk density, flow, additives and closing headspace can differ. Validate each ingredient in the intended outer sack.
No. Capacity labels are application categories, not strength ratings. Film construction, thickness, handling and outer packaging determine performance.
No. Request water-vapour barrier data and test the filled product under realistic storage conditions.
No. Compostability and food-contact suitability are different assessments requiring their own evidence.
Possibly, subject to the actual film and equipment. Test tracking, sealing, friction and filling speed before ordering production quantities.
Powder in the seal area, unsuitable machine settings, film mismatch or inconsistent pressure can contribute. Diagnose with controlled trials.
The catalogue invites specification-led enquiries, but manufacturing feasibility, price, lead time and export availability require written confirmation.
State ingredient, fill weight, bulk density, outer sack, dimensions, machine, monthly quantity, destination and required documents.
Biolastic product reference: Compostable Flour & Dry Food Ingredient Liner Bags. Regulatory source: FSSAI packaging amendment register and FSSAI packaging regulations text. Environmental standard: ISO 17088:2021. All arithmetic examples are illustrative; no catalogue price, guaranteed specification, certification, stock position or export service is asserted.
Not necessarily. Bulk density, flow, additives and closure headspace differ; validate each ingredient in the intended outer sack.
No. Capacity labels are not strength ratings. Construction, handling and outer packaging affect performance.
No. Request water-vapour barrier data and test the filled product under realistic storage conditions.
No. Compostability and food-contact suitability require separate evidence.
Only after testing the actual film and equipment for tracking, friction, sealing and throughput.
Powder contamination, unsuitable settings, material mismatch and inconsistent sealing pressure can contribute.
Feasibility, pricing, lead time and export availability must be confirmed in writing.
Ingredient, fill weight, measured bulk density, outer sack, dimensions, equipment, monthly volume, destination and required documents.
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