Liner bags are the unglamorous product that quietly decides whether your inner packing works. A chemical distributor in Georgia, a food ingredient blender in Illinois and a textile exporter all buy essentially the same thing: a clean polyethylene tube that protects product from the outer world and the outer world from the product. We extrude and convert liner bags in transparent and coloured grades, and after years of spec calls with US buyers, the same handful of decisions keeps coming up. Here they are, in the order that matters.
Thickness is the whole conversation
Liner film runs 1.5 to 6 mil depending on duty. The common failure mode is buying thin to save cents and paying for it in pins and splits at the bottom seal. Our working guide:
| Application | Recommended thickness | Indicative FOB (each) |
|---|---|---|
| Textiles, apparel, light goods | 1.5 - 2 mil | $0.08 - $0.12 |
| Powders inside woven sacks | 2 - 3 mil | $0.10 - $0.16 |
| Chemicals, sharp granules | 3 - 4 mil | $0.14 - $0.22 |
| Heavy industrial, drum liners | 4 - 6 mil | $0.20 - $0.34 |
Gusseted bodies sit square inside cartons and drums; flat tubes suit sack lining and irregular fills. Bottom options are flat seal for liquids retention or folded-star seal for point loads, and we recommend the latter whenever product has edges.
Transparent or coloured: it is a system decision
Transparent liners let QC see product without opening anything, which is why food and pharma buyers default there. Colour earns its keep as a coding system: blue for one chemical grade, red for another, so floor crews catch a mis-slotted bag before it ships. Colour also hides product in retail-adjacent warehousing. Both run on the same extruders; colour masterbatch adds a small premium and slightly longer changeover, reflected in lead time on first orders only.
Compliance and cleanliness
For food contact, virgin LDPE or LLDPE compliant with FDA 21 CFR 177.1520 is the baseline, with lot-level certificates of analysis supplied per shipment. For chemicals, tell us the product family; some solvents and oils need specific resins or coex structures rather than generic LDPE. Cleanliness standards matter as much as resin: liners for food grade run in dedicated production windows with documented handling, which is worth asking any supplier to state on paper.
Bulk economics
Liners cube beautifully: a 40-ft high cube carries enormous unit counts, frequently over half a million light-gauge liners, which is why freight barely registers in landed cost. Production is 2 to 3 weeks for standard sizes; custom gussets and prints run 3 to 4 weeks. Ocean transit adds 4 to 6 weeks to the US coasts, and samples ship by air inside a week for line trials.
Quick answers
Do coloured liners fade in warehouse light?
Masterbatch colours are stable for normal indoor exposure; extended sun requires UV packages, which we add when the application calls for it.
Can liners be printed?
Yes, up to flexo print for handling instructions, lot grids or logos. Print on liners is more common than buyers expect once compliance labeling gets involved.
Size ranges and options are on the Liner Bags page. For liners inside bulk bags, see the FIBC liners guide, and for outer packaging the PP woven sacks guide.
