When it comes to shipping or storing bulk goods, box liners offer one of the simplest and most cost-effective ways to protect products — and your packaging. From food-grade uses to industrial parts, a well-made poly liner helps ensure cleanliness, containment, and easy transport.
What Is a Box Liner?
A box liner is a poly bag placed inside a box — typically a corrugated case — to act as a barrier between the contents and the cardboard. At M Plastics, we produce liners from LDPE blown film, custom-sized to match your box dimensions.
Liners are usually:
- Layflat or gusseted, open-top, sized to standard or custom cartons
- Bottom-sealed for strength and leak resistance
- Packed flat, ready for your packing style
Once placed in the box, the liner folds over the product and can be sealed or simply tucked in.
Why Use Box Liners?
- Product protection — blocks moisture, dust, and contamination
- Leak control — contains oils, powders, or fine particles
- Clean packaging — reduces box staining and fiber shedding from recycled cartons
- Food applications — available in FDA-grade virgin LDPE for food contact
They’re essential when packaging resins, powders, grains, meat, bakery goods, hardware, soil, rocks, and more.
How They’re Made
Because we extrude our own film, we control every variable:
- Mil thickness — matched to the load, light to heavy duty
- Opacity or tint — clear, black, or colored for batch identification
- Additives — slip, anti-static, or food-grade blends
- Size — fully customized to your carton dimensions
- Printing — warnings, barcodes, or branding on request
Who Uses Them?
Box liners are widely used by food processors, manufacturers of powders and resins, agricultural and landscaping suppliers, fulfillment centers, and hardware or construction goods packagers. In longer transit or storage, liners cut down on scrap, repackaging, and damage.
Final Thoughts
Box liners seem like a small detail, but they play a big role in protecting your product and keeping packaging clean. We work with clients to size liners properly, pick the right mil thickness, and match them to hand or automated packing. For a deeper look, see our post on box liners in industrial packaging.
If your products ship in boxes, request a quote — the right liner saves time and protects what matters.
Have a Packaging Question?
M Plastics manufactures LDPE bags and film in Los Angeles with in-house extrusion and printing. Tell us what you're packaging and we'll help you spec the right bag.
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