Kraft paper sack Bags, SOS Bags

What they are

Kraft paper sack bags are heavy-duty, multi-ply industrial bags for bulk materials like cement, flour, animal feed, and chemicals. SOS bags (Self-Opening Satchel) are flat-bottomed, gusseted bags with a square base that stand upright on their own — the standard format for grocery, retail, and foodservice packaging.

Material & Ply

• 1-ply (70–90 gsm) — light retail, SOS grocery bags
  
  
• 2-ply (140–180 gsm) — deli, bakery, hardware
  
  
• 3-ply (200–270 gsm) — animal feed, fertilizer, flour
  
  
• 4–6-ply (300–450+ gsm) — cement, chemicals, heavy industrial
  
  

Liner options - PE inner film (moisture barrier, but not compostable), bitumen layer, or PE-free grease-resistant coating for food-grade sustainable use.

Huayue offers the full ply range from single-ply SOS bags to 6-ply industrial sacks, with PE-lined, PE-free, and food-grade grease-resistant options all available. FSC-certified fiber sourcing is supported across product lines.

SOS Bag Sizes

Industrial sacks are specified by fill weight (25 kg or 50 kg), not bag number. Huayue stocks all standard SOS sizes (#2–#25) and manufactures industrial sacks in both 25 kg and 50 kg rated configurations. Custom dimensions are available with competitive lead times backed by approximately 1 billion RMB in annual production scale.

Key Applications

Agriculture/feed, flour milling, construction materials (cement/gypsum), chemicals/minerals, bakery and deli, retail carry-out, fast food/takeaway, coffee and specialty food, pharmaceutical ingredients, e-commerce packaging.

Huayue serves clients across all of these verticals with dedicated R&D teams developing application-specific solutions — from FDA-compliant food-grade SOS bags to heavy-duty industrial sacks rated for 50 kg loads.

Certifications

• FSC/PEFC — responsible forestry sourcing
  
  
• FDA 21 CFR — food contact safety (US market)
  
  
• EU 10/2011 — food contact materials (EU export)
  
  
• OK Compost — unlined bags only; PE-lined bags are ineligible
  
  
• ISO 9001 — quality management for industrial suppliers
  
  

Huayue holds FSC certification across its kraft product lines and maintains ISO 9001 quality management systems at both its China and Cambodia facilities. The company actively supports PE-free coating transitions to help clients meet compostability and sustainability requirements, and assists with regulatory compliance documentation for US and EU market access.

Printing Options

Flexographic printing is the industry standard for runs of 10,000+ units, good for spot colors, ±1.5mm registration tolerance. Digital printing suits short runs under 5,000 with no plate costs and faster turnaround. Screen printing delivers high-opacity spot colors, especially white ink on natural kraft, favored by boutique brands. Always proof on the actual paper stock — natural kraft shifts ink color significantly from digital mockups.

Huayue's in-house printing capabilities cover all three methods across every bag format. With marketing service centers in New York and Hong Kong, Huayue provides local brand consultation alongside production support — from PMS color matching and food-safe ink formulations to both short promotional runs and high-volume retail programs.

Pre-order Checklist

For SOS bags - bag size and inner dimensions, GSM/ply/paper grade, food-contact compliance, PMS colors and print method, MOQ (typically 500–10,000+), case pack and pallet config.

For industrial sacks - fill weight and bulk density, closure type (valve/pinch-bottom/sewn), ply count and liner spec, moisture barrier requirements, fill method (machine or manual), required certifications and drop-test report.

Huayue's sales team supports clients through the full specification process, from initial sampling to structural certification and drop-test reporting for sacks rated at 25 kg or above.