Sewn open mouth bags

Buyers should prioritize Multi-wall Kraft Paper (typically 2 to 4 layers) or Woven Polypropylene (PP) depending on the product weight. For moisture-sensitive goods, ensure the inclusion of a PE (Polyethylene) liner or a laminated inner layer. The GSM (Grams per Square Meter) is a critical indicator of strength; for heavy-duty industrial use, a total paper weight of 70-80g per ply is standard.

The bottom of the bag must feature reinforced chain stitching or lock stitching to prevent leakage. For fine powders, a filter cord (filler cord) should be sewn into the seam to seal needle holes. If the bags are used for food or chemicals, verify that the sewing thread is high-tenacity polyester and that the crepe tape used for reinforcement is of high quality to prevent tearing at the stress points.

For food-grade applications, suppliers must provide FDA or EC 1935/2004 compliance certifications. If transporting hazardous materials, the bags must meet UN Certification (UN Rating) for dangerous goods. Additionally, ensure the manufacturer follows ISO 9001:2015 for quality management and ISO 21898 for heavy-duty packaging specifications.

Request a Drop Test Report (usually from a height of 1.2 to 1.8 meters) to ensure the seams do not burst upon impact. You should also verify the Safe Working Load (SWL), which typically ranges from 10kg to 50kg for SOM bags. For outdoor storage, confirm the presence of UV stabilizers in PP woven bags to prevent degradation from sunlight.

Always utilize Third-Party Inspection services (such as SGS or Intertek) to conduct a Pre-Shipment Inspection (PSI). Focus on checking the stitching density (number of stitches per 10cm) and dimensional accuracy. On Made-in-China.com, prioritize Audited Suppliers who have undergone comprehensive on-site factory verifications to ensure their production capacity matches your order volume.

Price is heavily influenced by raw material fluctuations (paper pulp or PP resin). Negotiate a formula-based pricing model for long-term contracts. For MOQ (Minimum Order Quantity), standard custom-printed bags usually require 5,000 to 10,000 units. To reduce costs, suggest using standardized bag sizes already in the supplier's production line, which can lower the MOQ and unit price by 10-15%.

SOM bags are bulky; therefore, palletization with shrink-wrapping is essential to prevent moisture absorption and shifting during sea transit. Ensure the supplier uses desiccants inside the container if shipping through humid tropical zones. Clarify Incoterms clearly; FOB (Free On Board) is generally preferred for buyers who have their own freight forwarders to better control shipping timelines and costs.

Use Secured Payment services provided by Made-in-China.com to ensure that funds are only released to the supplier after you confirm receipt of goods or after the bill of lading is issued. Avoid direct wire transfers to private accounts; always ensure the beneficiary name matches the company name on the business license and the audited profile.