customized leather makeup bag with logo vendor

Leather cosmetic bags can be divided into the following core steps based on material properties and functional requirements:

1. Leather Pretreatment

Raw Material Grading and Batch Grouping

Raw leather is sorted by thickness, area, and degree of damage to ensure uniformity within the same batch. Top-grain leather is used for high-end bag surfaces, while split-grain leather is used for linings or accessories.

Environmentally Friendly Tanning Process

Chrome tanning or eco-tanning (formic acid + white tanning agent combination system) is used at a temperature of 40°C ± 2°C and a pH of 3.8-4.2 for 8-12 hours to enhance the leather's tear resistance. Eco-tanning requires sodium formate for alkali adjustment to control wastewater pollution.

2. Cutting and Shaping

Precision Cutting

Straight parts are cut using a hydraulic cutting machine (with an accuracy of ≤ 0.3cm). Special-shaped parts are cut using a laser (with an accuracy of ± 0.1mm). When stacking multiple layers of leather, positioning pins are used to prevent displacement.

Edge Reinforcement

The edges of the cut pieces are pre-coated with anti-fraying adhesive, and nylon reinforcing lining is laminated to key stress-bearing areas (such as the handle joints).

III. Sewing

Structural Sewing

An industrial sewing machine sews the main body with double-thread chain stitching, reducing the speed to 800 stitches per minute at corners to prevent skipped stitches. Zippers are installed using a dedicated presser foot, maintaining a 1.5mm gap between the thread and the teeth.

Functional Accessory Assembly

The magnetic clasp base is pre-punched before riveting to prevent leather cracking. The mesh interlayer in the inner pocket is ultrasonically cut to prevent snagging.

IV. Surface Finishing

Dyeing and Fatting

Dyeing with acid dyes at a constant temperature of 45°C. Fatting with synthetic oils restores the leather's softness (fatting agent dosage ≥ 8%).

Decoration

Hot Stamping: Embossing temperature 130°C ± 5°C, pressure 3.5 kg/cm² to create a three-dimensional texture. Printing: Digital printing is air-conditioned for 24 hours to set the color. Color difference ΔE ≤ 1.5.

V. Quality Control

Physical Performance Testing

Oscillatory impact test: Handle load capacity ≥ 5 kg. Zipper Durability Test: Open and close ≥ 5000 times without sticking.

Chemical Safety Testing

Free formaldehyde content ≤ 75mg/kg, heavy metal content complies with REACH standards.

VI. Packaging Specifications

Moisture-Proofing Treatment

Packaged in individual PE bags with silica gel desiccant. Moisture-proof labeling is marked on the outer box.

Warehouse Management

Shelves are kept 20cm above the ground to avoid moisture. Humidity is controlled at 45%-55%.

Processing: Exceeding the pH value during the tanning stage can cause the leather to harden; excessive hot stamping temperatures can cause leather to char. Eco-tanning wastewater must be neutralized before discharge.

(Note: Accessories include rust-proof resin-coated zippers and hardware with a coating of ≥5μm.)

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