Complete Guide to Flat Bags: Uses, Materials & Specifications
Flat bags are the simplest and most versatile plastic bag type. Without the carry handles of vest bags or the punched holes of hole punch bags, flat bags are simply an open-top pouch. This simplicity means high production efficiency, low manufacturing cost, and extreme versatility across food, hardware, agriculture, and industrial applications.
Basic Structure
Flat bags consist of two plastic film sheets heat-sealed at the bottom and sides, with an open top for filling. Optional side gussets allow the bag to expand for bulkier items.
Material Options
LDPE (Low-Density Polyethylene)
The most common flat bag material. Soft, flexible, highly transparent, excellent moisture barrier, and superior low-temperature performance. Ideal for food packaging, electronics protection, and garment storage.
HDPE (High-Density Polyethylene)
Stiffer with higher strength at the same thickness. Semi-transparent with a slight frosted appearance. Cost-effective for bulk applications like market food portioning and industrial parts packaging.
PP (Polypropylene)
Highest transparency and rigidity. Crystal-clear appearance ideal for premium display packaging of stationery, gifts, and greeting cards.
Common Sizes
Small (under 10cm width): 5x8, 6x10, 8x12cm for small parts, medicine, accessories. Medium (10-25cm): 10x15, 15x20, 20x30cm for food, hardware, stationery. Large (25cm+): 30x40, 50x70, 80x100cm for clothing, large parts, produce.
Custom sizes are available from CHIN TZON Plastics. Contact us for minimum order details.
Thickness Guide
- 1.5-2 mil: Ultra-thin for lightweight paper and simple food wrapping
- 3-4 mil: Standard for general food, snacks, small parts
- 5-6 mil: Heavy-duty for heavier goods, hardware, products needing protection
- 8-10 mil: Industrial grade for heavy parts, high-strength protection
- 12+ mil: Extra-heavy for special industrial requirements
Applications
Food Packaging: Bakery bread bags, bulk snack portioning, fresh market packaging. Food-grade flat bags use certified raw materials meeting food contact safety standards.
Industrial Packaging: Hardware screws, electronic components, auto parts all use flat bags for sorting, dust protection, and moisture prevention.
Agriculture: Seed packaging, fertilizer portioning, and produce retail with moisture and weather resistance.
Everyday Use: Seasonal clothing storage, document protection, luggage organization.
Sealing Methods
Heat sealing provides the best airtight seal for freshness and moisture protection. Twist ties work for short-term or reusable packaging. Tape sealing is simplest for temporary applications.
How to Choose
- Determine content weight, size, and properties (food-grade? sharp edges?)
- Select material (LDPE/HDPE/PP)
- Choose size (width 2-3cm wider than contents, length 3-5cm longer)
- Select thickness based on weight and protection needs
- Decide on printing requirements
CHIN TZON Plastics offers 1-3 color custom printing services. Contact us for expert packaging recommendations.
Written by CHIN TZON Plastics. Specifications and pricing subject to current quotation.