White-coated woven bags with square bottom and valve opening | Standard single-color printing, economical model | Compatible with automatic filling, leak-proof and dustproof

This product is a woven bag with a square bottom and valve closure, featuring an economical single‑color print design. It is specifically engineered for high‑volume, automated filling of powdered construction materials such as whitewash. The square‑bottom valve design is compatible with high‑speed valve‑filling machines, delivering excellent filling efficiency while minimizing dust spillage. Standard monochrome printing meets basic labeling requirements, helping to keep packaging costs under control. Ideal for manufacturers of powdered products like tree whitewash, lime powder, and calcium powder, as well as for agricultural‑input and building‑materials wholesale channels.

Applicable Materials 
Tree whitewash, lime powder, calcium powder, putty powder, gypsum powder, cement, dry-mix mortar, talc powder, heavy calcium carbonate powder, light calcium carbonate powder, and other powdered construction materials.

Core Advantages

Automatic filling with a square-bottom valve opening 
The square-bottom valve‑mouth design is specifically engineered for high‑speed valve‑mouth filling machines. During filling, the discharge nozzle inserts into the valve mouth, and the product flows through a sealed channel into the bag; once filling is complete, the valve mouth automatically closes. Single‑bag filling takes 6 to 10 seconds, delivering 2 to 3 times the efficiency of manual filling.

Leak-proof and dustproof 
During valve‑port filling, the product flows through a sealed channel between the filling nozzle and the valve port, reducing dust spillage by more than 80% compared with manual filling. The self‑sealing valve design, combined with heat‑seal bottom technology, ensures that the bag body is free of pinholes and seams, preventing powder leakage and dust generation during transportation and stacking.

Economy monochrome printing 
It employs conventional gravure printing in a single color, producing simple yet crisp designs. With low plate‑making costs, it significantly reduces upfront investment. This solution is ideal for coating‑agent manufacturers that require large‑volume procurement, have modest packaging‑appearance expectations, and prioritize cost control.

Stable stacking with square bases 
The base features a square, three-dimensional structure; once filled, the pouch maintains a crisp, straight shape and stands stably. When stacked on pallets, it distributes weight evenly, resisting tilting or collapse and maximizing warehouse space utilization.

Comparison between a square-bottom valve mouth and a flat pouch 
Square-bottom valve bags are compatible with automatic filling machines, delivering a filling speed of 6 to 10 seconds per bag and reducing dust spillage by 80%. After filling, the valve seal self‑closes, eliminating the need for manual sealing. These bags offer stable stacking on pallets with a high number of layers. Although the unit cost is slightly higher, labor costs are significantly reduced, making them ideal for large‑scale enterprises with high daily output and automated filling lines.

Flat‑bottom pouches are suitable for manual or semi‑automatic filling, with a filling speed of 15 to 30 seconds per bag. Dust spillage is relatively high, so the bags must be sewn and sealed after filling. Palletizing stability is moderate, and the unit cost is low, making this option ideal for small‑batch production or manual filling lines.

Leak-proof and dust-proof design details 
The valve opening measures 80 to 120 mm in length, with a diameter customized to match the filling machine’s discharge nozzle, ensuring a tight seal and zero leakage during filling. The valve can be configured as either a center‑mounted or an eccentric design, integrally molded with the bag body to eliminate the risk of delamination or detachment. Once filling is complete, the discharge nozzle retracts, and the valve automatically closes under the pressure of the product inside the bag and by virtue of its own structure—no additional manual intervention is required. The bottom is sealed using a heat‑sealing process, providing a fully airtight seal with no pinholes; even when filled with powdered materials and inverted, it remains leak‑proof.

Material and Craftsmanship 
The outer layer is made of PP polypropylene woven fabric, with a basis weight customized to meet load‑bearing requirements. The bag style is a square‑bottom valve pouch, featuring a three‑dimensional, square-shaped bottom and an integrated cuff‑style valve opening. Printing is standard gravure, in a single color. The bottom is heat‑sealed.

Tensile strength 
Testing has shown that the tensile strength exceeds 650 newtons per 50 millimeters, enabling it to support 10 to 25 kilograms of whitewash.

Packaging drop test 
Under a 25-kg load condition, following a 1.2-meter free-fall test, the product remained intact and showed no leakage after being dropped from all six sides.

Applicable filling method 
Compatible with impeller‑type, screw‑type, and pneumatic valve‑mouth filling machines. Customers must provide the specifications of the filling machine’s discharge nozzle; the manufacturer will then customize the valve‑mouth size accordingly.

Packaging Specifications 
The loading weight can be customized to 10 kg, 15 kg, 20 kg, or 25 kg.

Customization Scope 
Dimensions can be customized to suit the weight of the material being loaded, with adjustable length, width, and base dimensions. Valve‑port specifications can be tailored to match the discharge nozzle of your filling machine, with customizable length and diameter. Printing content can be customized according to customer requirements, featuring single‑color text such as brand name, product name, net content, and more. Fabric thickness can be adjusted to meet specific weight‑per‑area needs.

Environmental Compliance 
The product is manufactured using virgin PP material and is recyclable.

Applicable Subjects 
This product is suitable for tree‑whitening agent manufacturers, lime powder processing companies, calcium powder plants, putty powder factories, dry‑mix mortar producers, agricultural‑input wholesalers, and building‑materials wholesalers.

MOQ and Price 
Negotiable