In the glass manufacturing industry, one of the most common defects encountered during production is the presence of bubbles in glass wine bottles. While glass bottles remain one of the most trusted packaging solutions for beverages and spirits due to their safety, durability, and premium appeal, defects such as bubbles can affect both product quality and customer satisfaction.
This article explores the main causes of bubble formation in glass bottles and offers insights into how to minimize them through proper process control and quality management.
1. Improper Feeding of Glass Gob into the Mold
When the molten glass gob fails to accurately enter the blank mold, excessive friction with the mold wall occurs. This creates wrinkles on the bottle surface. During the blowing process, these wrinkles expand and eventually form visible defects on the bottle body.
2. Large Shear Marks from the Feeder
If the shear blades of the feeder leave excessive scars on the glass gob, these marks will appear as defects on the finished bottle after forming.
3. Poor Mold Material Quality
Low-density or low-grade mold materials tend to oxidize quickly at high temperatures, creating tiny pits on the mold surface. This results in rough or uneven surfaces on the finished glass bottles.
4. Low-Quality Mold Oil
If the mold lubrication oil is of poor quality, lubrication becomes insufficient. This slows down the gob flow and alters its shape too quickly, leading to bottle defects.
5. Unreasonable Mold Design
If the blank mold cavity is too large or too small, the glass gob cannot spread evenly during the blowing process. This causes uneven distribution, leading to spots or black marks on the bottle body.
6. Uneven Gob Delivery and Poor Airflow Adjustment
When the gob delivery speed is unstable or the blowhead airflow is not well balanced, the temperature between blank and blow molds becomes inconsistent. This produces cold spots on the bottle surface, directly affecting its smoothness and clarity.
7. Impurities or Uneven Temperature in the Furnace
If the molten glass contains impurities or the furnace temperature is not evenly controlled, the final bottles may show bubbles, small particles, or stones, lowering the product’s overall quality.
8. Improper Machine Speed
If the forming machine speed is set too high or too low, the bottle body may become uneven, with inconsistent wall thickness, which also contributes to visible spots or bubbles.
Conclusion
Bubbles and defects in glass bottles usually result from process imbalances, equipment issues, or raw material quality. By improving mold quality, using reliable lubrication oil, optimizing gob delivery, and maintaining furnace stability, manufacturers can significantly reduce the occurrence of bubbles.
At QLT Glass Products Manufacturing Co., Ltd., we adopt strict process controls, advanced annealing technology, and precision mold maintenance to ensure every bottle meets the highest standards of clarity, safety, and strength. This is why leading wine and spirits brands worldwide trust us as their long-term glass packaging partner.
Post time: Jul-31-2025