Filling High-Viscosity Cosmetics: How to Prevent Air Bubbles and Stringing

For cosmetic formulators, high viscosity often equals high quality. Rich night creams, thick clay masks, and medicinal ointments convey luxury and potency. But for the process engineer on the packaging line, "thick" means trouble.

Handling high-viscosity products presents two major challenges: Air Bubbles (which cause weight inconsistencies and messy "burping" by the consumer) and Stringing (which contaminates the seal area, causing leaks).

If your production line is struggling with these issues, the problem likely lies in the filling dynamics. At Wenzhou Kxite Machinery, we engineer our Tube Filling Sealing Machines with specific technologies to master the physics of thick liquids.

1. The Problem: Stringing & Dripping

Scenario: You are filling high viscosity ointment. The filling nozzle lifts up after the dose, but a thin "string" of product trails behind, like mozzarella cheese on a pizza. This string falls onto the tube's sealing area. When the hot air or folding station tries to seal the tube, that product residue prevents a hermetic bond, leading to leaks.

The Solution: The "Blow-Cut" Mechanism

Standard shut-off nozzles often fail to break the surface tension of sticky products. To solve this, the Kxite NF-120 utilizes a specialized Blow-cut filling mechanism.

• How it works: At the precise moment the filling cycle ends, a calibrated pulse of compressed air is shot through the nozzle tip.
• The Result: This air pulse instantly severs the product stream, forcing the "string" down into the tube and leaving the nozzle tip clean. It acts as a highly effective anti-drip nozzle for tube filler applications, ensuring the sealing area remains 100% contaminant-free.

2. The Problem: Air Bubbles (Pocketing)

Scenario: You are filling a thick face wash. The nozzle sits at the top of the tube and drops the product in. Because the product is too thick to flow to the bottom, it piles up, trapping a large pocket of air underneath. When the consumer squeezes the tube, it makes an embarrassing splattering sound.

The Solution: "Tube Descends While Filling" (Bottom-Up Filling)

To involve preventing air bubbles in lotion tubes, you must eliminate the gap between the product and the tube bottom.

• The Technology: The Kxite NF-120 features a servo-driven lifting mechanism. Before filling starts, the empty tube is lifted up so the nozzle reaches the very bottom.
• The Process: As filling begins, the tube slowly descends in perfect synchronization with the filling speed. The nozzle tip stays just below the surface of the rising product level.
• The Result: The product is laid down smoothly from the bottom up, pushing the air out naturally. This guarantees accurate weight and a premium, bubble-free user experience.

3. Bonus Tip: Temperature & Viscosity Management

Even with the best machinery, some products are simply too thick to pump at room temperature. For products like petroleum jelly or heavy waxes, we recommend equipping your Tube Filling Sealing Machines with a jacketed hopper and an agitator.

By heating the product slightly (e.g., to 35-40°C), you reduce the viscosity just enough to improve flow without compromising the formula's stability, making the Blow-Cut and Bottom-Up filling even more effective.

Conclusion

High-viscosity products demand high-precision machinery. You shouldn't have to choose between a rich product formula and a secure package seal.

At Kxite Machinery, our NF-120 series is purpose-built for the most challenging textures in the cosmetic and pharma industries. With features like the pneumatic Blow-Cut nozzle and synchronized tube descent, we ensure every tube is filled cleanly, accurately, and without bubbles.