How to Troubleshoot Leakage and Deformation in Softgel Production

Softgel leakage and deformation problems can usually be reduced by controlling gelatin properties, fill compatibility, encapsulation settings, and drying conditions. In commercial softgel manufacturing, acceptable leakage rates are often maintained below 1%, while poor process control may increase defects to 3–5%. A rotary die machine running at 2–8 rpm requires stable gelatin temperature, ribbon thickness, and sealing pressure to maintain consistent capsule quality.

Softgel defects are rarely caused by only one parameter. A capsule with leakage may involve gelatin moisture, fill composition, die pressure, or drying humidity at the same time. A structured inspection process helps manufacturers locate the source faster and reduce unnecessary batch losses.

“A small change in shell temperature, moisture content, or fill viscosity can affect capsule appearance and sealing performance.”

During gelatin preparation, the shell material must reach a suitable balance between flexibility and strength. Most softgel shells contain gelatin, purified water, and plasticizers such as glycerin or sorbitol. Gelatin concentration is commonly controlled around 35%–45%, while excessive water content can reduce shell strength after drying.

The gelatin melting stage requires stable temperature management. Many production systems maintain gelatin mass temperatures around 55–65°C. Temperatures above 70°C for long periods may affect gelatin quality and reduce film-forming ability. Vacuum deaeration is also used because trapped air may create weak areas inside the shell.

The condition of gelatin ribbons directly affects sealing performance. Rotary die encapsulation systems usually require ribbon thickness around 0.6–0.8 mm. If ribbon thickness changes by more than 10%, the sealing area may become uneven, increasing the possibility of leakage.

The next factor to review is the relationship between the fill material and gelatin shell. Softgel products may contain oils, vitamins, botanical extracts, or pharmaceutical liquids. Some ingredients can interact with gelatin and reduce shell strength during storage.

“Fill formulations containing volatile solvents or strong surfactants require compatibility checks before commercial production.”

For example, formulations containing more than 10% ethanol or similar volatile components may require additional stability testing because these ingredients can migrate into the gelatin layer. Oil-based fills usually require proper viscosity control, often between 5,000 and 20,000 cP depending on the formulation design.

A stable fill system must also maintain accurate dosing. In many commercial lines, fill weight variation is controlled within approximately ±5%. Excessive fill volume may increase pressure inside the capsule, causing seam leakage during storage or transportation.

The encapsulation stage is one of the most sensitive parts of softgel production. Modern softgel manufacturing equipment uses rotary dies to combine two gelatin ribbons around a liquid fill. The sealing process depends on die pressure, wedge temperature, ribbon alignment, and machine speed.

Low sealing pressure may create incomplete bonding between gelatin layers. Excessive pressure may force fill material into the seam area, reducing sealing strength. Manufacturers usually adjust these parameters through capsule testing and microscopic inspection of the seam.

Wedge temperature also affects capsule quality. When temperature is too low, gelatin surfaces may not fuse properly. When temperature is too high, the gelatin becomes too soft and the seam structure may become weak. A temperature difference of only 2–3°C can affect sealing consistency during long production runs.

Defect Type	Common Cause	Process Check
Seam leakage	Poor ribbon sealing or incorrect pressure	Check die pressure and wedge temperature
Surface leakage	Shell damage or air bubbles	Review gelatin preparation
Oil leakage after storage	Fill-shell interaction	Perform compatibility testing
Irregular shape	Drying imbalance or mechanical pressure	Check drying conditions

Leakage analysis should continue into the drying stage because freshly produced softgels contain high moisture levels. Newly encapsulated capsules may contain around 30%–40% water before drying. The final moisture level is commonly reduced to approximately 5%–8% depending on product requirements.

Drying conditions influence both appearance and mechanical strength. Industrial drying rooms often operate around 20–25°C with relative humidity controlled near 20%–30%. When humidity rises above 40%, drying becomes slower and capsules may remain soft or stick together.

Uneven moisture removal creates deformation problems. Capsules may become flattened, wrinkled, or misshapen when one side loses moisture faster than another. Proper airflow distribution and tray loading help maintain consistent drying.

“Softgel deformation often appears after encapsulation because moisture movement continues during drying and storage.”

The drying time depends on capsule size, shell composition, and environmental conditions. Large softgels generally require longer drying periods because thicker shells release moisture more slowly. Production records from different facilities show drying times commonly ranging from 12 to 48 hours.

Mechanical handling after drying can also affect capsule shape. Softgels with insufficient hardness may deform during polishing, inspection, or packaging. Conveyor speed, contact pressure, and storage conditions should be checked when capsules pass encapsulation inspection but fail later.

Quality inspection data provides useful information for process improvement. Automated inspection systems can evaluate capsule shape, surface defects, and leakage marks at production speeds exceeding 100,000 capsules per hour. Combining inspection results with production records helps identify repeated defect patterns.

A practical troubleshooting process usually follows several steps:

1. Collect defective capsules from different production stages.

2. Identify whether leakage started during encapsulation, drying, or handling.

3. Measure shell thickness, moisture level, capsule weight, and seam strength.

4. Review machine settings, including temperature, pressure, and speed.

5. Adjust one parameter at a time and confirm results with quality testing.

Manufacturers applying statistical process monitoring often track capsule weight variation, shell moisture, and defect percentage. Many commercial operations aim for leakage rates below 1% and maintain consistent capsule dimensions across production batches.

Preventive equipment maintenance also affects capsule quality. Rotary dies, pumps, and sealing components gradually wear during continuous operation. A production line operating several shifts per week may require regular inspection intervals to maintain accurate pressure and alignment.

The development of reliable softgel manufacturing practices depends on controlling raw materials, equipment settings, and environmental conditions together. A complete production review should include gelatin testing, fill formulation analysis, machine calibration, drying evaluation, and final product inspection.

“Reducing leakage and deformation requires stable process control from gelatin preparation to final packaging.”

Storage conditions should also be considered after production. Softgels are sensitive to temperature and humidity changes. Exposure to temperatures above 30°C or high humidity environments may soften shells, increase sticking, or affect capsule shape during shelf life.

A well-controlled softgel process combines accurate formulation design, equipment maintenance, and continuous quality checks. With proper monitoring of temperature, moisture, pressure, and drying conditions, manufacturers can maintain consistent capsule appearance and reduce production defects.