Industry Knowledge

Insulating glass (IG) units play a critical role in modern architectural glazing, providing superior insulation, energy efficiency, and long-term durability. However, one of the most common failures during production and installation is sealant leakage. Sealant overflow, uneven sealing, or weak bonding not only affects the appearance of IG units but also leads to reduced performance, moisture penetration, and early failure.

This article explains why sealant leakage happens, the engineering causes, and the practical solutions—including automated equipment that can significantly reduce human error and improve sealing consistency.

1. What Is Sealant Leakage in IG Units?

Sealant leakage refers to the uncontrolled overflow or insufficient bonding of primary or secondary sealants (such as butyl, polysulfide, silicone, or polyurethane).
This problem typically occurs during:

• Spacer sealing

• Dual-seal application

• Pressing in the IG assembly process

• Long-term service under UV or temperature cycling

If not addressed, leakage causes:

• Fogging or condensation

• Loss of insulation performance

• Edge defects

• Reduced IG lifespan

2. Main Causes of IG Sealant Leakage

2.1 Improper Butyl Application

The butyl seal is the first defense against moisture vapor. Problems arise when:

• Temperature of butyl extruder is unstable

• Pressure is too high/low

• Coating thickness is inconsistent

Result:
Sealant extrusion becomes uneven, causing gaps or overflow during pressing.

Solution:
Use a stable Automatic Insulating Glass Butyl Extruder for accurate temperature and pressure control.

2.2 Spacer Frame Deformation

If the spacer frame is not straight or has irregular corners:

• Sealant cannot fill gaps properly

• Pressing machine cannot achieve uniform pressure

Result:
Leakage appears along weak edges.

Solution:
Use a high-precision Automatic Spacer Bending Machine to ensure perfect 90° and 135° corners.

2.3 Poor Pressing Accuracy

If the IG pressing section cannot maintain stable pressure or alignment:

• Butyl is squeezed out unevenly

• The secondary seal cannot form a complete bonding line

Main reasons:

• Pressing plates not parallel

• Air-suction not sufficient

• Glass thickness mismatch

Solution:
Use an Automatic IG Production Line with Servo Pressing System for accurate control.

2.4 Incorrect Secondary Sealant Mixing

Two-component sealants (such as silicone or polysulfide) require precise ratio mixing.

Problems come from:

• Incorrect A/B ratio

• Clogged mixer

• Unstable pump pressure

Result:
Sealant becomes too soft, too hard, or unbonded — leading to leakage over time.

Solution:
Upgrade to an Automatic Two-Component Sealant Extruder for accurate mixing.

2.5 Poor Environmental Conditions

During sealing:

• Temperature below 10°C

• Humidity too high

• Dust contamination

• Oil or fingerprints on glass edges

These all reduce adhesion quality.

Solution:
Ensure cleanroom standards and proper temperature control.

2.6 Operator Mistakes

Manual sealing or untrained operators often cause:

• Over-extrusion

• Sealant gaps

• Uneven sealing speed

• Wrong sealant type

Solution:
Introduce automation to reduce human variability.

3. Solutions to Prevent IG Sealant Leakage

✔ Use Intelligent IG Production Equipment

Automated systems improve:

• Sealant uniformity

• Ratio mixing accuracy

• Pressing pressure control

• Production stability

Recommended machines (with internal links below):

• Automatic Butyl Extruder Machine

• Automatic Spacer Bending Machine

• Vertical IG Production Line with Servo Pressing

• Automatic Two-Component Sealant Extruder

✔ Maintain Equipment Regularly

Regular maintenance prevents pressure loss, temperature issues, and mixer blockage.

✔ Use Compatible Sealants

Ensure sealant type matches the IG process and regional climate requirements.

✔ Strengthen Quality Inspection

Inspection points:

• Butyl continuity

• Spacer alignment

• Secondary seal uniformity

• Pressing plate parallelism

• Moisture vapor transmission testing

4. Recommended Equipment (Internal Links)

以下内链格式可直接使用：

• Automatic Butyl Extruder Machine
  https://www.eastglassmachine.com/products/butyl-extruder

• Automatic Spacer Bending Machine
  https://www.eastglassmachine.com/products/spacer-bending-machine

• Vertical Automatic Insulating Glass Production Line
  https://www.eastglassmachine.com/products/insulating-glass-production-line

• Two-Component Sealant Extruder
  https://www.eastglassmachine.com/products/sealant-extruder

5. Conclusion

Sealant leakage in IG units is preventable. By using stable automated equipment, maintaining proper production parameters, and ensuring correct sealing techniques, manufacturers can significantly reduce leakage issues and extend the service life of insulating glass units.

Reliable sealing is essential not only for product quality but also for the long-term energy performance of modern glazing systems.