Common Laminated Glass Defects and How to Avoid Them

Laminated glass is a critical component in architecture and automotive applications where safety, acoustics, and structural integrity are essential. However, defects, whether due to raw materials, process parameters, or post-installation exposure, can compromise product performance, drive up warranty claims, and damage customer trust.

This guide outlines key laminated glass defects, their root causes, and practical, process-level prevention strategies to help you ensure consistent quality and reduce rework or field failures.

Understanding Laminated Glass and Its Applications

Laminated glass is created by bonding layers of glass with resin interlayers, such as polyvinyl butyral (PVB) or ethylene vinyl acetate (EVA), resulting in a composite that holds together when shattered. This construction improves safety by preventing shards from dispersing and offers enhanced sound insulation and UV protection.

It’s widely used in building facades, automotive windshields, overhead glazing, interior walls, and skylights, anywhere safety, visual clarity, and acoustic performance are important. Because these applications are often exposed to mechanical stress, temperature shifts, or weather, maintaining laminated glass quality is critical to long-term reliability and appearance.

Read: Exploring What Laminated Glass Is Used for and Its Benefits

Laminated Glass Defects and How to Prevent Them

Defects in laminated glass can arise from various factors, including manufacturing processes, environmental exposure, and material incompatibilities. Identifying these defects and implementing preventive measures can significantly enhance the durability and performance of laminated glass:

1. Air Bubbles

Air bubbles are trapped pockets of air or moisture between the glass and interlayer. They usually appear when de-airing is incomplete or when moisture-laden PVB is used. Bubbles reduce optical quality and may weaken the bond over time, especially in load-bearing or visible applications.

How to Prevent It

Use properly conditioned interlayers. PVB should have a moisture content below 0.5%. Ensure vacuum de-airing or nip rolling is effective before autoclaving. Surface cleanliness is also critical; even small particulates can disrupt bonding and allow air gaps.

2. Delamination

Delamination happens when the bond between glass and interlayer begins to separate, often starting at the edges. It’s commonly caused by moisture infiltration, undercuring in the autoclave, or using incompatible sealants with PVB or EVA.

How to Prevent It

Apply sealants that are chemically compatible with the interlayer and follow full autoclave cycles tailored to the glass size and thickness. Avoid shortcuts in curing time or ramp rates. Store laminated units in climate-controlled environments to prevent early-stage moisture exposure.

3. UV-Induced Yellowing

Discoloration of the interlayer is usually caused by UV degradation. Over time, this reduces clarity and can indicate that the laminate’s protective barrier is breaking down. This is a concern for facades, skylights, or canopies with prolonged sun exposure.

How to Prevent It

Use UV-stabilized PVB or EVA, and consider low-iron glass with integrated UV filters when clarity is critical. Protective exterior coatings or films can further slow down degradation, especially in sun-intense climates like Florida or the Southwest.

4. Edge Seal Failure

A failed edge seal lets moisture and air infiltrate the laminate, accelerating delamination and discoloration. This usually stems from poor sealant application, improper cure, or sealant-glass incompatibility. Cleaning agents used near edges can also weaken seals over time.

How to Prevent It

Use sealants tested for long-term durability with your interlayer material and confirm full bond contact along the perimeter. Avoid applying sealants on contaminated surfaces and allow adequate curing. Periodic adhesion testing or visual edge checks during QC can catch early failures.

5. Thermal Stress Cracks

These cracks result from rapid or uneven heating across the glass surface. For example, when part of a window is shaded and part is in full sun. Standard annealed glass is especially vulnerable when installed in areas with strong solar exposure or close-range HVAC vents.

How to Prevent It

Specify heat-strengthened or tempered glass for thermally exposed applications. Account for shading patterns and air flow during architectural planning. Ensure that expansion gaps and mounting tolerances are correctly implemented to relieve thermal stress buildup.

6. Inclusion of Foreign Particles

Small particles like dust, fibers, or metal fragments can become embedded during lamination. These inclusions not only look unprofessional but can create weak spots that lead to cracking or delamination under pressure or over time.

How to Prevent It

Maintain cleanroom-like conditions in the lamination zone, or at minimum, follow strict cleaning protocols. Clean all surfaces just prior to assembly, use lint-free gloves, and inspect every glass/interlayer set under proper lighting before pressing.

7. Uneven Interlayer Thickness

Variations in interlayer thickness can lead to localized distortion, poor bonding, and stress concentration. This typically occurs when interlayers are wrinkled, misaligned, or pressed under non-uniform pressure or temperature.

How to Prevent It

Store interlayers flat and at stable humidity, typically 20–30%. During assembly, ensure consistent layup without folds or misalignment. Lamination equipment must be calibrated to deliver uniform pressure and heat across the entire glass area.

8. Improper Curing

Improper curing during autoclaving results in tacky interlayers, poor optical clarity, and weak adhesion. Common causes include incorrect temperature, inadequate pressure, or shortened hold times, especially when cycles are rushed to increase output.

How to Prevent It

Adhere strictly to the interlayer manufacturer’s curing recommendations. Monitor time, temperature, and pressure throughout every cycle, and use automated logging when available. When glass sizes or stack configurations change, validate the process with test runs before releasing to production.