Steve, I am employed at a facility that manufactures PVB film for laminated glass.

We distinguish between three different surface roughness types: RzN, RzV, and RzR. Each roughness type has a specific surface structure and functional purpose within the lamination process.

RzN (Normal / Neutral Roughness) RzN represents the standard or reference surface roughness. It is characterized by a uniform, evenly distributed micro-texture without a preferred direction. This roughness provides a balanced combination of good glass adhesion, optical quality, and stable lamination behavior, and is commonly used as the baseline for comparison.

RzV (Increased / Coarse Roughness) RzV features a more pronounced surface structure with higher peak-to-valley values. The rougher texture improves air evacuation during lamination and increases process robustness, particularly for large glass panels or more demanding lamination conditions. This type may have a minor impact on optical clarity but offers advantages in processing reliability.

RzR (Directional Roughness) RzR is a direction-dependent roughness created by the manufacturing or rolling process. The surface exhibits a distinct orientation, resulting in different roughness values in the machine direction (MD) and cross direction (CD). This controlled directional structure supports guided air flow and influences material behavior during heating and pressing. Measurements of RzR are therefore sensitive to the measurement direction.

In summary, RzN provides a uniform reference surface, RzV enhances air removal through increased roughness, and RzR introduces controlled, directional surface features to influence lamination behavior.

1. RzN – Normal/Neutral Roughness

RzN is the standard or reference roughness.

Characteristics

Evenly distributed micro-peaks and valleys

Relatively isotropic structure (no clear preferred direction)

Moderate roughness value

Function

Good balance between:

adhesion between glass and PVB

optical quality

Stable behavior during lamination

Usually used as a baseline for comparisons

Application

Standard PVB film

Common applications in laminated safety glass

1. RzV – Raised/Coarse Roughness

RzV stands for a raised or roughened surface.

Features

Higher peak-to-valley heights (higher Rz value)

More pronounced microstructure

Often a slightly more aggressive profile

Function

Improved:

ventilation during lamination

processability with thicker or larger glass panes

Less chance of air inclusions

Disadvantages

Light can affect:

optical clarity

surface uniformity

Applications

Large panes

Complex lamination processes

Situations where process reliability is more important than maximum optical clarity

1. RzR – Directional Roughness

RzR is a directionally determined roughness, resulting from the production or rolling process.

Features

Microstructure with a clear preferred direction

Roughness values ​​differ in:

machine direction (MD)

transverse direction (CD)

Often fine rib or line structures

Function

Controlled:

Air conduction

Material behavior during heating and pressing

Can influence lamination behavior

Important considerations

Measurements are direction-sensitive

Measurement results vary depending on the measurement direction

Application

Specific production settings

Process optimization

Situations where controlled flow is required