Visual Quality Inspection Guidelines for Automotive Window Film

As a window film dealer and installer it’s important to understand the visual quality guidelines associated with a film installation. These guidelines vary from automotive to residential applications and from solar control to safety and security films.

The International Window Film Association (IWFA)

The IWFA has created written guidelines to assist you in evaluating the quality of an automotive film installation. We outline the criteria that apply to installed automotive tint per the IWFA below. Please note that this criteria is only for the film and does not apply to any defect inherent in the glass itself. Installed automotive film on glass is not expected to have the same level of visual quality as glass.

Visual Quality Inspection Guidelines for Automotive Window Film

Installed automotive film normally has a slightly delayed time for full adhesion to be achieved since installation utilizes a surfactant or slip agent solution in water to float the film onto the glass: the excess water is then squeegeed out, but inevitably some residual water will remain between the film and glass.  

Adhesive Cure Time

This residual water will initially affect the visual clarity and full adhesion to the glass. The time to achieve full adhesion is often referred to as “the adhesive cure time,” but on automotive films it is really the “drying time” of the residual moisture.  Adhesion will be increasing from a lower value to the normal expected value during this time. The time it takes for the film to fully cure is related to thickness of the film and the various specialized coatings on the film.

Typical cure times may also be extended or shortened according to climatic conditions and vehicle storage. Certain automotive films with special high-performance coatings may have lengthened cure times. Consult the window film manufacturer for expected cure times of these films.

Inspection for visual quality can be made before full cure is attained. It should be noted that certain observations during clearing and drying, such as water distortion, and water haze are not to be regarded as defects.

Viewing Angles

The glass with applied film shall be viewed at right angles to the glass from inside the vehicle, and outside the vehicle from a distance of 3 feet. Viewing shall be carried out in natural daylight.

Evaluating the Installation

The auto installation shall be deemed acceptable if all of the following are unobtrusive: dirt particles, hair and fibers, adhesive gels, fingerprints, air bubbles, water haze, scores and scratches, film distortion, creases, edge lift, nicks and tears.

Inspection may be made within 1 day of installation. Obtrusiveness of blemishes shall be judged by looking through the film installation in natural daylight.

The top edge may have a maximum edge gap of 1/32 – 1/16 inch (1-2 mm). This ensures that film edges are not lifted up by contact with the frame gasket when a window is raised and lowered inside its frame.  In certain installations where top edge “shaving” has been performed, there may appear to be no gap at all.