What are the visual inspection standards for window film installation quality?

After a film is applied to flat glass, the overall light transmittance of the film plus glass will be lower than that of the original pure glass. All quality inspection standards should be based on the absence of defects in the glass itself.
Since solvents are used during installation, it will take a certain amount of time for the film to be fully attached after it is applied. Although some water cannot be seen, it still remains between the film and the glass. The complete adhesion of the film is also commonly referred to as the "film drying time". As the film dries, the viscosity of the glue will gradually increase. The speed of the film drying has a certain relationship with the thickness of the film and the metal content. Weather factors also have an impact on how quickly the film dries.
Before the film is completely dry, inspection of optical quality can be performed. It should be noted that some phenomena before the film is completely dry, such as blisters, image deformation of objects due to water, and water mist, are all normal phenomena.
The naked eye inspection of filmed glass should be from indoors to outdoors and from the correct angle, and the distance should be within 2 meters. The inspection should be conducted under normal natural light during the day and should not be directly exposed to the sun. The inspection area should be within 5 cm from the glass frame.
The installation will be considered qualified if there are no following conditions (except for normal phenomena that occur during the film drying process): debris, hair and fibers, glue agglomeration, fingerprints, bubbles, scratches and cracks in the film, and film body deformation , oil stains in the film, warped edges of the film, and knife marks. The above detection should be done within 24 hours after installation.
Since the presence of a frame will affect the perfection of cleaning and installation, if there is slight debris in the area, it is still qualified.
There is usually a width difference of 1 to 4 mm between the edge of the film and the edge of the glass. This is to facilitate the expulsion of water during installation. This also ensures that the film edge is not easily scraped up by the window frame. Scratching between the film edge and the window frame may cause the diaphragm to fall off.
For thick safety films, there is usually a width difference of 1 to 5 mm between the edge of the film and the edge of the glass. Multi-layer composite safety films also apply to this standard. It is recommended to reserve a width difference of 2 mm, especially for darker films, to reduce light transmission from the frame.
When the size of the window is larger than the normal size of the film, several pieces of film are allowed to be attached to a single piece of glass. It is normal to have seams between the films. Two adjacent membranes may not be directly connected, or may be overlapped, but no matter what form of connection is used, the width of the seam line shall not be greater than 1 mm.
Some specific membranes will take longer to dry. Please refer to the manufacturer's information for the specific membrane drying times of these varieties.