Clean the surface of the plastic sheet, ensuring it is free of dust, oil, and other impurities. Take a section of protective film and gently place one end against the edge of the plastic sheet. Gently smooth the area of contact with your hand to observe whether the protective film adheres quickly to the sheet surface and whether it slips or becomes difficult to position during application. If the edge of the protective film remains stable when gently pushed, initial adhesion is generally satisfactory. If it easily peels off with a light touch, initial adhesion is insufficient.

After applying the protective film, apply even pressure to the surface with a clean, soft cloth to ensure a tight fit. Place the sheet in a suitable environment for daily use or storage. After a period of time, observe the condition of the protective film. Check for any warping at the edges, hollowing in the middle, or partial separation from the sheet. If the entire surface remains flat and tight, with no signs of separation, the adhesive is stable and suitable for long-term use.

After the protective film has been applied for a while, select a spot along the edge of the sheet. Grab a corner of the film and peel it off the plastic sheet with slow, even pressure. During the peeling process, feel for the appropriate amount of pressure, ensuring it's neither too weak or too difficult to remove, potentially causing the film to break. After peeling, carefully inspect the surface of the plastic sheet. If the surface is clean and free of adhesive residue, the adhesion is adequate. If there are noticeable adhesive residue, the adhesion is not up to standard.

Simulate different possible environments a plastic sheet might encounter. For example, place the sheet with the protective film applied in a slightly warmer environment for a period of time. Check to see if the film softens or separates from the sheet. Then, transfer the sheet to a slightly humid environment and observe if moisture reduces the film's adhesion or causes mold. If the film maintains a good adhesion after testing in different environments, it demonstrates stable adhesion and meets your requirements.