The core of inspecting the protective film is “full coverage + no damage + no peeling,” which can be done through visual inspection and simple tests.
1. Visual inspection
Overall observation: ensure the film fully covers the steel surface with no missed edges or unadhered areas, paying attention to corners and cut edges.
Damage check: look for scratches, punctures, or tears, especially in areas prone to stress during transport or stacking; no significant damage is acceptable.
Contamination check: the film surface should be free of oil, rust, or cement dust. If present, wipe and verify no penetration under the film.

2. Adhesion and peeling test
Edge adhesion: press the film edges by hand; no lifting or air pockets, hand swipe should feel secure.
Random spot check: gently pull the film at least 3 spots on the plate; no easy peeling or delamination, moderate adhesion is ideal.
Bubble check: no large-area bubbles; small isolated bubbles (diameter <5mm) are acceptable; dense or large bubbles are unacceptable.

3. Special scenario checks
After humid/outdoor storage: check for whitening, softening, or overly tight adhesion; replace if issues arise.
After transport: check areas contacting straps or lifting devices for pressure marks or damage; edges and corners should be intact.

4. Simple functional tests
Peel test: remove a small corner piece and check the steel surface underneath; no adhesive residue or gloss change confirms non-corrosiveness.
Water test (if needed): spray a small amount of water on the film; no water penetrates under the film, confirming effective waterproofing.