Experiment: The Glass Temperature Test
What it demonstrates: The reflection-versus-absorption mechanics of Chapters 2.2–2.3 and 4.4 — read directly off the glass with a thermometer. This is the field test for the one property no spec sheet discloses: the mechanism.
Requirements: A vehicle with film on some glass and not others, or access to vehicles carrying different film types under identical conditions. An infrared thermometer. A full sun soak of 60–90 minutes.
Protocol:
- After the soak, measure the outer surface temperature of filmed and unfilmed glass at marked points.
- Measure the inner surface of the same panes.
- Record both readings per pane, plus all conditions.
The diagnostic logic. An absorptive film captures energy that bare glass would have transmitted — so the absorbing film runs hot, often hotter on its outer surface than bare glass beside it. A reflection-dominant construction turns energy away before it enters the system — so its glass runs cooler on both faces. The outer-surface temperature is therefore a field-measurable proxy for the film's absorption load, and the outer-versus-inner gradient sketches how much captured energy the system is holding.
Reading the results. Glass running distinctly hotter than its unfilmed neighbor indicates absorption doing the work; glass running comparable or cooler indicates reflection-dominant behavior. Per Series 2, the hot film is also re-radiating a share of its captured energy inward — the slow leak, now measurable from the driveway. One reading does not produce a laboratory mechanism breakdown, but a documented pattern across multiple soaks does something arguably better: it reveals which fate — closed door or slow leak — a specific film on a specific vehicle actually lives by.
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