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Series 5 · Chapter 5.7

Experiment: The UV Fade Test

What it demonstrates: The UV story of Chapters 1.3–1.4 and the adhesive-layer protection of Chapter 4.1 — over weeks rather than minutes, with the most visually persuasive result in this series.

Requirements: Three identical material samples — fabric swatches, colored paper, or plastic. A sunny window with filmed glass, a sunny window with unfilmed glass (or open exposure behind clear glass), and a drawer. A camera. Patience: weeks to a full season.

Protocol:

  1. Place one sample behind the filmed glass and one behind the unfilmed glass, in equivalent sun exposure.
  2. Place the third sample in darkness — the control that isolates light exposure as the variable.
  3. Photograph all three at fixed intervals — weekly is ideal — under consistent lighting, labeled and dated.
  4. Continue for at least eight weeks; a full season is better.

Why a control matters. If the dark-stored sample stays unchanged while the exposed samples diverge, the cause is isolated to exposure — basic experimental design, and the difference between a demonstration and an anecdote.

Reading the results. UV-A damage is cumulative and invisible day to day; the photographic series is what makes it visible. Over a season, the unfilmed sample fades and degrades while the filmed sample tracks the dark control far more closely. Per Series 1, UV-A is the band that survives the atmosphere and drives material degradation; per Chapter 4.1, quality film's UV absorbers in the adhesive intercept it. This is also the experiment for skeptics unmoved by thermal arguments — heat debates invite quibbles about conditions, but a side-by-side photograph of one faded swatch and one preserved one, with a dark control validating both, closes its own case.

If you're just finding this page, here's the quick context: our focus is sharing the science behind the sun's energy and how window film actually affects it. This is one chapter in an ongoing series — to see more, visit our page or give us a follow to keep window film and sun's energy facts coming to your feed.