An intentionally untreated or differently treated comparison area used to interpret the effect of a test or restoration process.
GlassRenu · Educational illustration
Meaning and boundaries
A control must be comparable in glass, damage, exposure, and viewing conditions; an unrelated lite is not a valid control.
Why it matters in glass restoration
Side-by-side comparison helps separate treatment effects from lighting, photography, pre-existing distortion, and natural variation.
Related terms
References
- U.S. General Services Administration — Cleaning Historic Masonry
Publisher’s original source - National Institute of Standards and Technology — NIST TN 1297: Guidelines for Evaluating and Expressing Measurement Uncertainty
Publisher’s original source - Getty Conservation Institute — Twentieth-Century Building Materials: History and Conservation
Publisher’s original source