Reduced thickness and gaps create localized heat-flow paths.
Visible fingerprint
cold spots aligned with wiring, pipes or framing.
What controls the reaction
Duration, temperature, moisture source, drying potential, material thickness and previous finishes all change the outcome.
What the surface cannot prove
A material response can reveal exposure without identifying the original source. Follow interfaces and adjacent layers before selecting a repair.
Verification
After correcting the source, record whether moisture, shape, odor or finish condition stabilizes over an appropriate period.