Patent ID: 8501481

Claim:
A tracing method, comprising: (a) providing a tracer comprising a liquid perfluorinated tracer having at least one of (i) a —CF 2 —CF 2 — portion, or (ii) spectral characteristics corresponding to highly electronegative fluorine substituents of an organic composition, encapsulated within at least one permeable wall capsule having a first composition within a polymer matrix having a second composition, the polymer matrix having a controlled matrix permeability for the perfluorinated tracer, wherein the polymer matrix substantially causes a steady state release rate of the perfluorinated tracer into air for an extended period; (b) physically blocking a release of the perfluorinated tracer with a barrier substantially impermeable to the perfluorinated tracer; (c) altering the barrier to permit contact of the polymer matrix with air, to thereby permit a release of the perfluorinated tracer into the air, wherein prior to changing the barrier, the release of perfluorinated tracer is undetectable and after changing the barrier the release of perfluorinated tracer is detectable.