The temperature at which this happens is known as the "blocking temperature" and is specific to a particular material.
After one half-life has elapsed, one half of the atoms of the substance in question will have decayed.
The processes that form specific materials are often conveniently selective as to what elements they incorporate during their formation.
In the ideal case, the material will incorporate a parent nuclide and reject the daughter nuclide.
The procedures used to isolate and analyze the reaction products must be straightforward and reliable.
If a material that selectively rejects the daughter nuclide is heated, any daughter nuclides that have been accumulated over time will be lost through diffusion, setting the isotopic "clock" to zero.