In 1953 this test was used to easily identify that the 'Piltdown Man' was forged, almost 50 years after it was originally 'unearthed'....provided that all the other natural variables remain constant.Only in 1886 did French chemist Henri Moissan isolate elemental fluorine using low-temperature electrolysis, a process still employed for modern production. "Solid State Molecular Structures of Transition Metal Hexafluorides".
The fluctuating amount of fluoride found in groundwater means the objects in comparison must be in the same local area in order for the comparisons to be accurate.
As not all objects absorb fluorine at the same rate, this also undermines the accuracy of such a dating technique.
Items such as bone that are in the soil will absorb fluoride from the groundwater over time.
From the amount of absorbed fluoride in the item, the time that the item has been in the soil can be estimated.
Although this can be compensated for by accommodating for the rate of absorption in calculations, such an accommodation tends to have a rather large margin of error.