Synthetic chemistry in Ancient Egypt

About 20 years ago, Walter et al (Nature, 1999) reported evidence that Ancient Egyptians were manufacturing synthetic products for cosmetic use (make up).
Using crystallography and chemical analysis techniques to study the composition of samples of cosmetic powder dating from between 2000 and 1200BC, the authors found natural compounds - namely crushed ore of galena (PbS) and cerussite (PbCO3), but not only. They identified the presence of laurionite (PbOHCl) and phosgenite (Pb2Cl2CO3), that cannot be found in nature and do not result from natural chemical modification. These substances were therefore produced artificially.

Beck et al (Nature Communications Chemistry, 2018), replicated these observations.

The dating found by radiocarbon is nevertheless not straightforward to interpret. The authors used samples coming from the Louvres Museum, and attributed to different periods - see table below, second column, the basis of this attribution is not reported.
They nevertheless found values that did not fit “their expectations” - fifth column in the table- some of the samples turned out to be much older than they expected. They considered several factors to recalibrate and interpret what they deem to be the most likely age of the sample (about 1500 BC).

The paper is Open access (free) if you want to understand how they came to their conclusions and see if their interpretation sounds correct.