The wax seal stems from both tradition and necessity. Before corks were used, wax was one means of sealing wine bottles for storage and shipment. Even after corks became the standard, they were often unreliable. Wine would leak out and oxygen would sneak in, harming the wine, so wax was used to create a stronger, more airtight seal, particularly for bottles meant for longer aging.
Sealing wax allows a wine to hold for decades without the need to re-cork the wine. Wax seals also provide an additional guarantee of the wine's authenticity, as it would be difficult to falsify the contents of the bottle by opening and resealing it.
All of our premium vintage reserve bottles are waxed by hand, following traditional French bottling techniques.