Commonly termed French polish by the layman shellac has been used for countless years. Lac is from the sanskrit word lakh meaning 100,000 which refers to the insect larvae that swarm the lac trees in brood season. The natural resin secreted on to the trees by the lac insect is collected to produce shellac. There are a number of by products of this resin and it is known ancient asian civilisations used the dye taken from lac for dyeing silk and leather.
It is now also used in products for veterinary and modern medicine. It was in the 18th century that the resin started to be used for waxing and polishing furniture. It wasn't until around the 1850s that shellac was commonly used as a clear finish. There are a variety of shellacs the most commonly used being orange and clear shellac.
Shellac is processed from Seedlac. Seedlac produces a higher grade polish that I use on particular items at my discretion or if the customer requests me to do so. A superior finish in many ways Seedlac highlights the grain better and creates what I think is a better patina.
Another product I use is Button Lac. Not commonly used by furniture restorers as it is not easily manufactured. I personally prefer to use this Shellac on table tops because of its greater durability than the commonly used Shellacs.