Define "natural".
The original formulas of lacquer and shellac were made from crushed beetle shells and distilled plant oils.
Sometime mixing two natural substances yields a product not found in nature. Are those two combined natural substances no longer natural? I always refer to something an old Druid witch told me once, "If the ancestors had superglue, epoxy, and spiderwire, they would have used it." If you're making an historically accurate reproduction, I understand choosing traditional methods. On the other hand, if functionality is your goal, use the most effective materials available.