Chen Liji sealed pills in beeswax to beat humidity

Chen Liji was founded in Guangzhou in 1600 by Li Shengzuo and Chen Tiyuan, and became one of the longest-continuously-operating pharmaceutical makers in China.

The pharmacy also worked with imported and highly volatile ingredients — including resins and balsams sourced from as far as the Mediterranean — that were especially vulnerable to oxidation and moisture once compounded into a pill. The standard response available at the time was tighter storage: drier warehouses, more frequent inventory turnover, smaller batches made closer to the point of sale — mitigations that reduced spoilage without eliminating it, and did nothing for the pills a customer carried home into their own humid household.

Sealed each pill in an airtight beeswax shell, making the pill itself impervious to any environment, so preservation traveled with it instead of depending on storage.

Beeswax formed a continuous airtight seal, blocking moisture and oxygen.

The shell traveled with the pill, so protection didn't depend on storage conditions.

Edible wax added no risk to the medicine, making it safe to swallow.

Unit-level sealing eliminated spoilage entirely, not just slowed it.

When the environment can't be controlled, make the product itself impervious with a cheap, inert, unit-level barrier.

Wax-sealed Chen Liji pills reportedly remained usable for decades under normal storage, and the method proved its durability dramatically during the Second Sino-Japanese War, when wax-shell pills recovered from wells after years of submersion were found undamaged. The technique spread from Chen Liji to pharmacies in Beijing and Hangzhou, and in 1981 UNESCO commissioned a documentary record of the wax-pill production process.