Hanji paper (freshly prepared Hanji H)

Ingredients

bast fibers of paper mulberry (Broussonetia kazinoki), potash (K2CO3) solution obtained from ashes of a stem of barley, mucilaginous material from the root of Hibiscus Manihot L., groundwater

Preparation Steps

Original Recipe Text

The manufacturing follows a Korean traditional leaching and sheet-forming process. Step 1: Potash (K2CO3) solution is obtained by leaching 3.8 kg of incompletely burned barley ash in 25 L of groundwater at 60 °C. Step 2: One-year-old bast fibers of paper mulberry (B. kazinoki) are swollen in water for 2 hours. Step 3: 1.8 kg of these fibers are boiled in 25 L of the potash extract in a caldron at 104 °C for 2.5 hours. Step 4: The resulting pulp is washed overnight with streaming groundwater. Step 5: The pulp is manually pounded for 4 hours using a wooden club. Step 6: Mucilaginous material extracted from the root of Hibiscus Manihot L. (after swelling in cold water, squashing, and filtering) is added to the pulp suspended in a vat to control drainage and ensure fiber dispersion. Step 7: Sheets are formed using a traditional Korean mold and dried on a hot plate below 80 °C for 10 minutes (p. 4623).

Evidence

"Korean Hanji paper is traditionally made from bast fibers of one-year-old paper mulberry trees (Broussonetia kazinoki Siebold) and is ranked as one of the strongest papers available worldwide."

Remarks

The paper identifies Hanji as having the highest molecular weight ever reported for paper (>1,400 kDa) (p. 4621). Traditional cooking chemicals like buckwheat or barley ash are found to be significantly less aggressive than modern sodium hydroxide, preserving the high degree of polymerization (DP) and preventing severe degradation (p. 4625). The study estimates the life expectancy of Hanji to be approximately 4,000 years under natural aging conditions, provided there is no UV exposure (p. 4621).