Table 7 Review of previously reported cleaning and reparation methods for PLMs

Cleaning

Adhering to the principles of minimal intervention and safety to minimize the impact of chemical agents on the palm leaves.

^7,47

Gentle cleaning is suitable for removing surface dirt from palm leaves without causing damage to the original material.

⁴⁷

For areas with painted decorations and inscriptions, ethanol-soaked cleaning is recommended to avoid damage to the text caused by wiping.

⁷

For heavily contaminated areas, trichloroethane can be used for cleaning, but its use should be limited to avoid over-application.

³²

Distilled water is suitable for cleaning palm leaves with water-soluble inks, but further research is needed to understand the long-term effects of these solvents on the palm leaves. The cleaning process should be carried out carefully to prevent over-cleaning, which can damage the palm leaves.

^12,25

Filling repairing

Handmade Paper

Japanese Paper

Layered processing can be applied according to the thickness of the palm leaves, making it suitable for repairing both small and large areas of damage. During the repair process, these papers are often used in combination with adhesives such as PVAC emulsion, PVA, EVA, methylcellulose, and wheat starch. The repair paper can also be dyed to achieve better aesthetic results.

^{7,15,16,28,29}

Thai Mulberry Bark Paper

Paper Pulp

For severely damaged palm leaves, a pulp repair machine combined with colored pulp can be used for restoration, while minor damage can be addressed using manual pulp filling methods.

^23,44

Palm Leaf

Palm Leaf

Repair can be carried out using overlap (2 mm) or inlay methods, in combination with adhesives such as EVA, PVAC, PVA, and wood glue.

^{7,12,17,26,48}

Bark Materials

Birch Bark

Bark materials, such as birch bark or the inner bark of mulberry trees, can be used and cut to match the shape of the damaged area. During the repair process, two layers of bark can be stacked with a layer of Japanese Kozo-shi paper in between, or covered with Japanese mitsumata paper, and fixed using adhesives such as acrylic emulsion, wheat starch, and PVA.

^{27,28,29,32,48}

Mulberry Bark