The treatment of microbubble disease of 20th century cellulose acetate microfilm: application of ethyl cellulose and microrepair method

Microbubble disease observed in cellulose acetate microfilm is accompanied by the production of vinegar syndrome, which affects the image integrity. In the present study, samples of cellulose acetate microfilm with microbubble disease were selected to investigate potential treatment methods. Samples were sourced from the Republic of China (AD 1912–1949) microfilm collections held in the Second Historical Archives of China. A combination of optical microscopy and a stainless-steel needle was used to remove plasticizer exudation within microbubbles. The plasticizer was effectively removed by infiltrating butan-1-ol into the microbubble from a small hole made by the stainless-steel needle. SEM and confocal microscopy were used to study the morphology and roughness of the internal surface of the microbubbles. It was found that the blurry image could be attributed to light scattering from the rough surface. Ethyl cellulose was used to fill the interior of the microbubble to obtain a clearer image. To determine the protective potential of this filling material, the chemical and mechanical properties of coated film after dry heat, hygrothermal and UV accelerated ageing were measured. Based on the above-mentioned results, it is encouraging that a new microrepair method and its corresponding method are offered in film treatment work.