NOTICE: This is a simple manual for treating library materials in general based on cases in the National Diet Library. When you treat rare books or severely damaged materials, we recommend you to consult an expert in conservation treatment. Cleaning mold-damaged materials Stroking off moldy substance attaching to materials using disinfectant ethanol, and removing dirt with a vacuum cleaner or a brush. 1. Before starting 1-1. Ensuring the safety of human body To avoid molds intake and adhesion, wear a mask (a commercially available dust mask), gloves (disposable thin plastic gloves), a lab coat, shoe covers, etc. Molds can cause allergy and other health hazards to people; people in poor health should not engage in this work. 1-2. Isolating materials and preparing a workspace Mold-affected materials must be isolated from other materials and stacks to prevent contamination spreading. Cleaning work must be done away from other materials and people, with good air circulation. Ethanol volatility requires extreme care on air circulation for indoor work. If possible, use a cleaning aspirator HEPA (High-Efficiency Particulate Air) filter: filter or vacuum cleaner with HEPA filter, with mesh fine enough to trap mold spores and/or an air purifier. Outdoor work in good weather is also recommended. 2. Stroking off moldy substance Clean mold-affected parts with a paper towel soaked with ethanol of 70-80%. Give one-way strokes to avoid spreading dirt; do not rub. Always use clean side of a paper towel, with the dirty side folded inwards. Note: Make sure to test an out-of-the-way corner to check if ethanol discolors the cover or ink. 3. Cleaning materials With a HEPA filter vacuum cleaner: Cover the suction mouth with a coarse cloth or attach a special brush, and vacuum up remaining surface dirt. A vacuum cleaner with air volume control is preferable. With a brush: Brush away dirt if a vacuum cleaner is unavailable. Hold materials firmly to prevent dirt from getting inside and brush downwind in the direction of aspirator. Do this on the three edges. 4. Cleaning stacks Wipe off bookshelves with a tightly squeezed wet rag, and then with an ethanol-wet paper towel in good ventilation. Do not forget to clean floors around shelves, as well. 5. After cleaning work Take off the mask and gloves gently, folding external side inward to avoid molds scattering. Dispose of them in a sealed garbage bag. Wash the brush/brush for vacuum cleaner with neutral detergent and rinse them well. Soak the entire hairy part in disinfectant ethanol for 30 minutes. Drain it off and dry well. 6. Preventing a mold outbreak and recurrence Environment control is crucial to prevent a mold outbreak and recurrence. A mold outbreak is inhibited when the relative humidity around materials is under 60%; it is recommendable to install air dehumidifiers to avoid hot and humid condition, or to provide good air circulation by running fans. Cleaning frequently to remove dust and dirt, which molds live on; taking shoes off and wearing footwear for exclusive use in stacks so as not to take dirt in; checking materials regularly for early detection is also helpful in avoiding a mold outbreak.