Digitize first: use a high‑resolution flatbed scanner or a book‑style scanner with at least 300 dpi, keep the paper flat, use a neutral background, and calibrate white balance to preserve ink tone. Scan in lossless TIFF, then create a compressed PDF for everyday access. Store the original in a climate‑controlled environment—low humidity, 20–22 °C, no direct light, acid‑free sleeves or sleeves with UV protection. Label each diary with a durable tag and keep a digital log of the physical location. That way the ink stays intact, and you have a backup that’s searchable and portable.