Acid-free tissue: Very thin wood-free or rag content papers used as wrappings for articles likely to tarnish or suffer from any free chemicals or impurities in the wrapping. Specific pH values are important.

• 无酸薄纱纸:很薄的化学浆或含有布质的纸张。用以包裹那些容易被化学品或杂质染污或变黄的货品。这些必需有一个固定的酸碱值。