Paper that is not acid free breaks down over time and outside influences can cause irreversible damage. While preservation cannot alter harm already caused by time, its main purpose is to make sure that no more injury happens to artifacts in the future.
Some of the most harmful materials to paper collections are everyday items that seem so innocent.
Here are a few examples of archival enemies:
Scotch Tape- while it keeps paper together, it also causes acidic damage usually presenting itself as dark yellow stains.
Metal Paperclips- over time metal rusts and can harden making it difficult to remove. This usually leads to tears and stains.
Foxing- this is when dark red/orange stains appear on documents. Often it is caused by damp environments, exposure to metals or even the very material the paper is made of.
While this damage cannot be reversed, it is important to keep documents you wish to preserve for the future away from scotch tape, metal paperclips and at regulated temperatures.