Why? Basically, these metal baddies like to rust. If you live in a humid environment or near the ocean, they’ll rust much quicker. The rustier the fasteners get, the more they stick to and eat through paper.
Office Depot -- we swear we don’t own any stock -- sells 200 jumbo vinyl coated paper clips for $5.49, so they are incredibly affordable.
The moral of this post is to be kind to your paper and avoid metal fasteners, not to mention that as we’ve noted previously, rust sucks! Join us in our never-ending quest to keep oxidation as far from important documents as humanly possible! (Or, barring that, at least show your archives spirit by wearing a pertinent hoodie.)