If there’s one thing you know about museums, it’s that their guards spend a lot of time making sure visitors don’t touch the objects. But why can’t we touch things?
Well, your fingers likely have a pH value of between 4.5 and 5.75, making them about as acidic as tomato juice or black coffee. These acids can etch an image of your fingerprints into metal or change the chemistry of varnish on a painting. Even when your hands look clean, they're often not. All that dirt can easily transfer to a work of art, dulling and damaging it over time. Paper is even more delicate and absorbent of acid, grease, and dirt than paintings on canvas or sculpture, which is why works of art on paper are often framed under glass to protect them. But even marble, stone or metal sculptures can be damaged over time by repeated touches, which wear away the finish.
Why does any of this matter? Part of the job of amuseum, is to preserve art for the future, not in a vault where no one can see it, but for YOU to look at, enjoy and learn from. So do your best to touch with your eyes rather than your hands when you’re visiting.