It's not you, coffee mug, it's us.
Turns out, the reason us silly humans have been spilling coffee all over ourselves isn't because of a design flaw, but because we're not holding our mugs correctly, according to recent research.
A new study in the Achievements in the Life Sciences journal claims to have found the most efficient way to hold a mug without getting our favourite brew all over our clothes, thus ruining our day and killing our buzz.
Entitled "A Study on the Coffee Spilling Phenomena in the Low Impulse Regime," author Jiwon Han looked at how the movement of fluids are affected by how we hold mugs. The goal of the study was to find out why coffee in a mug has the tendency to "splash aggressively against the cup and ultimately spill," while wine in a wine glass moves like "calm waves... gently [rippling] on the surface."
Han begins his introduction to the study thusly:
"Rarely do we manage to carry coffee around without spilling it once (Fig. 1). In fact, due to the very commonness of the phenomenon, we tend to dismiss questioning it beyond simply exclaiming: 'Jenkins! You have too much coffee in your cup!'"
Using detailed formulas and graphs, Han figures out that the coffee spilling problem is actually rather simple to solve: it's all in the way you hold the mug.
Rather than wrapping your fingers around the handle and/or the mug itself, you (and Jenkins) should be holding your mug wrist bent at an angle, with your fingers holding the rim of the mug — what Han calls the "claw-hand model" — like this:
Han discovered this method measuring the frequency of oscillations in mugs, where he detected a significant difference in spillage using the handle and the claw-hand method.
"Since the magnitude of acceleration in the claw-hand model is significantly smaller, the claw-hand posture is less likely to spill coffee," Han wrote, adding that walking backwards may also lessen the chances of spilling coffee. "Since we are not accustomed to backwards walking, our motion in the walking direction becomes irregular, and our body starts to heavily rely on sideways swinging motion in order to keep balance."
However, he also notes that walking backwards isn't all that practical, either. "Walking backwards may be less of a practical method to prevent coffee spilling than a mere physical speculation. A few trials will soon reveal that walking backwards, much more than suppressing resonance, drastically increases the chances of tripping on a stone or crashing into a passing by colleague who may also be walking backwards (this would most definitely lead to spillage)."
He concludes that the claw-hand posture will "have similar effects on the coffee oscillation as walking backwards," meaning less spillage.
So there you have it, folks: either you can start walking backwards and potentially hurt yourself (or others) in the process, or you can take a gander at shaping your hand into a claw while you hold your coffee mug. Either way, at least you'll keep your coffee where you want it and not on your shirt.