Why on earth do all coffee mugs come equipped with that little (and sometimes not so little) puddle receptacle on the bottom? What purpose does it sever other than to collect enough water to make a mess on the floor every time I empty the dishwasher?
This is a part rhetorical, part serious questions, I mean really, what is that indent for?
Is this an artifact of manufacturing? If this sits on a flat surface with a flat bottom, isn’t it going to be harder to get off the kiln/mold ?
Just a thought.
That’s a good point. Makes me wonder how many other manufacturing artifacts we experience every day that we just live with, work around, or have become desensitized to?
The indent creates a tiny pocket of air that cushions the cup just a little as you put it down to keep the material from chipping. It’s called the “denteler” and was invented by Alexis Menatti in France in 1894.
I knew someone had to have the answer! Cheers.
But would that actually work? I don’t see how there would be any "cushion of air" since the cup never gets compressed. There’s a pocket of air trapped under there once the cup is set down, but it wouldn’t be compressed, so wouldn’t act as a cushion.
But I could see other advantages to a concave cup bottom. I wonder if cup bottoms are concave because that way you can be absolutely sure that they’re not even a tiny bit convex, which could cause them to wobble. It also possibly makes them sit better on a irregular surface.
There’s a perfectly good reason for it that has nothing to do with air cushons (although that may be true too). Notice how, on most mugs, the ring around the bottom of the cup isn’t shiny but the bubble area is? That’s because the glaze (which is essentially glass) isn’t usually applied to the edge that will be touching because a) you don’t want to deal with molten glass hardening into the surface of whatever it’s sitting on and b) it wouldn’t be shiny even if it didn’t stick to it because it’s touching something with it’s own texture. The depression isn’t touching anything during the firing so the glaze is allowed to become all smooth. On a related note white ceramic mugs are frequently (always?) made from porcelan which is very smooth even without a glaze.
Another advantage that comes with the indent is the fact that it avoids direct contact with the surface you place it, that way your coffee takes longer to cool (you can see that on cardboard coffee cups also)
this is what Ikea has done regarding the issue:
http://www.gizmodo.com/gadgets/gadgets/ikea-trofe-mug-dishwasherowned-199374.php
you see a little drain cleft in the bottom edge, they appear very proud of it.