Eli5: Why do all my cups and glasses have rims on the bottom that collect water in the dishwasher?

581 views

Eli5: Why do all my cups and glasses have rims on the bottom that collect water in the dishwasher?

In: Other

24 Answers

Anonymous 0 Comments

Depending on the material, it also makes the cup more rigid. A plane is easily bent/folded/distorted because every direction can be a fold line. A convex shape doesn’t fold easily, so the shape is sturdier.

Anonymous 0 Comments

A perfectly flat bottom is harder to make and a convex bottom would make for a wobbly glass or cup.

Anonymous 0 Comments

Without a rim they form an even flat surface that could slide more easily if condensation forms beneath it

Anonymous 0 Comments

It helps the cup sit flat on the table, if you made a cup with a perfectly flat bottom it would be much more difficult to get the symmetry right, and with mass produced cups that would almost always result in cups that can’t sit straight on a table and would fall over easily.

Edit: I got an award lol I’m not sure what it means but thanks a lot!

Anonymous 0 Comments

Your dishwasher should have a drying cycle where it heats up everything in the dishwasher, causing any residual water to evaporate off of the cups, plates, etc.

Also make sure to fill up the rinse aid compartment – this is used to alter the surface tension of the water, preventing stains and aiding in drying.

Anonymous 0 Comments

[removed]

Anonymous 0 Comments

Because if we tried to make them flat on the bottom they would always wobble, and they would slide around when there is even just a little moisture and, the clay ones would crack while being fired. But if they have a round rim or “foot” down there they fire nicely and are very stable and strong, and don’t wind up with more sloppy puddles on the bar counter.

Anonymous 0 Comments

Do you use a drying aid? It can help prevent standing water in a dishwasher. A lot folks never use it but most dishwashers benefit from it.

Anonymous 0 Comments

If it’s a ceramic cup, it needs a “foot” that does not have a coat of glaze so that it can be removed from the kiln after firing. If you look at any regular ceramic cup, the ring at the bottom of the cup, the “foot,” is unglazed and rough. If it had a coat of glaze, the glaze would melt and fuze to the kiln as it cooled. There are cups that have unglazed flat feet (not hard to make unlike people here suggest) but that unglazed, fired clay can absorb liquids (thus making it not dishwasher friendly), be rough to handle, and besides cups and bowls and other ceramic objects have had that traditional shape for millenia. Don’t know about glasses, but most glasses I own look like they have flat bottoms.

Anonymous 0 Comments

Because you have cups and glasses, which have rims on the bottom. So they collect water in the dishwasher.