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

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

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24 Answers

Anonymous 0 Comments

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Anonymous 0 Comments

Life pro tip. If the water in the rims is bothering you…once the dishwasher finishes all the wash cycles, open the door, drape a tea towel over the it, and reclose your door. The tea towel absorbs the water that is left in the rims.

Anonymous 0 Comments

It is perfectly possible to make a bottom which neither slides nor collects water- you just add 3 or 4 gaps in the rim

Anonymous 0 Comments

One easy explanation is production traditions, the molds used for making beaker are older than dishwasher.
No one thought about this Problem, even today a good amount of people still do t have a dishwasher, so not everyone get to knowtice this issue at all.
If you look at the McCafe cups in europe, you will see that McD had them made with an interrupted rim on the bottom so they still sit flush on a table but the water can easily rinse of.
The manufacturer normally just don’t care.

Anonymous 0 Comments

So you, like me, can forget it’s full and tip water over yourself and the floor when you unpack it.

Anonymous 0 Comments

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

Anonymous 0 Comments

Not an expert in any of those topics regarding cups, but Id speculate that for the case of pottery, its a product of the manufacturing process. In the production of pottery, a piece of clay is moulded wet, and then dried to set its shape. Due to the existence of gravity, the pottery will have to stand on something and dry that way. Then after drying, they fire the clay to make it water resistant. They will eventually have to scrape or get the dried clay off the thing it was sitting on while drying. If the bottom is flat, this would be problematic but if the surface in contact is a thin ring as opposed to a filled-in circle its easier to be released from the racks.

Plus, if its the same amount of material used, a dome is structurally stronger than a flat slab of material or feature of a design.

Anonymous 0 Comments

Also, most cups from IKEA have a little chip taken out of the rim, to make way for water in the dishwasher!

Anonymous 0 Comments

If it’s flat, there is a chance that if there is water at the bottom of it, the cup would slide.

Have you see before plastic cup with flat bottom? They slide when there are water at the base

Anonymous 0 Comments

The bottom rim helps cups not suction to surfaces under condensation and the air gap in the rim helps insulates your drink better. Some cups have gaps in the bottom rim to let water flow out, some don’t.