Some cups, etc are easy to pour from, even without lip designed for pouring. While other cups make a mess. Is it just the thickness of the the lip? I feel like coffee cups are particularly bad.
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It’s to do with the shape of the lip. Some shapes are better at directing the liquid down the outside of the object and some are better at separating the liquid from the object. You see this with items designed to pour as well.
I just want to say, if your *bowels* pour easily you should see a doctor!
As for your question, yes it’s at least partly the thickness of the lip, but also the shape of the lip too. If the lip flares outwards a little bit, that creates a much sharper angle between the stream and the cup wall at the point where gravity is trying to pull the liquid away from contact with the lip.
[deleted]
It’s to do with the shape of the lip. Some shapes are better at directing the liquid down the outside of the object and some are better at separating the liquid from the object. You see this with items designed to pour as well.
I just want to say, if your *bowels* pour easily you should see a doctor!
As for your question, yes it’s at least partly the thickness of the lip, but also the shape of the lip too. If the lip flares outwards a little bit, that creates a much sharper angle between the stream and the cup wall at the point where gravity is trying to pull the liquid away from contact with the lip.
Water, because it’s pulled down by gravity, will always want to find the lowest point it can reach without being stopped, but it also really likes to slightly stick to other materials. Which we call adhesion.
So if you have a drinking mug with a round lip, the water will want to go down, but it will also cling to the side of the mug as it does so, cause it’s still going down like that.
But if you have a container with a pouring lip, the water can’t do that, because in order to cling to the side of the container, it will have to travel up again past the underside of the pouring lip. And because the water is pulled down by gravity, it can’t go up, so it has no choice but to fall straight down.
Think of a sagging clothes line that’s collecting dewdrops. From the side the droplets will travel to the middle, because they’ll go down that way, but once at the middle they would have to go up again so they have no choice but to fall off the clothes line.
Water, because it’s pulled down by gravity, will always want to find the lowest point it can reach without being stopped, but it also really likes to slightly stick to other materials. Which we call adhesion.
So if you have a drinking mug with a round lip, the water will want to go down, but it will also cling to the side of the mug as it does so, cause it’s still going down like that.
But if you have a container with a pouring lip, the water can’t do that, because in order to cling to the side of the container, it will have to travel up again past the underside of the pouring lip. And because the water is pulled down by gravity, it can’t go up, so it has no choice but to fall straight down.
Think of a sagging clothes line that’s collecting dewdrops. From the side the droplets will travel to the middle, because they’ll go down that way, but once at the middle they would have to go up again so they have no choice but to fall off the clothes line.
Water (and liquids made from it) like to stick to things, but that stickyness has its limit. Some vessels, by having a kinda “pointy” pouring lip, take advantage of this, because the water follows the curve but the lip stops abruptly, “freeing” the water because it cannot go around and up the lip as it would need more stickyness than it has.
With other containers, you can limit how much water it sticks to the outside by not pouring it slowly, taking advantage of another trait of water: it likes to stick to itself. As long as you’re decisive and you’re not trying to “pour a drop”, you should be fine.
Water (and liquids made from it) like to stick to things, but that stickyness has its limit. Some vessels, by having a kinda “pointy” pouring lip, take advantage of this, because the water follows the curve but the lip stops abruptly, “freeing” the water because it cannot go around and up the lip as it would need more stickyness than it has.
With other containers, you can limit how much water it sticks to the outside by not pouring it slowly, taking advantage of another trait of water: it likes to stick to itself. As long as you’re decisive and you’re not trying to “pour a drop”, you should be fine.
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