Bowl proportions.

[Bobg]

I make quite a few large mixing bowls, it the main product I sell. I've been making the base 6 inches, height is 6 inches and top diameter is 10 inches. Some times the base looks to small to me, but all my customers say they look alright and they must since I sell quite a few of them. But, I was wondering if there's a rule of thumb for the diameter of the top, base and height.

[clay lover]

I make quite a few large mixing bowls, it the main product I sell. I've been making the base 6 inches, height is 6 inches and top diameter is 10 inches. Some times the base looks to small to me, but all my customers say they look alright and they must since I sell quite a few of them. But, I was wondering if there's a rule of thumb for the diameter of the top, base and height.

 

 

Seems like the curvature of the inside would have some determining factor. Foot would not be larger that the turn from curved base to curved wall?

[OffCenter]

I make quite a few large mixing bowls, it the main product I sell. I've been making the base 6 inches, height is 6 inches and top diameter is 10 inches. Some times the base looks to small to me, but all my customers say they look alright and they must since I sell quite a few of them. But, I was wondering if there's a rule of thumb for the diameter of the top, base and height.

 

 

Ignore the rules and what customers tell you and trust yourself. It doesn't hurt to check out what other potters consider a good bowl (online galleries, 500 Bowls book, etc.) and sometimes you may need to get away from your bowls for a while to see them with "fresh eyes", but don't look for rules.

 

Jim

[Pompots]

I agree with Offcenter's comment, also the rules where made to be broken. As long as you like your shapes and they are selling there is nothing wrong with it. Keep it simple!

[Pres]

I make quite a few large mixing bowls, it the main product I sell. I've been making the base 6 inches, height is 6 inches and top diameter is 10 inches. Some times the base looks to small to me, but all my customers say they look alright and they must since I sell quite a few of them. But, I was wondering if there's a rule of thumb for the diameter of the top, base and height.

 

 

Ignore the rules and what customers tell you and trust yourself. It doesn't hurt to check out what other potters consider a good bowl (online galleries, 500 Bowls book, etc.) and sometimes you may need to get away from your bowls for a while to see them with "fresh eyes", but don't look for rules.

 

Jim

 

 

Proportions aside, the only rule I follow on a bowl is that the inside curve from the bottom to the top not break or get flat spots. This should be especially true for a bowl made for mixing or batter. I do like to make the rim intrude on the opening in a batter bowl to emphasize the spout and to control the batter inside the bowl.

[Stuart Altmann]

Of course, a mixing bowl could be tipped over just from the force of mixing, particularly if the bowl's content are fairly rigid. But you probably want to know when it will tip over spontaneously. An empty bowl or any other object sitting on a horizontal plane surface, like a table top, will fall over spontaneously whenever the vertical projection of its center of mass falls outside its base, i.e. outside its horizontal foot ring in the case of a bowl. This is the basic rule.

 

 

For a mixing bowl, this scenario is complicated by two aspects of its contents at any given time. First, the material being mixed affects where the center of mass is. If the center of mass of the bowl's contents is lower than that of the empty bowl and the contents are sufficiently 'stiff' --like, say, mashed potatoes--so that they do not shift position appreciably when the bowl is tipped, then the contents lower the center of mass of the bowl+contents, so unless the stiff ingredients are piled up so much off-center that the vertical projection of the combined center of mass falls outside the foot ring, the bowl will not spontaneously tip. Conversely, if the contents are sufficiently fluid, they may flow around the mixing spoon rapidly enough that the shifted positions of the center of mass of the bowl-plus-contents never gets out beyond (vertically projected) the base.

 

Thus, a potter can easily influence a bowl's "tipability" in two ways. First, keep the center of mass low. For example, have a wall that is thicker in its lower parts (walls and base )and that does not flare outward very much, relative to its height. Second, make the base both wide and thick/heavy.

 

One other factor is sheer mass and density. When my sister wanted flower vases that would not easily tip over when she put her very tall orchids in them, I loaded my standard clay with silica, which is about the densest of the common materials in my clay and I used it to make vases with walls that, while straight inside and out, are thickest where they meet the thick, wide base. The vases are narrowest at the top, giving the flower stalks minimal leverage against the vases' walls.

[CarlCravens]

I don't expect a mixing bowl to stay upright on it's own... my assumption is that I'll need to hold onto it. I also expect to be able to easily tip the bowl while mixing batter, having it rest on it's lower curve. (Easier on the wrist when whisking.)

 

For reference, my Pyrex (gasp!) mixing bowls have a 7.5" inside diameter with a 0.5" lip, and a 3.5" foot. That's not quite a 2:1 (2 to 1) ratio, lip to foot. I like the got size here, and the belly has a good curve, but the inside bottom is flattened, I presume to keep the glass a uniform thickness. (Though I don't know if that's for cost, weight and/or thermal reasons.) I agree with the earlier comment, a smooth curve is preferable here.)