Callie Beller Diesel Posted July 30, 2020 Report Share Posted July 30, 2020 I have a commission for a larger bowl than I usually make. Just to save time, can people who make a bowl that’s about 16” finished diameter tell me how much clay you start with? The overall form needs to be a bread bowl style: rounder aspect as opposed to a more upright style, but not too shallow either. Link to comment Share on other sites More sharing options...
liambesaw Posted July 30, 2020 Report Share Posted July 30, 2020 I've done a few, i usually go 12 pounds and keep the base thick for stability and then trim it off after Link to comment Share on other sites More sharing options...
CactusPots Posted July 31, 2020 Report Share Posted July 31, 2020 That's a really difficult skill, judging how much clay to make a specific size and shape that's not a frequently repeated product. I can somewhat do it after 25 years. I don't think it's anything that can be taught or even calculated. Human brain is really marvelous. Link to comment Share on other sites More sharing options...
Hulk Posted July 31, 2020 Report Share Posted July 31, 2020 Takes a lot of material to get bigger in three d Link to comment Share on other sites More sharing options...
neilestrick Posted July 31, 2020 Report Share Posted July 31, 2020 I make sinks that are 16" in diameter, but I leave them thicker than a regular bowl, and I do them in porcelain which has a higher shrinkage rate, but I use 18 pounds for those. So Liam's 12 pounds is probably a good starting point. Or go with 14 pounds and cut off the rim if it gets too big. Link to comment Share on other sites More sharing options...
Mark C. Posted July 31, 2020 Report Share Posted July 31, 2020 I throw in porcelain which does not throw as well as stoneware. 14-18# is a good start-maybe 16# and trim it down. Extra is easy to trim off but not enough is not going to work. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted July 31, 2020 Author Report Share Posted July 31, 2020 Thanks All! I use a stoneware that behaves a lot like a porcelain in that it's got a very fine tooth, it's very pyroplastic and it shrinks a fair bit when it's wet. I just need a ballpark for a starting point. I'll keep everyone posted. Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted July 31, 2020 Report Share Posted July 31, 2020 On 7/30/2020 at 4:45 PM, Callie Beller Diesel said: I have a commission for a larger bowl than I usually make. Just to save time, can people who make a bowl that’s about 16” finished diameter tell me how much clay you start with? The overall form needs to be a bread bowl style: rounder aspect as opposed to a more upright style, but not too shallow either. Callie, This worked for me when I was required to make large punch bowls. early on, I quit using weight of clay for estimating clay requirements, and switched to volume. Easy to estimate and to measure. Set my units to be cm or 10's of cm. Sketched the profile of the bowl showing the outside and inside surfaces in a cross section assuming that the bowl was half of a sphere. wrote down the dimensions of the diameters and wall thickness targeted. Assumed that the shrinkage was about 15% wet to final. so the dimensions were 15% more than my target dimension. got out my geometry formula tables and my slide rule and made some volume estimates of the cc's of clay needed. added some volume to allow for the foot ring. rounded that up numbers to even 10CC and took the cube root of that volume to be the size of a cube of wet clay. LT Link to comment Share on other sites More sharing options...
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