Best insulated ceramic cup material?

[hyakuraiju]

What is some of the best ceramic material to look for that give the best insulation for cups? Stoneware? Porcelain? Earthenware? Clay?

[JBaymore]

The thermal conductivity of all the clays themselves is so close as to be almost the same. However the less vitreous the more pores in the body. Pores can equate to dead air spaces. Dead air spaces act as a tiny bit of insulation. So porcelain is on the least insulating side, and earthenware is (likely) on the best. But the differeneces are kinda' small.

But the dead air spaces also decrease the thermal mass of the cup....which could work against you.

More likely of impact is the thermal mass of the clay walls. The more mass of colder-than-the-liquid clay you have, the more heat energy will be transfered to the clay from the hot beverage. More total mass of clay means more and faster cooling of the hot liquid content. However, if you preheat the cup, then more HOT clay mass means slower coooling of the liquid...or if the cup's mass is actually hotter than the liquid... the more heat energy that goes INTO the contents before it then equalizes and then starts to lose heat to the surrounding environment.

The Specific Heat of all clays are very similar, and well lower than water's, so that aspect does not figure in much.

Additionally, thin walls will more readily transfer heat energy from the liquid to the surrounding air molecules than thick walls.

For keeping the liquid the hottest longest, try a thick walled stoneware form that has an enclosed shape, narrower at the tiop opening than at the belly of the form. And preheat the cup before adding the tea.

best,

...............john

PS: Porcealin, stoneware, and earthenware are all made of "clay".

[entropyembrace]

Try finding a double walled ceramic cup...having two walls with lots of airspace in between will give you the best insulation. Have seen a couple of the potters in Teaware artisans section of the forum make them.

[debunix]

What's your goal: keeping the tea hot longer, or keeping your fingers cool while the tea is scorching hot?

[Alex]

This probably isnt going to be the best thing but I've got a double walled glass from here.

http://jingtea.com/teaware/glass-teawar ... -cup-200ml

That keeps tea warm for a silly amount of time. Literally half an hour and its still drinkable.

It isnt that great to drink from though as it has a very fat rim. Fine for office work though or gaming when I tend to forget.

[hyakuraiju]

What's your goal: keeping the tea hot longer, or keeping your fingers cool while the tea is scorching hot?

Keeping my fingers cool. I always hold the lip and base rim of my cups after pouring, but the heat still manages to transfer evenly through some of them. Strangly enough, some of my thinner walled yunomi keep heat out better than some thicker ones. I'm also looking into buying a good coffee/tea cup, because they all burn my finger when holding the handle.

[debunix]

A double-walled carved cup like these by bonjiri might be just the thing....

[JBaymore]

......because they all burn my finger when holding the handle.

Is it the back of your knuckle(s) hitting the side of the cup or the front of the fingers wrapped around the handle itself?

best,

..............john

[edkrueger]

Starbucks sells some. Somayaki kiln makes some hand made ones.

[hyakuraiju]

......because they all burn my finger when holding the handle.

Is it the back of your knuckle(s) hitting the side of the cup or the front of the fingers wrapped around the handle itself?

best,

..............john

The back of my knuckles and outside of finger.