Is this porcelain that has been well-fired and is suitable for use in the microwave?

In this quick video, Antoinette demonstrates how to whip up a breakfast bowl in the microwave using a small porcelain casserole dish she renamed as  her “brunch-lets.” The porcelain handles remain cool while warming up in the microwave because the clay has almost no absorption, thanks to its vitrification process during firing.  

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​The video  highlights the risks of using ceramic or porcelain dinnerware in a microwave, specifically noting that porous clay bodies can trap water, causing the item to overheat while the handles remain cool. The speaker recommends porcelain (specifically referencing bone china/white clay) as the best medium for durable, high-quality dinnerware. Moving forward, the discussion will focus on clay and glaze chemistry to ensure safety and quality, noting that technical challenges remain in creating ideal, chip-resistant, and microwave-safe pieces

Examples of Antoinettes  brunchlets

Defining Brunchlets:
​Antoinette came up with the fun name “brunch-lets” for these little casserole dishes—they’re so much more than just egg cookers! These bowls are perfect for making a full breakfast, lunch, or a quick snack for one person. ​

One of Antoinettes earliest brunchlets, resembling an egg cooker.

Cup-sized brunchlets with long handle, large enough for a single meal in the microwave.

Cup sized brunchlet with two handles like a regular casserole dish, suitable for the microwave.

What are the primary distinctions between hard-paste porcelain, soft-paste porcelain, and bone china? ​​

Kinds of porcelain 
Historically, there are three types of porcelain: hard-paste porcelain, soft-paste porcelain, and bone china.
Hard-paste porcelain is made from clay that becomes glass-like when vitrified. It primarily consists of kaolin, silica, and Feldspar. The firing temperature of the clay depends on the temperature range of the Feldspar, and it is typically fired between 1200-1400 °C.

Antoinette, a renowned potter, teaches many potters worldwide in either online or hands-on classes to work with porcelain clay.

Soft-paste porcelain was developed in Europe during the time alchemists were searching for porcelain, which was originally imported from China. It was made from fine clay, sand, and glass. Unlike earthenware, soft-paste porcelain does not withstand high temperatures and will begin to collapse before reaching vitrification. It was often used for making ornaments.
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Bone china was developed in England when cattle bones were used to enhance the properties of soft-paste porcelain. The result was a very dense, strong, and glass-like, white, and translucent material. Historically, bone china contained 25% clay (kaolin), 50% bone ash, and 25% Cornish stone. In modern times, bones are replaced with a synthetic calcium phosphate, specifically dicalcium phosphate or tricalcium phosphate, which serve as powerful fluxes. Some artists, such as John Shirley, create artistic bone china bowls. Most people recognize bone china as the dishes displayed on their grandmother’s special shelf, commonly referred to as “chinaware.”  
There are other porcelain types that came along later, like Belleek porcelain, which is still crafted in Belleek, Ireland. America really helped shape this porcelain, and I’m writing about it in my book that’s still in progress. Also, there’s parianware, which is a different kind of porcelain made to be used without glaze, which I addressed in one of my Ceramic Monthly articles. Curtis Benzle creates his own version, so he can leave his sculpted bowls unglazed. 

This porcelain casserole dish, designed by Antoinette Badenhorst, is great for microwaving and, under specific conditions, can also be used in the oven. Antoinette is also a porcelain instructor at TeachinArt.com

John Shirley, a teacher at TeachinArt.com, makes beautiful bone china vessels by painting them with soluble salts to create vibrant colors.

Curtis Benzle, a teacher at TeachinArt.com, has created a porcelain piece that’s quite similar to parianware. He’s also using the Japanese Nericomi techniques to bring out the luminosity and color in his work.

Clarifying some terminology

Vitrification
Porcelain turns into vitrified glass when it’s fired for a long time at a high temperature, which fuses the clay particles into a dense, non-porous material. When the clay has a .01% imperviousness, it becomes food safe. This glassy bond keeps liquids from seeping into the handles, so there’s no steam buildup that can burn your hands when you use it in the microwave.
Besides making it microwave-friendly, this also makes it more durable because steam inside the walls of pottery can shorten its lifespan. 
Just a heads-up, porcelain can get pretty hot, as the heat from your food will transfer to the bowl or cup. That’s why handles are so important—they let you grab it safely from the microwave.

Water absorption in clay
If your pottery isn’t watertight, it might mean it needed a higher firing temperature to make sure the clay particles fusetogether. Or, if it was fired at a lower temperature, the melting agents (fluxes) should have melted at a lower temperature too. If the glaze doesn’t fit perfectly, liquids can also sneak into the clay. You might see tiny cracks on the ceramic container. When liquid seeps into the clay walls, it can take ages to dry out. So, if you use it in the microwave, steam might escape and burn your hands. Also, if you wash it in a dishwasher, harsh chemicals could damage it. The real danger comes when bad bacteria from dirty dishwater gets into the clay walls.

Bone China Versus Porcelain 
Bone China, because it is not plastic enough, needs to be slip cast, while all pottery techniques can be used to create porcelain. 

Recipe for Creme Brûlée in a brunchlet: ​
Enough for 4 servings: 
3 large eggs
3 table spoons of sugar
3/4 cup of cream
1 teaspoon Vanilla essens
A pinch of salt
Instructions: 
​Mix all ingredients together and divide in 4 brunchlets
Place in the microwave for 45 seconds. Stir and put back for another 30-45 seconds ( different microwaves will cook differently)
Sprinkle sugar or spread a jelly of your choice on top. Place under broiler until golden brown. 

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