Difference Between China Clay and Calcined China Clay

China clay and calcined china clay are similar-sounding substances with one huge difference.

So, what exactly is the difference?

It’s pretty simple: 

China clay is a naturally occurring material that we mine from deposits rich in kaolinite (also called the china clay mineral). 

Calcined china clay is the fired-up version of china clay that we get from exposing and subjecting china clay to heat between the range of 1,000 and 1,100 degrees Celsius. 

But what is the result of this process?

That is exactly what I will break down for you in this blog!

We will explore the definitions of the two substances and understand the key differences that arise from their different chemical and physical structures!

Let us dive in!

China Clay vs Calcined China Clay: Table of Differences

• Quick Table of Comparison: China Clay vs Calcined China Clay
• What is China Clay?
• What is Calcined China Clay?
• Difference Between China Clay vs Calcined China Clay
• The Sharad Group: Your Reliable China Clay Supplier
• China Clay vs Calcined China Clay: FAQs

Quick Table of Comparison: China Clay vs Calcined China Clay

Short on time? I’ve got you covered!

Here’s a table of comparison you can use to find out which material is right for your use case: 

What is China Clay?

China clay is a naturally occurring type of sand that is rich in kaolinite. 

It is usually found in mines by china clay powder suppliers in the form of uniform deposits. These deposits have formed over millions of years of weathering processes. 

That is, they are deposits of kaolinite-rich soil that have broken off from larger rocks by elements like wind and rain.

Also Read: Your Complete Guide to the Types of Kaolinite

What is Calcined China Clay?

Calcined china clay is china clay that is heated up to a temperature between 1,000 and 1,100 degrees Celsius. 

Why is this done? To remove the crystallized moisture content that is present in naturally occurring china clay. 

The removal makes the resulting calcined china clay:

• More abrasive
• Shinier and whiter
• Resistant to electricity

So, we get a material that helps us expand the scope of the uses of china clay powder for different industries. 

While this already tells us how both of these materials are different, let me walk you through the key distinctions between them. 

Difference Between China Clay vs Calcined China Clay

1. Chemical Structure

The first difference between china clay vs calcined china clay is their chemical structure. 

This is also a direct result of the difference in the process of their formation.

China clay contains crystalized water molecules because these are found in kaolinite in its natural form. This also reduces its ability to absorb any more water. 

Calcined china clay is the refined version of china clay: it is china clay heated to remove its water content. Calcined china clay is thus “dehydroxidising” china clay in powder form.

2. Physical Properties

The different origins also result in both china clay and its calcined variant having very distinct physical properties. 

Here’s why: China clay contains water in a crystal form. This crystallized water can absorb any light that is directed at it. As a result, china clay appears as a translucent material. 

But calcined china clay is the result of firing pure china clay. And not just any china clay, a pure grade that comes from the best china clay powder suppliers who have refined it to remove all impurities. 

So, it’s already made from nearly pure white china clay. 

But here’s the thing: when it is heated, the water that might have absorbed light in china clay is removed from it!

So, calcined china clay appears:

• Brighter 
• Shinier
• More opaque

And this is the material that is used in the paint and paper industries: it makes paint last longer and paper appear glossy and smooth!

3. Harness and Abrasiveness

The chemical and physical properties of china clay make it very soft. 

That means it is a non-abrasive material, a raw material that you can use in large quantities without wearing down a machine.

However, since calcined china clay lacks any moisture after it is “fired up”, you get a very abrasive substance on your hands. 

So, if you want to use calcined china clay, you will need to do one of two things: 

• Work with machinery that can withstand a lot of wear and abrasiveness.
• Use china clay if you absolutely cannot use an abrasive substance. 

4. Absorption and Porosity

The molecules of the china clay mineral – kaolinite – are bound very close together. 

That means they don’t have any distance between them that can be occupied by a new material, such as oil. 

So, it has very low absorption rates. 

Calcined china clay, on the other hand, has a sponge-like particulate structure. This porosity makes it a highly absorbent material, especially when it comes to substances like oil! 

5. Electrical Properties and Reactivity

As we have seen above, china clay contains water in a crystal form. This means if you expose it to electricity, it will act like a conductor. 

And at high temperatures, its conductivity will become even greater!

So, if you are looking for a material that you want to use for wires and cables, china clay is the last clay type you should consider.

On the other hand, calcined china clay is a type of china clay whose moisture has been evaporated away via the process of firing. 

This makes it the opposite of china clay: an excellent insulator that will block any electrical current from passing through!

Calcined china clay is therefore the preferred material where the dielectric property is non-negotiable. 

For a more process-driven comparison, this guide to hydrous kaolin powder vs calcined kaolin powder explains how treatment changes the material’s structure and applications.

The Sharad Group: Your Reliable China Clay Supplier

China clay and calcined china clay are basically the same type of soil with one key difference: the latter is the fired version of the former. 

And this, as we have seen, makes a world of difference in their appearance, properties, and applications.

Now, the question is: which one do you need, china clay powder or calcined china clay?

This is where we at The Sharad Group can help you!

While china clay and its calcined version might be different, one thing that unites them is that we can supply you with high-quality supplies of both clay varieties!

So, connect with us as The Sharad Group, tell us about your requirements, and we will help you find the perfect clay for your operations!

China Clay vs Calcined China Clay: FAQs

1. What are the other names for china clay and calcined china clay?

While china clay is also known as kaolin clay (named after the mineral it contains), calcined kaolin is called metakaolin. 

2. What is calcined china clay used for?

The main use of calcined china clay is as a filler in plastics and paints. Plus, it is also widely used to manufacture the coating of wires and cables. You can also use it as a replacement for TiO2. 

3. Does calcined china clay absorb water?

Yes, calcined china clay absorbs water that is equal to its weight. However, it will not revert to china clay. Rather, it will only hold the water like a sponge, which you can remove by drying it.