1. The Science of Raku

2. What makes fire? Fire happens through a process called combustion
You need three things for combustion
Do you know what they are?

3. Fuel You need something that will ignite
Anything that can burn can be a fuel
Wood, paper, oil, leaves, coal

4. Heat Source You need something hot to make the fuel start on fire
We use the glowing hot pots

5. Oxygen Fire needs air to breathe or else it won’t stay lit
Fire uses oxygen just like you and me!

6. What makes the glaze colors?
The main color in raku glazes comes from a metal called copper
Where can you find copper?

7. In Pennies…

8. The Statue of Liberty

9. What makes the color of copper change?
A chemical process called oxidation
Copper starts out the orange color like in a new penny
When copper is exposed to lots of oxygen in the air over a long time it turns green like the statue of liberty

10. Normal Copper Oxidized Copper

11. Oxidation and Reduction
In the kiln the copper doesn’t get oxidized, it gets reduced
The fire consumes the oxygen in the trash can and changes the color of the glaze
The reduced part of the pot will look red or like a copper penny
The oxidized part of the pot will be green or turquoise

12. Which side was reduced?

13. Which side was oxidized?

14. What makes the white glaze crackle?
The crackle comes from thermal shock
Thermal shock happens when a temperature changes from one extreme to another
The kiln is glowing red hot, but outside the air is much colder
This shocks the glaze and makes it crackle!

15. Where else can you see thermal shock?

16. Ice Cubes!
When you drop a frozen ice cube into a glass of water it creates thermal shock too!
The ice is so cold inside a freezer, but the water isn’t as cold
Thermal shock makes the ice cubes crack just like the white crackle glaze

17. This is only a small part of raku science
Get ready to learn even more when we fire YOUR pots!