Home >> Science & Nature >> Science

How to Make Fired Clay Float

Objects float due to buoyant force. Any object that is less dense than the water it displaces will float. To ensure your clay boat is less dense than the water, you must give it tall sides so that it holds a lot of air --- because air is less dense than water. Objects must also be non-porous in order to float. If the object is porous, it will absorb some of the water and this will increase the density of the object. Firing clay at high heat makes it impervious to water.

Things You'll Need

Clay
Roller
Kiln
Tub
Water

Instructions

- 1
  Roll the clay into a flat square. The square should be as thin as possible in order to decrease the density of the clay. This will be the bottom of your clay boat.
- 2
  Roll four separate pieces of clay that are at least half the height of the square's width. For example, if the square is 4 inches wide, the four pieces should be at least 2 inches in height. Carefully press one piece to each side of the square, making a box. Press the corners together. Roll thin strips of clay to place along the seams to ensure there are no gaps.
- 3
  Fire the clay until the boat is hard and impervious. Firing time may vary depending on the type of clay you are using, your kiln temperature and humidity. Allow the boat to cool before handling.
- 4
  Fill a large tub with water. Carefully lower the clay boat down onto the surface of the water. It will sink slightly, until the density of the boat displaces an even density of water. It will then float.

Science