DIY Thermal Pencil for Ceramic Underglaze Decoration

Sometimes a simple stroke of a pen leads to a nice and poetic decoration on a ceramic item. We can find ready-to-use thermal pencil in shops, but it can be fun to create some at home.

In this instructable I propose to create 6 colors pencils and try them under glaze at high temperature (stoneware clay support).

Step 1: Prepare the Materials and Weight the Oxides

Materials :

- plastic box

- big syringe

- spatula

- kitchen spoon

- newspaper

- analytical balance sensitive to 0.1g

- protection mask

- kaolin

- colorants : red, yellow and black ready to use high temperature colorants for ceramics

- oxides : cobalt oxide, red iron oxide, manganese oxide, copper oxide, chromium oxide

- kiln

Preparation :

BE CAREFULL : wear a protection mask while operating with powders !!

These are the ratio for each color, to blend each with kaolin :

- Black, red, yellow : 17g of colorant powder for 25g kaolin for each color,

- Blue : 5g Co oxide in 25g kaolin

- Green : 10g Cu oxide + 7gr Cr oxide in 25g kaolin

- Brown : 15g red Fe oxide + 11g Mn oxide in 25g kaolin

Step 2: Blend the Powders and Water

Wear a mask to do the blends with powders !

In 6 different plastic cups, for each color, put the kaolin, put the oxides, and add slowly water.

Blend with the spatula, and add water until the consistency looks like a creamy yogurt

Step 3: Prepare the Pencil

Wrap a small page of newspaper around the handle of the spoon, and fix it with a rubber, then remove from the spoon, in order to create a straw.

Fill the syringe with the creamy paste previously prepared, and fill the paper straw with the paste with the syringe.

Close one end of the straw and put it vertically for drying. The water will evaporate through the newspaper.

Clean very well the spatula ans syringe, and do it again for the other colors.

Let them dry, few days, when they are totally dried then remove the newspaper and fire them to bisque temperature (around 980°C)

Step 4: Try the Pencil at High Temperature : Check the Results !

On stoneware clay, try all your colors with drawings (it is in french, but I translated !)

Protect the clay with glaze and fire them. Here I tryied high temperature, 1260°C firing.

Check the results :

Blue, black and red colors are OK, green color became orange, brown color is very light and yellow dissapeared !

Conclusion : you can use these pencils for black, red, blue, light orange and light brown drawings at high temperature, and maybe it is worth trying these pencils at lower temperature on earthenware clay !