Underglaze pencils are great for people who like to draw graphic images or create painterly effects on their ceramic surfaces. Here’s how to make your own
General information on underglaze pencils
Commercially available underglaze pencils or crayons usually come in a very limited range of colours but you can easily expand the colour range by making your own from a combination of refractory materials and ceramic stains or oxides which are generally low fired to equal an HB pencil, although you can fire them to higher or lower temperatures for more specific uses
Gather together all the materials you will need to complete the project
It’s easier if everything is to hand before you begin
You will need:
■ Gram scales
■ Bowls for mixing
■ Slip ingredients as in the recipe below
■ Dust mask
■ 80-mesh sieve
■ A selection of coloured body stains
■ White-firing ball clay 50
■ Potash feldspar 25
■ Silica 25
■ Bentonite 5% added for dry strength in the green state
■ Colourant 15% maximum
Note: some colourants are stronger than others, giving great potential to make pencils in varying shades
■ Sodium silicate or Dispex
■ Small plaster batt
■ Rubber kidney
Following the recipe, weigh out the ingredients individually then transfer them to another bowl for mixing – this way, if you make a mistake it can easily be rectified.
Wearing a dust mask, thoroughly mix the dry ingredients together to break down any lumps that may be present. It is very important that the bentonite is completely mixed into the other materials before adding water.
Dry sieve the ingredients through your mesh for thorough blending.
Measure 1% sodium silicate or Dispex and add it to 45% water for each 100g of dry materials.
This will intensify some colours but essentially give additional green strength to the slip for forming into pencils later
Still wearing your dust mask, add the dry ingredients to the water and mix well to a thick paste.
If you think the mixture needs it, sieve it again through the mesh. This will give perfect colour distribution.
Sieve directly onto your plaster batt if possible – this should be easy with such a small amount of mixture.
Spread the mixture out evenly over the plaster batt with a rubber kidney and leave for a few minutes for the slip to firm up.
Turn the mixture over on the batt to allow it to firm up evenly. Old store cards are perfect for this type of task.
Try to avoid cutting into the plaster to avoid contamination.
When the mixture has firmed up to the point where it can be handled, knead it until it’s smooth and pliable.
You will only be able to use your fingers to knead such a small amount!
Roll the mixture into a coil about 5mm thick (or your preferred size) then cut it into equal lengths.
Leave the pencils to dry on the plaster batt then fire them to between 800°C and 950°C, depending on how hard you want the pencil.
A lower firing will give a soft, pastel-like pencil, higher firing will result in a harder pencil.
TIP: You can see from the final image that a 100g mixture will make quite a few pencils, so you may prefer to split the mixture to make two or even three different colours.
Weigh all the dry ingredients except the colours to do this. Dry sieve the ingredients then weigh them again to divide the mixture before adding your colourant to the split amounts. Similarly, mix the full amount of water and sodium silicate then divide the amount and add accordingly.
This project was first published in issue 19
For more step by step guides, visit our How to pages