How to Make Movable Metal Type of Goryeo: Beeswax Casting

Manufacturing of model characters is a very important process because that determines the typeface of a publication. Even more, types were used for a long time to publish many books once they were created. Famous calligraphers of the day were requested to write model characters, or or preferred font characters from existing publications were used as model characters.

After a strip of paper with model characters written on it is pasted face down on a bar of beeswax, slightly heated thin metal knife is used to rub the model characters onto the beeswax bar in order to make the two stick together.

Care must be taken when carving in relief because strokes of a character can be easily damaged due to the plasticity of beeswax. Because movable types are made by melting out beeswax characters and then filling the negative space left by beeswax with molten metal in beeswax casting...

 ...replacing a character would require making another beeswax model of the same character, which makes it impossible for the new character to be exactly identical to the first one. This is one of the evidences supporting the claim that Jikji was printed with movable types made by beeswax casting.

Heat is applied to one end of the beeswax rod to attach it to the back of a beeswax character. Beeswax rod is made in the shape of an awl, with the small tip attached to the beeswax character. If made thus, the pressure of molten metal at the rod’s wider end allows molten metal to flow smoothly into the negative space left by beeswax characters when molten metal is poured in. This will help separate movable type from the metal tree later.

The smaller beeswax rod with beeswax character is attached at regular intervals to the side of a thick beeswax cylinder that acts as the tree trunk. 100 to 150 beeswax characters can be attached to a beeswax cylinder at a time.

A thin coat of mold paste is first applied on the beeswax tree with a brush so that the mold will be completely filled, including the narrow space between the strokes of each character of about 1 cm in size.  

Bamboo molding flask is placed securely on the floor to immobilize it after a beeswax tree is inserted in it. Molding flask is made in a cylindrical shape to allow even distribution of heat throughout the mold when beeswax within is melted out in the kiln. Heat may not be distributed evenly in a molding flask of a different shape because heat flows in one direction in a traditional kiln.

Molding flask is filled with mold paste. Care is taken to avoid damaging the beeswax tree and to fill all space evenly between the tree branches.

Mold is dried in the shade for 20-30 days to harden it completely.

When beeswax is removed completely, a cavity is created inside the mold where beeswax used to be. This makes molten metal flow easily because runners are positioned downward.

Due to the fact that a small amount of metal is used at one time, metal is melted in a small furnace.

Metal is melted at a temperature of 1,000°C to 1,200°C.

Beeswax casting is a suitable method for making three-dimensional objects. More elaborate movable types can be made by it than sand casting.

Molten metal sometimes finds its way into gaps and form excrescences on the typeface if mold paste does not fill the molding flask completely and evenly.

Metal types attached to the tips of the metal tree are separated with a hacksaw or string.

Excess parts such as metal excrescences on newly finished movable types are removed, and the typeface in relief is then smoothed by rubbing them against a fine grinding stone. Care must be taken to avoid rubbing the typeface too hard as this leads to thicker strokes.

Because the size and shape of movable types are not uniform, types should be made similar in height, direction, and spacing, and they must be securely fastened during typesetting to prevent the types from moving. Once the initial typesetting is completed, a test print is run and the typeset corrected and reprinted according to the proof. This process of test printing and correcting is repeated three times or more for final typesetting.

Molten beeswax is poured on the printing block to fasten movable types, thus preventing them from moving when printing. Bamboo pieces or wet paper were also used in Joseon dynasty to stabilize movable types.

Oil soot ink must be used in movable metal type printing. Oil soot ink is made from the soot collected by burning vegetable oil. Common ink does not apply evenly to the metal surface of types; water droplets form on metal surface. For woodblock printing, pine soot ink is used.

Mulberry paper that has been cut into a specific size is put on the inked printing block.

A page is printed by rubbing the mulberry paper with a rubbing pad against the printing block. Rubbing pad is made of animal fur or hair tied together.

Only the required number of copies are printed per printing block. Extras are printed in consideration of possible mistakes that might occur during the binding process because it would be inconvenient to typeset the page again for reprinting later.