The Egyptian hieroglyphic sign for 'write' was formed from an image of the scribal palette and brush case. Statues of scribes are sometimes shown with a papyrus across their knees and a palette—the scribe's trademark—over one shoulder. Two examples of the scribal palettes are preserved in the British Museum (EA 12784, EA 5512).
"From the late Old Kingdom on, the basic palette was made of a rectangular piece of wood, with two cavities at one end to hold cakes of black and red ink. Carbon was used to make the black ink and iron-rich red ochre to make the red. Both pigments were mixed with gum so that they congealed rather than turned to dust when they dried. The cakes of ink were moistened with a wet brush, rather like modern watercolours or Chinese ink. Brush-pens were made of rushes, the tip cut at an angle and chewed to separate the fibres. These were kept in a slot in the middle of the palette.
"Black was the normal colour for writing. Red was used to mark the start of a text, or to highlight key words and phrases, like quantities in medicines, or for the names of demons in religious papyri. More colours were needed for illustrations, such as those in the Book of the Dead" (http://www.britishmuseum.org/explore/highlights/highlight_objects/aes/t/two_scribal_palettes_with_ink.aspx, accessed 07-11-2009).