The grease pencil, a wax writing tool also known as a wax pencil, china marker, (or chinagraph pencil in the United Kingdom), is made of hardened colored wax

Wax

thumb|right|[[Cetyl palmitate]], a typical wax ester.Wax refers to a class of chemical compounds that are plastic near ambient temperatures. Characteristically, they melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents...

 and is useful for marking on hard, glossy non-porous surfaces such as porcelain

Porcelain

Porcelain is a ceramic material made by heating raw materials, generally including clay in the form of kaolin, in a kiln to temperatures between and...

, glass

Glass

Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...

, polished stone, plastic

Plastic

A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

, ceramic

Ceramic

A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...

s and other glazed

Ceramic glaze

Glaze is a layer or coating of a vitreous substance which has been fired to fuse to a ceramic object to color, decorate, strengthen or waterproof it.-Use:...

, lacquered or polished surfaces, as well as the glossy paper that is used for photographic printing

Photographic printing

Photographic printing is the process of producing a final image on paper for viewing, using chemically sensitized paper. The paper is exposed to a photographic negative, a positive transparency , or a digital image file projected using an enlarger or digital exposure unit such as a LightJet printer...

 (particularly for contact sheets

Contact print

A contact print is a photographic image produced from film; sometimes from a film negative, and sometimes from a film positive. The defining characteristic of a contact print is that the photographic result is made by exposing through the film negative or positive, onto a light sensitive material...

), x-rays, and for marking edits on analog audio tape

Magnetic tape

Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...

. It is also used to label theatrical lighting gels. It is often used as a construction or handyman's marking tool as it rarely scratches the surface it is used on. It may be used to mark a wet surface. They are also favored among some traditional artists. Due to its ability to write on glass, it is often used in chemistry labs to mark glassware.

This pencil is available in several forms. The outer casing may be made of wood (like an ordinary pencil) and sharpened with a knife or pencil sharpener

Pencil sharpener

A pencil sharpener is a device for sharpening a pencil's writing point by shaving away its worn surface. Pencil sharpeners may be operated manually or by an electric motor.-History:...

. Other types are covered in paper and sharpened by pulling a string, needing no additional tools to remain functional. More recently, it has been produced in propelling form, essentially similar to a clutch pencil but with a different lead.

This pencil is usually made from non-toxic opaque wax similar to a crayon

Crayon

A crayon is a stick of colored wax, charcoal, chalk, or other materials used for writing, coloring, drawing, and other methods of illustration. A crayon made of oiled chalk is called an oil pastel; when made of pigment with a dry binder, it is simply a pastel; both are popular media for color...

 but stronger. Marks made by grease pencils are resistant to moisture

Moisture

Humidity is the amount of moisture the air can hold before it rains. Moisture refers to the presence of a liquid, especially water, often in trace amounts...

 and can usually be removed by rubbing the marked surface with a paper towel

Paper towel

A paper towel is an absorbent textile made from paper instead of cloth. Unlike cloth towels, paper towels are disposable and intended to be used only once. Paper towels soak up water because they are loosely woven which enables water to travel between them, even against gravity...

.

Grease pencils can be found in many different colors.