Crayons, Highlighters, & Other Writing Utensils | How It's Made | Science Channel

Crayon and Pencil Production Process

Crayon Manufacturing

• Crayons are a widely used drawing tool, with the average North American child using 730 by age 10. The first non-toxic crayon was invented in 1903 by an American Chemical Company.

• The primary ingredient for crayons is paraffin wax, chosen for its low cost and ease of melting. It has a good "rub off" quality, leaving sufficient wax on paper.

• To enhance durability, a secret powder is added to the melted wax mixture along with synthetic chemicals that prevent sticking to molds and improve rub-off properties. Colors are achieved by tinting the wax.

• A rotary machine injects the blended wax into molds, which are then cooled in water to harden within a minute. This machine can produce over 2,700 crayons per cycle, contributing to an output of 30,000 crayons per hour across multiple machines.

• After ejection from the rotary machine, crayons are labeled at high speed (12,000 per hour) before being sorted by color for packaging based on production requirements. Best-selling packs include sets of 16 and 24 crayons.

Pencil Manufacturing

• The lead in pencils is primarily graphite; its use dates back to mid-1500s England when it sparked the pencil industry’s development. A new type of lead was created in 1795 using graphite powder mixed with clay.

• Cedar wood from California is preferred for pencil bodies due to its softness for sharpening yet strength under pressure during writing tasks; slats arrive pre-cut for processing.

• Grooves are cut into slats to hold the lead securely; glue is applied to cushion the lead inside these channels and reduce breakage risk during use. Lead consists of a baked mixture of graphite and clay at high temperatures (around 1500°F).

• Colored pencils follow similar processes but utilize leads made from wax, clay, and pigments without baking involved; this results in different manufacturing steps compared to standard pencils.

How Are Pencils and Erasers Made?

The Pencil Manufacturing Process

• European-style pencils feature a rubber eraser inserted at one end, with the color of the painted cap indicating lead hardness.

• After applying a transparent sealer, pencils undergo multiple color dips before receiving a high gloss lacquer, ensuring both aesthetic appeal and performance.

• An eraser is essential for students to correct mistakes; white erasers are made from flexible vinyl while pink ones use synthetic rubber.

• The term "rubber" originated from tree resin used by South American natives to erase pencil marks; however, natural rubber rots over time.

• Charles Goodyear's curing process in the 19th century prevented rubber from rotting, leading to modern eraser production.

Ingredients and Production of Erasers

• Making pink erasers involves mixing synthetic rubber with fillers, accelerators, curing agents, oils, and coloring agents in a mill.

• The mixture is processed until it reaches dough-like consistency; then it's cooled and cut into squares weighing between 11 to 18 lbs based on thickness requirements.

• These squares are cured under steam pressure for about 20 minutes at 325°F before being submerged in cold water to halt the curing process.

• To create dual-purpose erasers that can erase both lead and ink, blue strips containing PMUs are paired with pink strips before pressing and cutting them into pieces.

• Finally, all-pink erasers are cut into beveled strips and tumbled in a barrel with talc to prevent sticking while rounding off edges.

Functionality of Erasers

• The ability of an eraser to remove pencil marks comes not just from its rubber composition but primarily from vulcanized vegetable oil which allows it to crumble effectively when rubbed against paper.

The Evolution of Highlighter Pens

Introduction of Highlighters

• Highlighters were invented in the 1960s as attention-grabbing tools using vivid inks like hot pink or warm yellow that draw focus due to their bright colors.

Manufacturing Process of Highlighters

• The manufacturing begins with plastic pellets being melted down; red dye is added during this process for coloration as it moves through heating tubes.

• Once molded into pen barrels under significant force (equivalent to 350 elephants), clear colored barrels are combined with polyester ink reservoirs resembling chalk pieces.

Ink Preparation

• A chemist prepares ink by mixing dye concentrate with water; precise measurements ensure optimal viscosity for smooth flow within pens.

Assembly Line Mechanics

• Mechanical vibrations assist in positioning nib components onto pens where they interlock securely while flooding the reservoir inside each pen with ink.

Final Touches

How Are 3-in-1 Markers and Ballpoint Pens Made?

Production of 3-in-1 Markers

• The assembly line for 3-in-1 markers involves a conveyor bowl that funnels smaller ink reservoirs into a shaft, where they are picked up by a robotic arm.

• A needle injects vibrant ink into the reservoirs, followed by another robot attaching a polyester nib and placing a hood-like cap over it.

• Metallic confetti is added to the markers using an electrical charge, enhancing their visual appeal before being sealed in triangular cases.

• The highlighters are then silk-screened with logos and undergo UV light treatment to bond the ink to the casing.

• A final quality test involves making circles; successful production requires each marker to complete between 700 to 1,000 circles.

Development of Ballpoint Pens

• The ballpoint pen was designed as a solution to issues faced with fountain pens, such as slow-drying ink and manual refilling.

• Injection molding is used to create plastic components for the pen's barrel and grip, ensuring precision in manufacturing.

• High precision machines shape stainless steel tips for the pens, drilling channels for ink flow and seating a small ball at the tip's center.

• Each cartridge undergoes rigorous testing for air pressure and movement accuracy to prevent clogging during use.

• The assembly process includes integrating internal components like push buttons that ensure even wear on the pen tip through rotation.

Quality Assurance and Final Assembly

• Random samples of pens are subjected to endurance tests simulating extensive usage (100,000 clicks).

• Fountain pens were revolutionary upon their invention in 1884 due to their built-in ink reservoir system compared to traditional quills or steel pens.

• Various filling mechanisms exist for fountain pens; one method uses a filler pump similar to syringes for drawing ink into barrels.

How Are Luxury Pens Made?

The Nib and Ink Feeder Assembly

• The nib of the pen is crafted from a durable metal in the Platinum family, with workers grinding the iridium tip to precise specifications that determine line thickness and style.

• The ink feeder is made from a cylindrical piece of Ebonite, which is cut to a point. Grooves carved into its sides regulate ink flow as they fill when writing.

• Technicians verify the final positioning of the nib under magnification, ensuring quality control before assembly.

External Parts Production

• In another section of the factory, sterling silver discs are shaped into pen caps using presses and metal drawing machinery. These caps not only protect the nib but also add decorative elements like intricate diamond-cut engravings.

• A rolling engraver applies branding to each cap, while clips made from beryllium copper are plated in gold for durability and aesthetics.

Barrel and Assembly Process

• The barrel and other components for many models are produced from plastic resin through an injection molding process that shapes liquid resin into solid parts ready for polishing.