Things around us 7:
Science of pencil
Sharpen your life always; even though it will come to an end like a pencil, we have to keep on writing.
– Munia Khan
A pencil is a simple instrument that every one of us has used and is still using. There is a lot of science that we can learn from a pencil. Pencil is derived from Old French pincel, from the Latin word penicillus which refers to "little tail", which originally referred to an artist's fine brush made up of camel's hair, now it is used to refer to the pencil that we use to write, draw and mark, It better to know the origin of the word. This article will not be a fully scientific write-up but the facts and observations are accurate.
What is a Pencil?
This is not a question from an exam but it is an open-ended question so any answers mainly casual and informal answers are expected. According to many, a pencil might be anything with which we can write on some surface a piece of charcoal, a beetroot, clay, dirt, chalk, brick, and many more such items can be considered as a pencil. So the principle or mechanism of writing is the same in every item, in simple words a very thin layer of the material that is used to write is deposited on the surface on which we write. So I call anything that follows this mechanism a pencil in a very rough manner.
What is " the so-called modern pencil"?
Our main focus is on the pencil that we use at present. They obey the above mechanism of a pencil but why are they called modern is a good question to ask. It is just the who industries made modern wooden pencils which made many differences in the economy, environment, and art.
The form of pencil that we use was invented in 1795 by Nicholas-Jacques Conte, a scientist serving in the army of Napoleon Bonaparte. There are many things associated with a pencil from the name graphite to environmental sustainability.
The dark material that was so appropriate for the purpose is the form of pure carbon that we call graphite. Initially, the form carbon graphite was believed to be a form of lead (An element in the periodic table) and was called ‘plumbago’ or black lead. It was called graphite only in 1789, using the Greek word ‘graphein’ meaning ‘to write. So carbon got its nickname graphite due to the use of pencils.
The purest graphite deposits were found in Borrowdale near Keswick in England in the Lake District in the 1560s. They spawned quite a smuggling industry and associated black economy in the area. During the nineteenth century, a major pencil manufacturing industry developed around Keswick to exploit the high quality of the graphite. It is a little odd to think the pencil industry made an underground economy and started a black market in the raw material industry.
Structure of a pencil
The outer cover of a pencil is mostly made up of softwoods which are coniferous trees, such as pines or spruces. Cedarwood and Pulai Wood are most commonly used in pencil production. Generally, these are soft wood with straight grains.
The inner core part of a pencil the graphite or commonly called lead is made from a form of carbon called graphite. Chunks of graphite and clay are used to make the central lead of the pencil. The pencil core is called a lead because of its appearance of dark gray color but in reality, the element lead can't be used to make the "lead" of a pencil. This is the basic structure of the pencil.
How pencils are made in industry?
Once the trees are ready they are felled and logged, they are cut into blocks about 19 centimeters long–the average length of a pencil. This block of wood is sliced into thin “slats,” which are then treated to make the wood dry and soft. This will help make the pencils easier to sharpen in the future. After resting for 60 days, the slats are ready to be made into pencils. Parallel grooves are carved into each slat to fit the “lead” or graphite rod. A special type of glue is squeezed into the grooves to keep the graphite in place. Before insertion into the slats, the pencil leads are put into an oven and heated to 980 degrees Celsius. The intense heat makes the leads smooth and hard, which results in good writing tips. The graphite rods are squished into the slat on top of the glue. A new slat is placed over the top of the first slat, sandwiching the graphite in the middle. This sandwich is heated and pressed hard, turning the two slats into one piece. The sandwich is cut to produce individual pencils. A standard pencil diameter is 7 millimeters. The pencils are painted, varnished, sharpened, and stamped. Chunks of graphite (and clay are placed inside a huge rotating drum. Large rocks inside the drum crush the graphite and clay into a fine powder. Then water is added, and the mixture is blended in the drum for up to three days. A machine squeezes all the water out of the mixture, leaving behind a gray sludge. Huge wheels grind the dried sludge into a fine powder, and water is blended in to make a soft paste. The paste is pushed through a metal tube and comes out in the shape of thin rods. The rods are cut into pencil-length pieces.
Understanding science from a pencil - How does the graphite stick on the writing surface?
To know this we need to know some interesting properties of graphite and paper.
Graphite is one of the naturally occurring substances of carbon along with diamond and coal, all three are only made no of carbon but their properties are entirely different due to their arrangement (this interesting fact will be later examined in a separate article). Graphite has a layered structure that consists of rings of six carbon atoms arranged in widely spaced horizontal sheets. It consists of sheets of trigonal planar carbon. Each such individual layer is called graphene. In each layer, the carbon atoms are arranged in a honeycomb lattice. So typically it looks like a stacked honeycomb. Bonding between layers is relatively weak van der Waals bonds which are the weakest of all the molecular bonding and are often occupied by gases, This type of weak bonding allows the graphene-like layers to be easily separated and to glide past each other thus they are easily separated in fine layers of sheets which in most of the case seems to be a powder. Simply the whole idea is that by applying a very small pressure then graphene can be made into very fine powders which are sheets of graphene.
Paper is a good thing that is existing. A paper seems to be smooth and soft but a paper has much more potential than we think. Paper can cut through our skin and can even break glass when it is used properly. Looking through a microscope we can find that paper is like a bunch of cottons tangled together. So many things can easily trap the fibers of the paper and the surface of the paper is not very smooth therefore there are lots of ups and downs in it which makes it good for trapping molecules.
When you write or draw with a pencil, tiny pieces of pencil lead stick to the paper and make a mark. Each tiny piece of pencil lead is made up of many molecules of graphite. Graphite molecules are flat groups of carbon atoms that are stacked in layers. The layers slide against each other and allow the lead to slide off the pencil point and onto the paper. Therefore the molecules of graphene make a mark on the paper. Well, it seems to be simple but it is exciting.
Backspace your mistake
We can easily rub off the pencil mark on paper with a rubber. The pencil rubbers are not like the rubbers in tires or any other instrument they are a little different make they are sticky and can form tiny layers upon applying friction. Erasers pick up graphite particles, thus removing them from the surface of the paper. The molecules in erasers are 'stickier' than the paper, so when the eraser is rubbed onto the pencil mark, the graphite sticks to the eraser preferentially over the paper. Some erasers damage the top layer of the paper and remove it as well. Erasers attached to pencils absorb the graphite particles and leave a residue that needs to be brushed away. This type of eraser can remove the surface of the paper.
Before the eraser was invented, you could use a rolled-up piece of white bread (crusts cut off) to remove pencil marks, and interestingly the application of the substance that we call a rubber got its name from this application of rubbing of the pencil marks.
Hexagon, pencils, and atoms
hexagon is a regular six-sided shape. Most of the pencils that we use are hexagonal. There are a few interesting reasons for that.
A pencil is made up of logs of wood. With a standard block of wood, one can make around 8 pencils if it is circular or of any other shape. When the pencils are made in a hexagonal shape with the same log one can make 9 pencils which is a huge profit on a large scale. This is science when we study the atomic arrangements or packing of atoms and molecules. There is mainly two basic packing structures cubic closed packing (cpp) and hexagonal closed packing(hcp), this is how most of the atoms and molecules are arranged in this way as an extension of this way. So, copying nature brings us lots of advantages.
As a science student some of you might have this doubt, CPP is more efficient than hcp then why hcp is used? The answer is simple, no one will like a square pencil on their hand which will heart them so hcp is preferred in this case. This may be a very lucid explanation of atomic packing yet useful to understand why we need to study them to make our lives better. Philosophically it gives a few good reasons which I leave open for you to explore.
A little wisdom on the markings on pencil - HBF (not HBO)
Pencils are used to have short abbreviations in the following order: 9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, 6B, 7B, 8B, and 9B. What does it mean? It is mentioned above on the hardness scale, where 9H is the hardest one, and 9B is the softest pencil. The H stands for hardness, and the B stands for “black,” which gives characteristic shades. So, HB in the middle of the scale means medium hard pencil. The F means firm. Soft pencils can be easily rubbed, giving dark shades, while the H-ones are much more challenging to be removed from the paper. B-grade pencils have a soft lead, so they are the best pencil to ensure the best shades while sketching. Hard pencils are usually used for technical drawing, while soft pencils are more popular while artistic drawing. The lead inside the pencil consists of a mixture of clay and graphite to get different hardness. The more clay is added to the lead, the harder the pencil is. Popular pencils can be refilled besides the classical pencil made of wood and lead. Refill graphites are not pure carbon-based materials. They are composed of resin and graphite, making them more durable and resistant to breaking. What about the shape of the pencil? Classically, its cross-section has a round shape, but one of the most popular is hexagonal next to the round. That shape makes it easy to handle and slices less in hand. Sometimes it has a fancier triangular or even less popular rectangular shape. For more technical use, the carpenter pencils are far from the shapes that we have pencils at home. The Carpenter pencil has a more flat, elliptic, or rectangular shape in its cross-section. They are facile to grip than standard pencils because they have a larger surface area. On the other hand, due to its shape, a carpenter pencil isn’t allowed to be sharpened just by a standard sharpener.
A single pencil can write up to 45000 words which are roughly 150 pages.
A very short introduction to the cutting edge science and pencil
Some studies show that people, especially kids, have oral habits, of which one of the most common is pencil biting. Among digit sucking and tongue thrust, it was widespread among 3-6 years old children, and studies also show that pencil biting is more prevalent among girls. Some people have an intense and unreasonable fear of sharp objects such as scissors, knives, needles, and pencils. This condition is called aichmophobia. So basically pencils can be used as a device in Psychology tests that relate to human behavior, mental health, and neuroscience.
Pencil brings back science as a promising material in many fields. It can be used as a tip in conducting probes, namely SPM (scanning probe microscopy). , graphite material remains the dominant active anode material used in lithium-ion batteries used in portable electronics. Graphite is also popular in the fuel cell industry, improving the devices’ efficiency.
A pencil can be used to separate hydrogen and oxygen in water (a simple DIY science).
Even though a pencil is made up of a soft material it is a very good conductor of electricity so don't use pencils to clean the power sockets.
