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How to Test a Pencil?

A while ago I had an interview for the position of QA engineer in one IT company. They offered me to do a test task. The task was to describe the steps for comprehensive testing of a simple pencil with an eraser. In this article, I will tell you how I solved it.

Since pencils are generally the most wonderful and favorite topic, I got incredible pleasure from this task. In the process of thinking and searching for information, I discovered a lot of new and interesting things, something that I was not aware of.

So, let’s take a pencil. Since no additional information is specified we assume that:

  1. The pencil is not mechanical, but a simple one: wooden or plastic. They did not say anything about the color so it can be a colored pencil. This only says that this pencil is more suitable for expressive drawing than for simple note-taking or technical drawing. Let’s take this as insignificant as we will deliberately not consider testing pencils of different colors.
  2. Initially, we do not know whether the manufacturer sharpened the pencil at the factory or not, so let’s consider both cases.
  3. It is not possible to remove the eraser. It is located at the opposite end of the pencil.
  4. If we assume that we have only one pencil available, then testing cannot be carried out on all points – the testing functionality will narrow, because a pencil, is sadly not a recoverable resource: you need to sharpen it, write with it and do other interesting things.
  5. Nothing is mentioned about the packaging, manufacturer, and pencil characteristics. Let’s assume that we do have/know/see them. If the opposite is true, the testing functionality will be slightly different.

General criteria for evaluating tests:

The main evaluation criterion is the fulfillment/non-fulfillment of the testing conditions. If the test is performed, you can evaluate the result according to some predetermined rules (for example, on a ten-point scale, 0 is terrible, 10 is excellent; in general, the assessment criterion can be set as you like). In addition, we will try to represent some parameters in numerical terms. Based on the data obtained, you can create a summary of the characteristics of various pencil models.

Now, let’s take a look at basic test cases for testing a pencil.

Initial Properties of a Pencil Taken Out of the Box or Primary Testing

  • If the pencil is initially sharpened: make sure that you can use it to write. Some pencil manufacturers manage to sharpen them in such a way that they need to be sharpened again beforehand, because sharpened by default they simply do not write.
  • If the pencil is not initially sharpened: is it convenient for us in the current conditions to have a pencil that is not sharpened by default (for example, when there is no sharpener or stationery knife)? Is there a need for additional “initialization” of the pencil in the form of its preliminary sharpening?
  • Making sure that the eraser at the end of the pencil does not come off the first time you touched it and holds firmly – at least visually.
  • Is there a label on the pencil indicating (degree of hardness, core diameter, purpose, specific parameters)? Is the manufacturer listed?
  • What is the shape of the core: round, hexagonal, triangular, oval with a wide lead? In fact, pencils with a round body are more suitable for expressive drawing, hexagonal ones for writing, and technical drawing (in the first case, the hand gets less tired with a round shape, during writing and technical drawing – with a hexagonal shape). Pencils with a triangular body are suitable for children and people with disabilities – in cases when the hand does not hold a pencil well.
  • Is the body made of wood or plastic?
  • Is there a varnish on the pencil?
  • Pay attention to the box and packaging, as well as the marking on them: the manufacturer and all the characteristics of the pencil.

Quality estimation

  • There are no imperfections, stains from varnish, and other defects on the pencil.
  • The marking (if any) is done with high quality, the inscriptions are not blurry and are readable.
  • The eraser ferrule is even, does not cling to clothing and skin.

Usability Testing

  • The pencil is comfortable to hold. It does not slip and does not fall out during work.
  • Does the pencil have a so-called grip zone.
  • Special particles made of paint that prevent the pencil from sliding in the hand (2001, Faber Castell).
  • For the visually impaired: the use of pencils with a hexagonal or triangular barrel is relevant. A pencil with a round body rolled under a table is often a serious problem for a visually impaired person.

Functional testing:

Let’s draw something on paper.

  • Making sure that the pencil can draw.
  • Making sure that the color of the text/quality of the drawing corresponds to the hardness of the pencil (deep color, light, etc).
  • Let’s check the behavior of the pencil when you press the pencil lead on the paper. Make sure the pencil won’t break.
  • Pull the pencil lead. It must not come out of the body.
  • Tap the pencil on the table several times. The lead should not crumble or break, fall out of the body, or crack.
  • The lead does not break or crumble directly during drawing.
  • The pencil does not stain hands and clothes, does not leave additional marks on the drawing.
  • When drawing, the pencil body is clean, it does not collect germs and dirt from the hands. Best in this sense are pencils with a varnished body.

Using a pencil eraser.

  • How useful is the eraser on the end of the pencil ─ are you using it or it is more in the way?
  • It erases notes/sketches, does not smudge or make it “dirty”.
  • The eraser does not become hard over time and continues to perform its functions.
  • After use, the eraser does not leave crumbs, does not fall out; the ferrule does not bend or leave marks or scratches on paper and hands.
  • The pencil writes on the places where the notes were erased with an eraser.

Do the same with an eraser not taken from a pencil.

  • Now we will do some technical drawing, and then write with a pencil: all the same actions, but in slightly different initial conditions (before that we just drew). Different pencils are designed for different purposes: for school, expressive or technical drawing (more than 370 different types of pencils are produced in the world, so it leaves a lot of room for imagination).
  • Next, we will try to draw/write not on paper, but on alternative materials ─ thick paper, cardboard, newspaper, wooden block, walls, or floor (relevant for construction work).
  • Let’s draw through a carbon paper. There shouldn’t be any specific problems.
  • Storage and carrying: does the pencil fit in the pencil holder? How convenient is it to fit and carry in your pocket or bag? Doesn’t it puncture you at the same time, break or crumble?

ECO Testing

If the body of the pencil is varnished: what type of varnish is used: a polymer or water-based varnish?
This also refers to product safety testing. Unfortunately, it is impossible to find out 100% for all pencils because this is not always written on the box. Perhaps a chemical analysis will help.

This requirement is very relevant because very often children (and not only children!) Simply “eat” pencils. By my calculations, I eat a few pencils a year. How many harmful substances will I get from such a habit, if the pencil is not safe? Science does not know for sure. I could try to calculate, but I do not want to…

From the point of view of eco-friendliness, the best pencils are unvarnished and without an eraser (by the way, they are found in great variety in Ikea, Leroy Merlen, etc.). And for this reason I dislike pencils with an eraser at the end because if there is one, and especially with the iron holder – it’s inconvenient to chew on it.

eco testing

Security Testing

  • Can I get hurt with a pencil (scratched, cut when sharpening, is it dangerous for eyes)?
  • Is it safe to give a pencil to a child? There are “safe” types of pencils (for example, special “children” pencils, often with a triangular body) that can be given to children without fear (of course, depending on age, general development, and characteristics of the child).
  • Is the pencil safe for people with disabilities (eg visually impaired)?
  • Does the pencil comply with accepted standards (ISO, etc.).

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Appearance, Ergonomic, and Usability Testing

  • Pencil color. “Classic” yellow barrel in “Koh-I-Noor” style or alternative non-classic? When choosing a pencil, people are motivated by different things.
  • Overall appearance, layout, and design.
  • The body shape is round, triangular, or hexagonal.
  • The packaging/design brings or does not bring aesthetic pleasure and, in general, pleasing to the eye or not.

Here you can have additional data and draw additional conclusions: what is the potential target audience of buyers of this model, how well it will sell and in what places, what are pencil’s main marketing properties, is it necessary to promote, how much money should we spend on advertising, etc. I am not a marketing manager, but surely there are nuances but that’s another story.

Sharpening a pencil

Possible sharpening variations:

  • Sharpening with a pencil sharpener.
  • Sharpening with sandpaper (useful for soft pencils and pencils for retouching).
  • Sharpening with a straight razor.
  • Sharpening with a stationery knife.
  • Sharpening with a kitchen knife (cleaver, medical scalpel, etc.)
  • In the absence of sharpening tools, we sharpen (try) using unsuitable means (for example, teeth, a piece of glass, or a fork). As a result, most likely, there will be an epic fail, but nevertheless, it has a place to be.

Sharpening evaluation criteria (for each tool):

  • A pencil is generally sharpened with a pencil sharpener. For example, sharpening a pencil with a plastic body using sandpaper or a razor will be very difficult. Sharpening a very small pencil with a hunting cleaver will also be problematic.
  • Pencil sharpens easily. Quite a relevant test: some pencils turn out to be made of steel when trying to sharpen and cannot be sharpened at all (I experienced it with pencils of one well-known manufacturer).
  • During and after sharpening, the lead did not break its integrity.
  • During and after sharpening, the pencil does not break or crumble.
  • The pencil body does not delaminate, after sharpening there are no imperfections or other defects.
  • The lead does not fall out of the body.
  • For varnished pencils: the varnish does not flake off the body or crumble.
  • The sharpened pencil is successfully functioning (you can write, sketch, draw).
  • Calculation of successful sharpening coefficient K = M / N, where M stands for the number of successful sharpenings, N stands for the number of unsuccessful sharpenings. The lower the K, the worse is pencil-sharpening using this tool.

Then we act according to the following principle: break everything can be broken.

Stress Testing

  • Drop the pencil on the floor a couple of times and check whether the lead breaks or crumbles. The pencil body must not be damaged.
  • Try to bend the pencil: will it break or not?
  • Chew on a pencil. It’s advisable that the end of the pencil stays not “eaten”. Many manufacturers pay special attention to this point.
  • Place the pencil in water, then dry it.
  • Put the pencil in an acidic, alkaline environment for a little while.
  • Freeze and then reheat. Put in the snow in the cold.
  • Heat the pencil, then cool. But we will not set it on fire. This, of course, is also possible, although it is unlikely that after such a procedure it will be possible to use it unless you imagine a James Bond pencil that does not burn and does not sink.
  • If the testing budget is not limited or testing is well paid by the manufacturer for advertising purposes, we will conduct tests in zero gravity conditions. Astronauts on the ISS, by the way, use ordinary pencils.

Each of the manipulations described above will have a certain effect on the pencil. After each iteration, we test the use of a pencil (see functional testing) and sharpen it. We no longer test the appearance – there are suspicions that if you perform all the listed manipulations on a pencil, then it will no longer be a pencil, but at best some kind of its semblance.

Performance Testing, or, Finally, Some Simple Math

Let’s try to measure the performance of a pencil: how many pages of text/drawings it will last. Doing it manually will be a very long process since it is quite difficult to finish a whole (especially well-made) pencil. You can do all the operations manually, or you can use basic math.

Let’s imagine that there are some empirically calculated averaged indicators: how many pages of text/drawings can be drawn with a pencil of a certain length, hardness, a certain shape, and with a certain core diameter. Let’s call it “pencil efficiency” and it takes X A4 pages (or X miles of text) for a pencil of length Y cm. Let’s also assume that the empirical calculations are a little bit inaccurate as they use the whole pencil length, and since it is very difficult to use a pencil less than 4 cm long, plus around 1 cm for an eraser with a holder, we still have (Y – 5 ) cm. One sharpening “takes away” from a pencil about 1 cm in length, so for one pencil of a standard length of 18 cm, we have about 13 sharpenings. The pencil may break when sharpening. We count how many unsuccessful sharpenings were during the work of the pencil; let this number be equal to N. Let the length of the pencil be equal to L cm. Then:

Real pencil efficiency = (L — 5 — N) * (X/Y)

It can be assumed that after the pencil has already been sharpened by half, the number of unsuccessful sharpenings will increase in some way, for example, with the coefficient K. Then:

Real efficiency of a pencil = ((L — 5 — N)/2 + (L — 5 — K*N)/2) * (X/Y)

Another way is also possible: we will calculate the number of successful sharpenings, based on real data obtained empirically during sharpening of a pencil. Let it be V. Then:

Real efficiency of a pencil = V * X / Y

It is clear that the calculations are very arbitrary, and if you wish, you can make it more complicated and come up with more accurate criteria. The goal of the current example is not to accurately calculate the efficiency of a pencil but simply show that this measurement is subject to mathematical calculations.


You can think of a lot more. For sure. In the process of thinking about these actions, I actively used a regular pencil. However, without an eraser.

The test result can be presented graphically.

Alex Kara
By Alex Kara on Aug 28, 2021
Manual QA