How Tobacco Pipes Work

How tobacco pipes work

Pipes are simple devices. Reduced to their fundamental essence, they are blocks of wood with two holes drilled in them (we'll be concentrating on briar pipes without filters for our purpose here, though the concepts also apply to non-wood mediums like meerschaum). One hole is the tobacco chamber and the other is the draft hole, and the briar surrounding these holes can be in any or no definable configuration. A pipe is smokable with only these criteria, even without a stem, and all of the additional designing and finishing that a pipe maker applies may elevate its efficiency and attractiveness but are unnecessary for its basic function.

Pipe making is a craft and is also an art form, and the simplicity of basic pipe design is similar to that of other art forms. Just as a Tom Eltang Ballerina is a piece of wood with two holes, Van Gogh's "Starry Night" is a piece of canvas with some paint. Both achieve far more than the sum of their parts despite the lack of complexity in their rudimentary constitution. Their creators apply artistic vision to achieve the sublime. Much more than lowest-denominator function is employed in these compositions.

Still, their basic physical properties and interaction with physical reality must be understood. While Van Gogh's medium depends primarily on the reflection and refraction of light, Eltang's depends on functionality first and creative form after. A pipe, no matter its beauty, must first work well as a combustion device for tobacco; no matter its attractiveness, it is not a pipe unless it works.

A pipe, no matter its beauty, must first work well as a combustion device for tobacco

The Parts of a Pipe

The parts of a tobacco pipe

For a discussion about the way briar pipes work, particular terminology should first be clarified:

  • The tobacco chamber is easily identified; it's where the tobacco becomes smoke and ash.
  • The bowl is generally the largest part of the stummel and contains the tobacco chamber.
  • The stummel comprises the bowl, the shank, and the transition between them; for a briar pipe it's usually all one piece of briar and is essentially all of the pipe except for the stem.
  • The shank connects the bowl of the pipe and the stem and is usually smaller than the bowl. The end of the shank contains the mortise, into which the tenon of the stem is inserted.
  • The lip button is the expansion of the stem at its termination where the smoke emerges, making it comfortable to hold in the teeth.
  • The transition, as a general term, is the junction between the bowl and the shank of a pipe, but it is also employed to reference the shift from one element of the pipe to an adjacent area.
  • The draft channel: Also known as the draft hole or airway, it's the channel inside the shank and stem along their entire length from its entrance to the tobacco chamber to the termination of the stem at the lip button; it's where and how the smoke travels from the chamber to our taste buds.

The Pursuit of Perfect Airflow

Without oxygen, tobacco cannot ignite or burn to provide the flavorful smoke that we enjoy. Luckily, air is everywhere people hang out because we appreciate the advantages of oxygen as well, but pipe makers design avenues for that oxygen to work as an efficient cofactor in the combustion process. While a block of wood with two holes is capable of burning tobacco, improvements enhance the experience of smoking and transform it from an exercise in leaf ignition to a reasonably effortless and intuitive pastime to enjoy.

The concept of fluid dynamics, which includes gasses, is essential to great smoking pipes, beginning with the tobacco chamber. Every pipe is designed with smooth walls in the chamber, without protuberances, steps, ridges, or any other nonuniformities. The smooth walls are a protective measure as well as an element of efficiency. Any projections would be subject to fire damage, so smooth walls are essential. If a pit or fissure opened up on the surface of the tobacco chamber, it could easily progress into burnout and mission failure.

Flow graphic

Any obstruction to airflow produces turbulence that mixes the smoke and extracts moisture while generating particle friction.

The pursuit of smooth airflow is especially important for the draft channel, which is usually drilled to 3-4mm. Pipe makers promote smooth airflow in a variety of designs: Some create channels that maintain the same circumference throughout; some, as with Peterson pipes, employ a graduating bore for particular draw characteristics accompanying their System pipes; and others utilize a 4mm bore through the shank and 3mm in the stem. What's particularly helpful, though, regardless of diameter or configuration, is that the walls of the draft channel be smooth.

The reason pipe makers take such care in these details is to fight against turbulence. Turbulence is a chaotic change in flow velocity and pressure in which particles exhibit additional motion, friction, and heat transfer, and is the cause of one of the most irritating characteristics of a poorly made pipe: excessive moisture generation. When airflow is interrupted, moisture is deposited from the smoke to accumulate in the troughs of rough or angular surfaces.

Peterson System Pipe

Peterson System Pipe

That moisture is most often recognized by smokers as "gurgle." No one likes their pipe to gurgle. It not only sounds awful but interrupts the draw of smoke into the mouth in an irritating staccato performance. It is a signal that excess moisture has accumulated, and if a drop of that moisture migrates up the stem and finds the tongue, extreme disappointment will follow. Moisture produced by burning tobacco is perhaps the vilest tasting substance imaginable. More than a few beginning pipe smokers have abandoned the recreation because of that insidious substance, which tastes like undiluted despair.

Hence, pipe makers pursue techniques for reducing the chance of moisture generation. By preserving consistent draft channel circumference, for example, turbulence and its collateral moisture are vastly reduced. It isn't easy, especially since the comfortable flattening of the stem at the lip button is often less than the smoke hole's diameter: The height of the stem near its termination often cannot accommodate 4mm. Consistency is achieved by widening and ovaling the draft channel in this part of the stem and filing a "V" shape at the lip button, thus changing the configuration of the channel while accommodating the same volume of airflow and assuring that the circumference is consistent and turbulence is reduced. If the smoke hole is merely changed to a smaller diameter to accommodate the flat stem without smoothing the internal transition, turbulence and moisture can escalate.

Turbulence is additionally caused when the walls of the draft channel are not smooth. Every internal file mark and rough patch increases the potential for moisture. It can be kept under control by employing pipe cleaners to wick that moisture away, but even the most dedicated purist can be taken by surprise. Pipe makers will often polish the interior of the draft channel to maximize smooth airflow. If you've wondered why artisan pipes can be expensive, imagine the time invested in polishing the interior of a 3-4mm draft channel, among other heroic efforts.

Every internal file mark and rough patch increases the potential for moisture

Abrupt or excessive angles in the shank and stem can promote minor turbulence, so it's even more important to smooth the interior for these applications. In general, straight pipes will smoke slightly drier than bent pipes, though it's an almost imperceptible issue except where other more prominent airflow issues persist.

The Mortise and Tenon

The most common source of excessive turbulence and moisture is at the mortise and tenon. This is the internal area at the end of the shank where the stem meets the stummel. If the mortise and tenon are misaligned, turbulence is inevitable. When there is an excessive gap between the end of the tenon and the mortise, even if alignment is correct, that gap will collect moisture, pipe cleaner fuzz, and gunk. Cleaning this juncture under these circumstances is dissatisfying, but even worse is that the collection of gunk interferes with good smoking properties, negatively altering the flavor of the smoke.

When there is an excessive gap between the end of the tenon and the mortise, even if alignment is correct, that gap will collect moisture and gunk

If the end of the tenon is sharply flat with a gap between it and the mortise, it may be more susceptible to collecting moisture, especially when accompanied by misalignment. Many manufacturers round the end of the tenon to reduce airflow issues. Some artisan pipe makers routinely achieve perfect alignment and countersink the end of the tenon into the chamfered draft channel where it emerges from the face of the mortise, though it cannot be entirely without a gap because of expansion. When a pipe is smoked, heat, of course, is generated, and heat makes materials expand, so if the tenon is snugly countersunk it could push the stem slightly away from the shank. That circumstance does not affect the smoking quality of the pipe, but is nonetheless irritating. The smallest gap possible is preferable.

Precipitation graphic

Any obstruction to airflow produces turbulence that mixes the smoke and extracts moisture while generating particle friction.

However, there are pipes that easily overcome deficits in any of these areas, and the reason seems to be unknowable. Some pipes are constructed sloppily and look like they should smoke terribly but are admirable performers despite waving every red flag. Maybe it's an exceptional piece of briar. Maybe the owner happens to prepare the tobacco, load the bowl, and adjust their smoking rhythm in exact harmony with that particular pipe. It seems appropriate, though, that some mystery remain.

Optimum airflow is not necessary for a pipe to function, but it helps. The use of pipe cleaners and the drying of the tobacco before use alleviates most moisture problems, but even a poorly made pipe that performs very well would be even better if endowed with excellent airflow characteristics.

How a Pipe Works

All of these airflow considerations are a response to the basic way a pipe works. A vacuum is created at the end of the stem when a smoker draws on the pipe, causing air to enter the top of the bowl and mix with the tobacco. When there is an ember in the tobacco or a light is applied to the top, combustion transfers from one strand or particle of tobacco to the next level lower in the bowl. We all know that a pipe cannot be lit without drawing through it while applying flame, and we intuitively understand the necessity of creating a vacuum.

This phenomenon is why tamping is essential. As one layer of tobacco burns, the ember cannot transfer to the next layer without being in immediate proximity, and since tobacco expands as it burns, it must be tamped down for the ember to migrate into the tobacco chamber, keeping the pipe lit. When the vacuum is no more, it takes little time for the combustion in the bowl to extinguish. Airflow is essential. Without it, pipes would be doorstops.

Airflow is essential. Without it, pipes would be doorstops

Pipes are relatively simple devices elevated by the skills of seasoned craftsmen, who not only imbue each piece with attractive finishing, creative shaping, and enticing proportions, but carefully engineer the interiors for optimum airflow. When pipes perform their function correctly, and in addition are unique examples of the rarified artform of pipe making, they are cherished possessions, items that we are proud to own and appreciatively smoke. They are tools that capitalize on the basic physics of airflow, but much has been invested by thousands of craftsmen over centuries of experimentation to maximize the physics that support us in losing ourselves in the swirling, delightful smoke that emerges from a well-crafted pipe with superlative airflow.


    • Richard Favretto on June 12, 2022
    • I was hoping you'd mention tapered tobacco chambers and chamber depths which affect the way a pipe smokes.

    • Craig McHenry on June 12, 2022
    • Thanks for providing insight into the physics of pipe smoking. Within my small collection I have a couple that approach great smokes every time I light up. Most likely, improving my packing and smoking techniques would bring them to perfection. I think I could improve my collection by tamping down my pipe buying excitement and practicing more discipline inspecting the pipe components more than its esthetics.

    • SO on June 12, 2022
    • Thank you for another very informative article. What about the black-carbon coating used in new pipe chambers? It smells toxic, and I usually sand it out.

    • Slobber Box on June 12, 2022
    • An excellent and informative article, thank you. I would like to mention another source of moisture and it's introduction into the pipe that I have noticed in my smoking experience. There have been times, even while smoking dry crunchy tobacco, that I have felt moisture/spittle being drawn from my mouth back into the stem/draft hole, very subtle. Is it possible that after puffing and increasing the heat or temperature in the tobacco chamber at one end of the pipe could create a backdraft sort of phenomenon at the other end that meets the lips upon ceasing to puff? Maybe I'm imagining things, but I swear I can feel it happen from time to time when I'm drinking a beverage with my smoke or my mouth is salivating over the delicious tobacco.

    • Jim Donoghue on June 12, 2022
    • Great information. I love pipe smoking!

    • Oz on June 12, 2022
    • In response to Craig McHenry, aesthetics are important. I personally ask 4 questions of myself.1: Do I envision myself smoking this pipe, will it look good hanging from my mouth?2: Is it a well known maker or am I willing to take a leap of faith?3: Does it have the characteristics of a well made pipe based on photo or testimonial evidence?4: Is the weight and materials, not to mention price satisfactory?Generally if I can't reconcile those 4 questions, I look for a better pipe.By no means do you have to do this, I just try to get the best value possible for my bottom dollar.

    • Oz on June 12, 2022
    • In response to Slobber Box, yes, in the act of smoking pipes, we can find not just vacuum and air physics, but also small scale thermodynamics, basically put, Neutons 3rd law of "equal and opposite reaction" is what causes the spittle, even in a straight pipe, to flow back to the chamber. You draw a pipe from the mouth piece drawing in smoke, but you are also releasing minute amounts of spittle in this moment back into the pipe because of that conservation of energy as well as the fact that water actually is drawn to fire because of its oxygen content. When this comes back up the stem and mouthpiece it tastes terrible, (doesn't ash usually taste bad?) because tobacco, or really anything burning releases water vapor, thus you bring moisture in through the tobacco chamber from the environment, the burning tobacco produces water vapor, it gets trapped due to a vacuum under the burning tobacco above it because cold sinks and heat rises, then it gets moisture from spittle backdraw, then you make a fateful draw and it tastes like the devil's bunghole. I could have just said yes... sorry.

    • Slobber Box on June 12, 2022
    • @ Oz: Thank you for your response. It was entertaining and I enjoyed the science in your explanation. I can handle the undiluted despair, but the devil's bunghole...lolšŸ¤¢

    • Dirk Heinemann on June 22, 2022
    • @SO That stuff is called bowl coating and usually is made out of waterglass and medical level charcoal. It's totally safe, but of course some people just don't like the taste so no problem if you like to sand it out. :-)

    • Manuel Pintado on June 26, 2022
    • Appreciate having shared this detailed information.Been extremely helpful.

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