208. All About “Chimneys”: Hi-Grade System Tenon Engineering, Part 2

A little over a year ago I took a close look at the Standard System tenon extension, its purpose, function and changes made in its design over time. In that post, the wider tenons and reservoirs of the Patent, IFS and Eire eras were contrasted to the narrower versions that came along from the Early Republic era forwards. The earlier Standard versions Charles Peterson designed visibly allowed for more moisture to accumulate in the reservoir with less air turbulence and better condensation with their built-in funnel-shaped extensions than the square-end tenons and smaller, shallower reservoirs that followed from c. 1945 onwards.

Today on This Old Pete we’ll complete our look at System tenon engineering, looking at a part of the System that has caused confusion since its first appearance in 1891: that little screw-in, screw-out part at the tenon end of the mouthpiece on the De Luxe and Premier Systems. In The Peterson Pipe: the Story of Kapp & Peterson we describe it as a tenon extension, adding that in old “Pete Speak” factory jargon it was called a “chimney.” These days craftsmen at K&P refer to it as as a “condenser,” according to factory manager Jonathan Fields.

But what does this piece do exactly, and does it do that job effectively? Its purpose was sufficiently obscure by the 1980s that I knew several pipemen—myself included—who screwed it out and threw it away, as it seemed to be merely an added step in the cleaning process. In fact, it’s something almost remarkable to buy an older estate Premier or De Luxe and find the piece intact.

Knowing what it does and how well it does it leaves us with one more question: what should it be called? For help in all these deeply fascinating (!) questions I turned to three experts: renowned pipe collector and retired mechanical engineer Andy Camire; commercial pipe expert and managing director of K&P, Josh Burgess; and pipe artisan and arm-chair physicist John Schantz of Rocky Mountain Briars. But first, let’s look at the chief historical examples in the development of the part in question.


Unsmoked bone tenon extension, c. 1955,
from a hand-made STRAIGHT GRAIN

From the very first, as you’ll be able to see when the 1896 catalog reprint is issued by Briar Books Press sometime in the not-to-distant future, the top tier of System pipes had a funneled, screw-in bone extension, which was cut according to the size of the mouthpiece, bowl and mortise. It could be quite large in the case of an Oversize or “House Pipe” and was scaled according to the bowl in question. Bone was used until around 1963, according to the retired craftsmen at Peterson, at which time the factory switched to aluminum. Here’s a used bone condenser from a De Luxe 4B, also c. 1955:

Smoked bone tenon extension, c. 1955,
De Luxe 4B

The bone condenser’s temperature remains close to that of the vulcanite mouthpiece during smoking so that there is no gurgle during the break-in period. This, I hasten to add, is merely a noise and not moisture being sucked into the mouthpiece that I’m talking about. Over time, a bone extension can become sticky, and if not removed to clean on a regular basis, will fuse into the mouthpiece. It also colors almost immediately. I used to say that bone is the preferred material for these tenon extensions, but after hearing from the experts below I’m afraid I was forced to change my mind.

Aluminum tenon extension with cross vents,
Premier Rustic 309, hallmarked 1984

When K&P switched over from bone to aluminum they carried over the bone design, retaining the cross vents. These are drilled at 120° of separation. Brad Pohlmann, one of the great American carvers, told me at at the 2019 Las Vegas pipe show that he wondered whether these might create a cyclonic effect in the shank chamber (mortise + reservoir). In any event, this was the standard tenon extension until the early years of the Dublin era.

Narrow-gauge aluminum tenon extension, 1975,
Centenary X 339

The 1975 Centenary of K&P produced two refinements of the tenon extension. The Sub-System X 339 seen above has a rare narrow-gauge tenon extension that is glued into the vulcanite mouthpiece and not made to be removed. The engineering (unlike that on most System Premier and De Luxe mouthpieces) is also spot-on so that a pipe cleaner runs effortlessly through it from P-Lip to the end of the extension.  As the reservoir on the X 339 is fashioned like any other System, the chief difference seems to be the distance the extension descends into the reservoir (as it’s longer than the usual extension) and narrow gauge, which changes the air pressure into the mouthpiece. The pipe smokes extremely well, making me wonder why they didn’t continue the use of this type of extension.

The other tenon extension variation from the Centenary years is the gold-toned aluminum version seen in the banner photo. This was used on all Centenary Systems as well as subsequent Supremes for many years afterwards.

Aluminum tenon extension without cross vents,
Premier 306, hallmarked 2011

Sometime early in the Dublin era (1991-2017) K&P switched to an aluminum extension without the cross vents, a practice which continued until the gradual replacement of vulcanite P-Lips with acrylic P-Lips around 2017. At that time the tenon extension was abandoned all together, it being erroneously believed that acrylic couldn’t be tapped (threaded to accommodate the condenser). Vulcanite Premier and De Luxe mouthpieces were still fitted with condensers, but those fitted with acrylic were not. Beginning with the Pub Pipe in 2019, acrylic P-Lips were tapped and the original Premier and De Luxe mouthpiece engineering resumed.


This is a geeky post, even by my overwrought standards, so I’ll begin this section with what we think we know. Or at least, what I think I think I know:

Tenon extension or chimney. The screw-in funnel-shaped device that extends the tenon below the airway hole in the bowl of De Luxe and System pipes. Its purpose is to aid in condensing water vapor in pipe smoke and cause the condensate to fall into the reservoir. This dries and cools the smoke as well as prevents solid material (ash or tobacco) from entering the airway of the mouthpiece. If you’ve used a System pipe you know that the System does in fact work in this way when coupled with the P-Lip mouthpiece and a correctly-drilled reservoir. And if you’ve used non-System pipes you know that hot, wet smoke and detritus moving up the airway into your mouth are common problems even when made by artisans.

So much for provisional definitions. Let’s begin with advice on what to call this System piece from one of the great men in the US hobby, pipe collector and retired engineer Andy Camire:

“Tenon extension” is the term I like best, since there are a number of words that could be used to describe this part (it could be called a nipple or teat, which I would not like to suggest for obvious reasons) [Ed.: sigh].

“Chimney” is a term that I really dislike, because I view a chimney as something that smoke rises from, but here we have an extension that is used as a drain.

“Condenser” is another appropriate term, because this is actually what it does when it’s made of a metal substance. The acrylic extensions on the acrylic stems don’t condense vapor as well as metal and are not removable but still function as condensers.

“Fitment” or “nozzle” are two other terms that could be used in describing this part.

My favorite term would be “sprue bushing,” which means “a metal part turned on a lathe with a tapered hole.” A “Sprue” can be both the metal part and the plastic in liquid form that flows into the mold and then hardens. So the Peterson tenon extension, in my opinion as one who worked in the tool trade, is a Sprue bushing.Josh Burgess, with boots on Ground Zero of the Pete Universe at K&P as well as a long tour of duty in the commercial world-culture of pipes, helps out with how the tenon extension is denominated at the factory:

Oh dear. I fear that we are about to pass out of the realm of “Pete Speak” and into the realm of “Pete Semiotics” [the study of signs and symbols as they relate to Peterson pipes]. The referent would be that little piece of aluminum that screws into the end of the stem on Premier and Deluxe Systems. But I don’t feel confident enough to settle on a reference yet. Here’s the story of my experience with that object:

When Laudisi first began developing manufacturing software for Peterson, someone had to create part names and SKUs in the new software that corresponded to what was in the old software. Everything that went on a pipe—every bowl, ring, stem, band, filter, or whatever—had to get created as an “input” in the new software. Glen Whelan [director of sales] and I did most of that work because we were sort of standing in the middle between the factory and the programmers. When I was working on my list of items, I came across something from the old software called “SCREW.”  I went to Jonathan Fields and Joe Kenny out in the factory and asked, “What the hell is this?” This was the part name being used in the old software and it seemed to be what was current in the factory to describe our referent. That made a certain amount of sense, as it screws into the tenon. But “SCREW” also seemed really terse and too vague. So I needed something more—a descriptive name for that part that I could use for the title. I’m not sure who threw out “condenser” —it could have been me or it could have been Jonathan or Joe. I wish I could remember, because if it did come from Jonathan and Joe that would suggest that it had some currency in the factory as a referent prior to Laudisi. But “screw” and “condenser” were the common terms in 2018 and 2019, and they were widely used in the factory. As I became more familiar with your work on Peterson history, I noted that “chimney” had been the traditional Peterson name for that part, and I began making a concerted effort to reintroduce that term, with limited success I think.

“Condenser” is problematic in certain ways because we tend to think of condensers as having a specific function—to cool gas and turn it into a liquid. Here’s what I feel certain of: no one on that day that I asked for someone to explain to me what the “screw” was believed or intended to convey that the little part in question technically functioned as an condenser. I think what was intended there was to say that the part condensed (as in reduced or made smaller) the external dimensions of the tenon down to a little cone.

So that part has been referred to in a variety of ways—“chimney,” “screw,” “condenser.” Screw-in Tenon Extension is probably the best technical description that I can come up with. But the other terms are pithier, and those seem to be the ones that stick.I saved Pete Freek John Schantz for last as I wanted to get you get toughened up mentally as we went along. You may nevertheless want a fresh cup of coffee before proceeding. There’s a reason Peterson is known as “the Thinking Man’s pipe,” and you will need all your grey cells operating at full capacity to finish this successfully.

John’s comments have helped me begin to understand the science behind Charles Peterson’s invention. Being John, he devoted an entire weekend to a System smoking marathon and measurements experiment. Here’s his summary of his findings:

I powered through more bowls of tobacco in one weekend than ever before. On the first day, I smoked two XL5s Dublin Briar in a Circle Systems, one from 1985 and one from 1988, first with a solid aluminum condenser and then with a cross-vented condenser. My 1985 pipe has a slightly smaller reservoir, mortise and bowl bore diameter but identical exterior dimensions.  I smoked C&D’s Dasher Wintertime Reserve and Sutliff’s Barbados Plantation and the condensers worked correctly, condensing moisture out of the smoke and allowing it to drip off the end of the condenser into the well. Both of these tobaccos, I might add, normally smoke wet for me. Surprisingly, the Sutliff was much less harsh than when smoked in a non-System.

I didn’t really notice a difference between the two types of condensers, which is maybe why Peterson cut the cross-drilling step out, thereby saving some manufacturing cost.

The second day I devoted to Standard System and non-System bent pipes. I smoked a 308 Standard with its built-in vulcanite tenon extension and it smoked as dry and smooth as the two De Luxe pipes with their aluminum extensions. I noticed, however, that the moisture did not build up into a drip, but did condense and fill the well as designed.  I should note that, to measure wet heel in the 308 experiment, I placed a Philtpad in the bottom of the bowl, but it stayed nice and dry. In non-System pipes, the Philtpad soaked after one smoke.

I also smoked a 2019 SPD System 313, which gave me some issues. It was only the second bowl I had smoked in it and I left the bowl coating as it was for the experiment.  As with the 308, I used the Philtpad to check for wet heel. The pipe smoked wet and when I dumped the dottle and ash, the Philtpad was moist, as was the heel of the bowl. I removed the bowl coating and tried again. This time it smoked much better, and when I dumped ash and dottle, the Philtpad and heel were both dry. The acrylic tenon extension on the SPD worked as well as the vulcanite extension on the 308.

I am not a physics teacher, so I don’t claim to be able to fully explain to you the fluid dynamics of Bernoulli’s Principle and the Venturi Tube which is at work in the condenser, but I’ll do my best. In a System pipe, the “Venturi Tube” has several parts: the reservoir, the Morse Taper mortise of the army-mount fit, the condenser and the graduated bore of the P-Lip.

The reservoir of the System pipe allows heated smoke and vapor to expand. The small hole at the end of the condenser reduces pressure, causing water vapor to distill on the cooler aluminum condenser, build up on its exterior and drip into the well. The smoke traveling through the condenser up the graduated bore is thus dryer and cooler.

I am not sure what the function of the condenser’s cross-vents is, unless perhaps they reduce the suction of the stream at the condenser tip so that any drips of moisture would have less of a chance to be sucked up into the stem. As I said earlier, I didn’t detect a discernible difference between the two types of condenser.

As for the name of this hardware, it could be called either a “tenon extension” or a “condenser.” Both are correct. As an extension it has a twofold function: first, it pulls the in-flow of air below the briar’s draft hole so the liquid drips into the well and not up the airway; second, it keeps ash and dottle out. The aluminum in the condenser acts to distill water vapor in the smoke stream similar to the way other manufacturer’s “stingers” do.  The constriction of the condenser is important in the drying process as it is the “venturi tube.” Whether made of vulcanite, acrylic, bone or aluminum, the condenser provides a surface for water vapor to be deposited on, build up and then drip off into the well. I think aluminum is probably best suited to the job.

When you notice a wet heel in a pipe chamber, you’re witnessing the chamber function incorrectly as a distiller. Correctly-functioning pipe distillers include expansion chambers like those utilized in a gourd calabash pipe, a reverse calabash briar and a K&P System (meaning the reservoir + [Morse tapered] mortise + condenser + graduated P-Lip mouthpiece). The parts of the System all work to get the water vapor out of the smoke by letting the steam expand and condense, falling into the reservoir.

K&P condensers and traditional stingers thus work as distillers, cooling the smoke and siphoning off water vapor. In non-System and non-calabash pipes (i.e., traditional tenon and mortise pipes) there should not be any expansion chamber from heel to stem.  If a pipe has a gap between mortise and tenon, then moisture builds up, hinders the airway and is ultimately sucked up the stem causing gurgle, unless there is enough room for the liquid to stay out of the air path. With a correctly-drilled pipe there should not be any space between the mortise and the end of the stem. When I drill my mortises, I use a brad-point bit which gives the end of the mortise a slight cone shape.  When I cut the stem, it gets an internal chamfer at a slightly larger angle than the point of the bit. Then I carefully trim the end of the tenon until the stem fits flush with the shank, self-centering on the cone shaped mortise.  This creates a zero gap and perfect airway alignment with no place for the smoke stream to expand, condense and drop out water vapor.With what these experts have said, I feel tolerably comfortable revising the “Identification Guide” entries as follows:

condenser  see tenon extension

tenon extension  the threaded funnel attached to the tenon of a System De Luxe or Premier, originally made of bone and then after c. 1963 of aluminum. Cross-vented until c. 1995. It resembles a sprue bushing from the world of injection molding but operates as part of the System’s four-part condenser, which includes the reservoir, Morse taper mortise, tenon extension and graduated bore P-Lip mouthpiece. This system dries and cools smoke as well as prevents solid debris from moving up the mouthpiece. Standard Systems include a built-in tenon extension which was funnel-shaped until c. 1937 and square-ended after. All Systems perform this condensing function, although the screw-in extensions create a higher-performing Venturi Tube based on Bernoulli’s Principle.

I am certain there are readers who know much more about this than I do, and while I am relying on John, Andy and Josh to correct my mistakes, if you can illuminate or otherwise offer any clarifying insights, please do. in your comments below Everything you see in this blog can potentially be used in the next Peterson book and it would be fantastic to get the science right.


Many thanks to
John Schantz
Andy Camire
Josh Burgess
for their invaluable insights



I recently acquired this beautiful XL339 Straight Grain from Mücahit Çakici, an economics major at the University of Siena. He’s from Turkey and has connections with Bay Pipe Meerschaum, home of carver Emre Mangaltepe.  Mücahit offers some really lovely estate pipes meticulously and offers DHL service with tracking. For Meer lovers, his friend Emre at Bay City Meer has pioneered a fascinating new tenon-mortise system which utilizes a briar ring pinned and glued to the mortise, which allows a traditional briar tenon-mortise push, as you can see here:

You can check out their pipes here:

Mücahit’s Instagram account for pipe selling

His Instagram pipe appreciation account

His eBay site

Emre’s Bay Pipe Instagram

Emre’s Bay Pipe Meerschaum

Continue Reading208. All About “Chimneys”: Hi-Grade System Tenon Engineering, Part 2