381. Overcoming System Condenser Blockage & Drag: A Tutorial with Stephen Wilson and Gary Hamilton

If you’ve been companioning any of the high-grade Systems (DeLuxe, Premier, Pub & Handmade) for very long, you’ve undoubtedly run across a cleaning problem: getting your pipe cleaner all the way through the stem. I don’t have any Patent or IFS era high grades, so I don’t know if this was a problem way back then, but I do know that since the Éire era (c. 1937ff.) this has been the case: you push your pipe cleaner through the button and everything’s going fine until—wham!—it snags on the condenser (aka “chimney”).

Typical Condenser Block

I accepted the Condenser Block Situation as an opportunity to clean the tenon end of the stem so many years ago that I haven’t thought much about it until Stephen Wilson, CPG, began sending me emails last fall talking about a DIY fix. As he was still doing some R&D, I put off sharing his insights. Not long ago he wrote with his perfected technique, one that falls within the skill set of anyone who can hold and use a Dremel.

Gary Hamilton, CPG, dropped by this week for coffee and a pipe, and as like Stephen he’s also an articulate and insightful science-minded Pete Geek, I shared Stephen’s DIY tutorial with him, asking him to help me understand and visualize the problem of how blockage at the System condenser arises in the first place.  Gary, you’ll recall, already has quite a bit of experience thinking about tenons, as found in his work in Posts #322 and #290.

Just to be clear–because like you I’m learning as I go– we’re not talking about the lengthened built-in tenon extension on the Standard System, which is technically not a condenser–that is, it doesn’t condense moisture around it (as Shane Ireland explained several posts back).



Stephen: Nowadays I smoke Peterson bent System or DeLuxe System (including the Pub) pipes.  As you know, there is a bit of a challenge getting a pipe cleaner down the stem.  I have found that using Long’s Bristle cleaner works the best.  However, those pipes with the aluminum divertor screwed into the stem make it almost impossible to get the pipe cleaner past, due to the flat edge of the condenser [the part screwed up into the tenon airway] pointing away from the bowl.

Taking a clue from Mark’s Post #236 post on reducing turbulence by chamfering the tenon into a cone, using a drill bit, I have done the same thing to the flat end of the aluminum condenser.  Now my pipe cleaners just glide right on in.  But first, some theory.

What Mark has imprecisely called the “tenon extension” is  correctly understood as a “condenser.”  Yes, it does extend the tenon but that is not its primary purpose.  Over the last 130 years, many pipe makers have tried to incorporate something into their pipe to help control moisture and tongue bite.  Any scientist or engineer can report that one of the by-products of combustion (i.e. burning tobacco) is water.  It doesn’t matter how dry the tobacco is, burn it and you will get water.  How to manage it?

For every pipe maker there is a different design of a condenser.  Some are flat, some twisted, some are blades and some are tubes.  However, none of them understood the importance of a “system.”  No one except Charles Peterson.  What makes the Peterson pipe system different than all the others?


1. A moisture reservoir.  If there is going to be water and you don’t want to inhale or swallow it, what to do with it?  Make a miniature tank in the bottom of the pipe to hold it!  Genius.

2. A large (ish) condenser that minimizes flow disruption. Because of its tubular and gently curved shape, the Peterson condenser does not cause the flow to be disrupted. This allows for a smooth draw and maximizes contact of the smoke with the condenser.  This contact causes the moisture in the air/smoke stream to condense onto the aluminum and drip down into the reservoir.

3. A P-Lip with graduated bore airway. If you consider the tapered draw hole through the stem down to the condenser from approximately 1.5 to 5mm, Charles Peterson took advantage of Bernoulli’s principle with the P-Lip. By narrowing the draw tube, Peterson increased the velocity while lowering the pressure.  This means the smoker doesn’t have to pull as hard to get a good draw.

Over the last 50 years or so the use of condensers has fallen out of favor.  Most people who buy a pipe and find a condenser just take it out and discard it because it doesn’t work.  With nowhere to store the moisture, these condensers just build up nasty goo and block the air flow.  Furthermore, many condensers also block the draw hole, preventing it from being cleaned with a pipe cleaner.

Peterson still includes condensers in their DeLuxe, Premier and Pub System pipes, and they work.  The big deal is making sure they keep working, by keeping the pipe clean.

Every time a condenser-equipped pipe is smoked it should be cleaned.  Here is my method:

  1. Insert pipe cleaner into stem from the top or button end as far into the airway as it will go. Users of bent stem pipes will want to use Long’s Bristle Brush pipe cleaners (or equivalent) and may have to bend the end of the pipe cleaner slightly to get it started down the hole. If the pipe cleaner has gone into the condenser, push it on through and clean out the inside of the stem and condenser at the same time. No need to remove the condenser.  Set aside. Nine times out of ten the pipe cleaner will only go as far as the top end of the condenser and stop. We’ll deal with this issue in Step 4 and I’ll present a DIY solution to it in a moment.
  2. Next remove the stem from the shank and set the bowl aside. Make certain it stays upright.
  3. Using a tissue, wipe the outside of the condenser clean.
  4. If the pipe cleaner has stopped before going into the condenser (as it usually does), unscrew the condenser and use the tissue to clean the end of the stem. Run the pipe cleaner the rest of the way through the stem. Move it back and forth into the stem a few times.  One end of the pipe cleaner should be relatively clean.  Use it to clean the inside of the condenser.  Screw the condenser back into the stem and set aside.
  5. Taking the opposite corner of the tissue, roll it into a cone and twist it into the shank. Push as much tissue as possible into the shank. Use caution with this step, as the bowl still contains ash.
  6. Turn the bowl over your ashtray and tamp out the ash and any other residue. Hold the bowl upside down for at least a minute.
  7. Remove the tissue from the shank and inspect it. If it is moderately wet, you are finished. Put the stem back into the shank and return the pipe to its resting place.  If it is soaking wet, get another tissue and repeat this step.  It should never require more than two tissues to dry the reservoir.
  8. System pipes must be allowed to rest and dry out, so I recommend not smoking them more than once a day. Some sources say no more than once a week, but I have been using the daily rotation for several years with no problems. Once in a while I will put one of my regulars up for a couple of weeks to let it dry. You now have a scientific reason to buy more pipes!
  9. Every two or three years I get out the reamer to clean out and resize the bowls. Then the Kosher salt and alcohol to give the bowls a good cleaning. Finally, the Oxy-Clean soak overnight for the stems to remove the oxidation.  A good buffing and they are good to go.



As I noted at the end of Step 1, nine times out of ten the pipe cleaner will only go as far as the top end of the condenser and stop.  This is because the flat face of the condenser presents an obstacle to the pipe cleaner.

I have discovered that if I change the flat face into a [chamfered] concave taper or cone, the pipe cleaner goes in every time!  When I made my first modifications, I did it with a couple of drill bits.  First the smaller bit to get the cone started, then a large bit to keep it from going to deeply into the condenser.

This work is done by hand.  The aluminum is very soft and is easily cut by simply turning the bit in your hand.  Make sure you wear eye protection during this step.  A small piece of aluminum in the eye is serious business.

A piece of 400 grit sandpaper may be used to smooth the surface, if necessary. Here’s what the original condenser (left) and my first attempt at an improved version (right) look like:

First Modification to the Condenser

As you can see in the photo above, the OEM condenser on the left has a pronounced, flat “face” or top, whilst the modified condenser on the right does not.  This modification allows the pipe cleaner to enter smoothly when cleaning the pipe.

More recently I acquired a Mars-Rock burr set for my Dremel ($10 at Amazon) that has allowed me to make a much cleaner cut and surface to the modified face of the condenser:

Improved Modification With A Burr Drill Bit

As you can see, this is much cleaner as well as easier to control while making the modification.

I have smoked all of my condenser-equipped System pipes for a month without removing them for cleaning just to test what residue and moisture might be left behind when the condenser isn’t unscrewed to clean the stem’s mortise end.  I disassembled all of them and found only slight traces of gunk behind the convertor.  Another testimony to Peterson’s genius.



The squared-end tenon extension which appeared
c. 1937 and has been a feature of Standard System stems ever since

I could not always afford the DeLuxe system, so I have several Standard Systems I have been smoking for over 30 years.  They don’t have a condenser, and unlike the DeLuxe and Premier Systems, they do accumulate a lot of build up at the tenon of the stem, which requires that I use a folded pipe cleaner in cleaning them. [See Posts #154 and #208 for a history of K&P’s tenon extensions and condensers and Mark’s thoughts about them at that time.]

Mark: Aside from the conical extensions made from 1898 to c. 1945, there’s also less opportunity for moisture drip. The square-end tubular extensions (like the one seen in the illustration above) do give space for the moisture to circulate and drip down into the reservoir, but not with the efficiency of the bone or later aluminum condensers.

Stephen: Sometimes I wonder if Peterson intended all of his System pipes to use the condenser but somewhere along the line some bean-counter or efficiency expert came along and pointed out how much money could be saved by eliminating the condenser. On the other hand, it could have been feedback from customers, many of whom didn’t know or care about keeping their pipe clean and emptying the reservoir after every smoke and complaining that it got in the way.  I say this because I’ve met several people over the years who not only don’t clean their pipes regularly, they brag about the fact that they don’t clean their pipes! Then when their pipe gets so dirty or clogged it won’t work, it is simply discarded and replaced.  This approach may be fine for a basket pipe or a corn cob but I would never consider doing it with a Pete.

There’s another benefit to the condenser on the DeLuxe, Premier and Pub pipes that doesn’t get much attention: reduced turbulence or “drag.”  While reduced turbulence primarily means cooler smoke, it also means cleaner airways, witnessed by the fact that there is less time for gunk to condense and build up on the walls of the stem. This is a visible proof that the higher grade Systems smoke with less turbulence (i.e., cooler) than the Standard grades. The Standard grades, which lack the funneled condenser, accumulate more gunk at the tenon.



Gary: The first thing is to realize that as the pipe cleaner is inserted from the button, the flexural strength or bending of the cleaner in a bent System stem begins immediately:

1. When the cleaner enters the airway, it is formed into an arch


2. The arch of the pipe cleaner maintains the arc established by the smoke channel


When the arched pipe cleaner comes to the tenon end of the stem it will lodge on any protuberance. In the case of the System condenser, the block is the flat end or ledge, as Stephen has said.

3. Pipe cleaner blocked by the top wall or flat end of the condenser

This is why on any Standard System stem, incidentally, the pipe cleaner passes easily through from button to tenon.

First, an observation.  In all traditionally-made Systems stems, the airway was bored with a tapered drill bit—and this was the case throughout most of K&P’s history, although reports indicate this has not been the case with vulcanite stems of the past 10-15 years, and is definitely not the case with the acrylic P-Lips, which are “step” bored, that is, the first 10mm or so of the tenon end is drilled at 4-5 mm, then the airways goes down to 3.5 or 4mm for the rest of the channel (yes, this creates unnecessary turbulence, but is for some bean-counter or design fatigue reason easier than installing a tapered drill bit!

Second, the problem itself is revealed by the way the airway has been tapped or threaded. Most of us, when cleaning the tenon end of a high grade System, see this:

Drilled Tenon Hole Threads


What we don’t see is this:

Drilled Hole With Thread

What my drawing is attempting to show is that the tenon has been drilled or tapped to allow the condenser to screw into it. In almost every case, this means the threads extend beyond the end of the condenser for several millimeters. Result? The arched end of the pipe cleaner runs into either the threads and stops, or it runs into the flat top facing surface of the condenser and stops.

Note also that because the threads extend up into the airway, gunk is allowed to accumulate there. Turbulence is also created because of the ridges. Will the smoker notice the turbulence? Maybe not, maybe so, depending on the body chemistry, cadence and type of tobacco used.

The solution to the problem requires a hold drilled with a flat-bottom end mill cutter. Remember traditional drill bits are pointed, not squared off or flat. The flat-bottomed surface drilled by such a bit looks like this in magnification of a recent, factory-improved high-grade System:

Note the flat bottom inside the airway where the threads quit and the smoke channel becomes immediately narrower

If you look at the following diagram, you’ll see that the airway diameter is the same as it moves from the stem to the condenser. The only turbulence or drag, as well as gunk depository, now resides in whatever space is left between the end of the counter-bored hole and the beginning of the condenser, which will be considerably less than the conventional juncture between drilled tenon hole and condenser.

Counter bored Hole With Thread




Mark:  In the recent past (the last 18-24 months) I believe a change may have been made at the factory in the tapping (threading) of the condenser into the tenon of the stem. I don’t know whether this is intentionally the case or not, although I would welcome a comment by anyone at K&P or Laudisi who knows.  Here are four Laudisi-era stems, all of which pass the pipe cleaner from button to tenon:

Some fairly recent high-grade stems that pass a pipe cleaner through the condenser

The second from the top, you’ll notice, is acrylic. This one, unlike three vulcanite stems, accumulates more gunk above the condenser. As cleaning the pipe after smoking has always been a routine for me, this isn’t an irritation, just an observation.

I also want to remark, in concluding, that we should remember that engineering in a factory pipe and an artisan pipe is necessarily predicated on time and cost. We expect an artisan to devote considerable time and energy to airflow, turbulence issues, the button smoke channel and closing the tenon-mortise gap and we pay for those hours. What is remarkable to me is that in a factory setting the System usually matches and even surpasses the work of many artisans. Even the world’s finest artisan pipes will, if they have a bent stem, often require the pipeman to rotate the end of the pipe cleaner to get the tip to slightly turn and so enter the mortise.


Keep on Puffin!*


Stephen Wilson, CPG
Short background – US Navy, Electronics Tech, 6 yrs; College, BSEE, 3 yrs; worked as engineer, primarily in digital communications systems, 20 yrs; back to college, MSPM (project management), work as PM primarily on very large, technical infrastructure projects, 20 yrs; retired about three years ago.

Gary Hamilton, CPG
Gary has spent his working life outdoors as a geological engineer
in the petroleum industry, which has taken him to several continent
and some extreme weather. These days he prefers his shop, his ranch,
and wandering through antique malls in search of pipes to restore.







*Close readers of the Peterson book will recall there was an entry-grade pressed meerschaum line named Puffin. Totally unworthy of the noble bird, but certainly a great name that ought to be recycled at K&P, as Ireland hosts thousands and thousands of these wonderful little guys.

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