We have a big decorative urn full of coins in the upstairs hallway, because nobody likes to carry coins, so they get tossed in there. It weighs about 50 pounds, but most of those coins were contributed years ago, because we use debit cards now for everything. I rarely carry cash and don't think I've had a coin in my pocket in years.
I mention coins because I've always heard that the proper thickness for cake in the bowl of a pipe should be about that of a dime or a nickel, and I want to talk about cake, but does anyone even use dimes anymore? So many things have become obsolete that I'm not entirely confident everyone is any more familiar with coins than with VHS players or rotary telephones. Many may have a historical interest in such things as dimes, but are they still objects useful as units of physical measurement?
Anyway, if you're unfamiliar with dimes, the cake in a pipe should be maintained at about the thickness of one or two debit cards. Cake is the carbon buildup on the walls of the tobacco chamber. Its gradual thickening is a relatively slow process, though it can creep up on you. When I started smoking pipes, it seemed like it took forever for cake to build, but now I'm mildly irritated every time I see it's time to ream a pipe yet again. It also used to feel like a bowl of tobacco lasted much longer than it does now, but I don't know if that's because time is accelerating or my impatience is decreasing. However, even when the perception of time has changed, the need for keeping cake at the proper thickness has not.
Cake is the carbon buildup on the walls of the tobacco chamber. Its gradual thickening is a relatively slow process, though it can creep up on you.
Cake helps insulate and protect the briar of a pipe, but if it gets too thick, it may have adverse effects. You've probably seen pipes in antique stores or flea markets that have too much cake. The remaining tobacco chamber can sometimes be little more than the diameter of a pencil, and I'm not sure how the owners managed to enjoy smoking them in that condition. Pipes afflicted with excess cake such as that are often cracked, and that is perhaps the best indicator that cake should be well managed.
While cake is necessary for the good health of a briar pipe, like anything, too much can be a bad thing. Cake expands and contracts with heat and cooling at a different rate from briar, and when it expands it can crack the bowl. Briar is very tough, but it can't withstand repeated forced expansion and contraction at the level that is forced on it by excess cake.
However, removing cake the right way requires tools. Our grandfathers used pocket knives, and they work, but a sharp-tipped pocket knife risks damaging the walls of the tobacco chamber. A gouge in the briar where combustion happens can lead to char around that gouge and the potential for further damage. So blunt instruments are safer.
Better than a regular pocket knife is a pipe knife like the Brigham, John Aylesbury or Joseph Rodgers, all of which have blunt rather than sharp tips, and blades that are less sharp than that of a pocket knife. They have the advantage of being able to reach into the bottom of most tobacco chambers, though that part of a chamber seldom requires reaming — unless the pipe is oversmoked at the heel, which in itself risks damage.
The area around the smoke hole is one of the most delicate parts of a pipe, particularly in terms of excess heat applied as a smoker reaches the end of a bowl of tobacco. Because tobacco at the bottom of a bowl tends to absorb the moisture resulting from combustion from the upper layers of tobacco, more heat is necessary to keep it burning, and protective cake builds very slowly at the heel, if at all. I've had the advantage of seeing lots of used pipes, and most have cake built in the upper two-thirds of the bowl, with little cake at the heel. That inconsistency also contributes to the danger that cake imposes on a pipe. Thinner cake throughout reduces that inconsistency. As you may imagine, thick cake expanding with heat up top, while the lower section of the bowl does not expand, can cause lots of stress on the briar.
There is no perfect tool for cake removal, however, and with a pipe knife it's difficult to maintain consistent thickness of cake, though with practice and a steady hand it's possible. For ease of use, however, other tools are available, like the Brigham Pipe Reamer and the Neerup Chamber Reamer, both of which have blades on two sides and provide more consistency. The Brigham has the advantage of being adjustable, however, which is necessary, as any collection of pipes will tend to have chambers of differing widths.
Removing cake the right way requires tools. Our grandfathers used pocket knives, and they work, but a sharp-tipped pocket knife risks damaging the walls of the tobacco chamber.
It's best to ream a pipe gradually, rather than aggressively, so adjustability is a benefit in multi-bladed reamers. If cake is over-thick and you immediately apply a reamer that will reduce it to its final best thickness, there's a good possibility that you'll tear chunks from the cake and leave an uneven surface, allowing more heat to reach the briar at the cake's low spots. I personally most often use the Pipnet Pipe Reamer system, which provides four different widths of reamer: 17 mm, 19 mm, 21 mm, and 23 mm, each with four blades. Unfortunately, it's hard to find and is almost always out of stock, which may tell you how popular it is. Depending on the width of the bowl and thickness of the cake, I start small and work my way up.
It isn't perfect, though. One downside is the sound of reaming generated by the Pipnet, which is worse than fingernails on a chalkboard, and much, much louder. Colleagues unfamiliar with that sound have heard it coming from my office and been alarmed that I was throttling baby birds, though none have had the courage to check. They've probably thought it best not to know. To be fair, piercing sounds often emerge from my office, usually in the form of loud, Tourette's-like exclamations of profanity, growling, and the occasional breaking of furniture, all generated by the frustration of being unable to find the right word or sentence structure as I work, and my co-workers have learned that it's in their best interests not to interrupt. Throttling baby birds is the least worrisome of their speculations, and for safety's sake and at the behest of our HR department, they do not approach.
But even with the disadvantage of the concurrent ear-piercing screech of reaming with a Pipenet, I find it the easiest and fastest method, though it too can tear chunks from the cake and leave an uneven surface, no matter how gradually and carefully I try to work. I've also found that it's difficult to keep the smoke hole centered in the cake, and I often drift to the side and risk hitting raw briar. I don't know about you, but I find that cake bulls faster on the near side of the chamber over the smoke hole, perhaps because of the airflow that accompanies the necessary engineering of pipes, with the exception of Calabashes, which have smoke holes centered in the bottom of the chamber. It's difficult with a Pipnet to exert more pressure on one side than another to more aggressively reduce cake where it's uneven.
Perhaps the most historically popular reamer is the Senior Pipe Reamer, which is also almost always out of stock. (Our site has an option, however, on all out-of-stock items for an email notification when the item is again available). The advantage of the Senior Reamer is its infinite adjustability. A turn of the knob at the end gradually expands the four double-sided blades to whatever width you're currently needing. It also has an internally housed, manual drill bit for clearing the shank, which is convenient, but only on rare occasions, in my experience. I own a Senior Reamer, but more often use the Pipenet because it's easier and faster.
Neither the Senior Reamer nor the Pipnet is able to reach the bottom of V-shaped chambers, so you'll need a blunt-tipped pipe knife to clean up any flakes of tobacco that have become lodged in the minimal cake at the heel. Always be especially careful around the smoke hole and try to maintain its original condition as best you can. Any carving away at the smoke hole, either from charring or over-reaming, can change the pipe's smoking characteristics and leave it more susceptible to further damage.
It's best to ream a pipe gradually, rather than aggressively, so adjustability is a benefit in multi-bladed reamers.
There's only one way I know of for near-perfect reaming, but it's labor-intensive and very messy: Sandpaper. Wrap some 400- or 600-grit sandpaper around a wooden dowel of appropriate diameter, and sand the cake around the sides. Sandpaper is less likely to tear chunks from the cake, and is easier for re-orienting a chamber to the center of the bowl with consistent cake width around the sides. It doesn't reach to the bottom any better than the other tools mentioned here, but as stated, the bottom of the chamber rarely needs any reaming, and just a few swipes of folded sandpaper can easily clear any protrusions at the heel.
But again, be very careful around the smoke hole. Wrapping the sandpaper around a finger provides tactile feedback that is superior to a dowel, but a dowel will provide more consistency. You may want to perform the task in a bathtub, though, as the fine carbon resulting from sanding cake will get everywhere. It's messy no matter what tools you use. At the least, spread out newspapers on your work surface and have some rags or paper towels at the ready, and be prepared for cleanup. It will get under your fingernails, it will darken the creases in your hands, and in my case, it almost always makes it onto my face and into my hair. But reaming is essential, and it's one of the necessary rituals of pipe smoking.