What is the pipe cleaner test and how important is it?
The so-called "pipe cleaner test" is a simple way to check the alignment and drilling precision of the draft hole on a pipe. The test is performed by attempting to insert a standard pipe cleaner from the bit end of the stem all the way through the shank and into the tobacco chamber. On a well-drilled pipe, the pipe cleaner should pass easily with minimal resistance.
The idea behind the test is simple: since the free movement of air (and smoke) through the draft hole is a key factor in how well a pipe smokes, if the pipe cleaner passes smoothly through the stem, shank, and into the bowl, it can be a good indication that the particular pipe will smoke well. For this reason, many folks swear by this test as a way to evaluate new pipes or a starter pipe they are considering for purchase.
Although a well-drilled draft hole is certainly important, it is not the only factor that affects the smoking qualities of a pipe. Therefore, even though the pipe cleaner test is helpful, it does not always provide an accurate assessment of how well a pipe may smoke.
Sometimes the design of a pipe may make it difficult to pass a pipe cleaner from bit to bowl, even if the draft hole is drilled accurately. This is especially true with uniquely shaped pipes or those that have a high degree of bend in the shank and stem, such as Oom Paul shaped pipes.
On the other hand, some pipes that do pass the pipe cleaner test may present other problems during a smoke that are not related to the draft hole. For example, a pipe with excessively thin walls on the bowl may cause the pipe to burn too hot during the smoke.
Other factors, such as whether or not the pipe has a special enlarged chamber for accepting filters, can also influence the usefulness of the pipe cleaner test.
I have numerous pipes in my own collection that cannot pass the pipe cleaner test, yet they smoke amazingly well. By the same token, I have several that can pass the test and do not smoke as well as others can.
As with many things, a little common sense will go a long way here. The pipe cleaner test can be a useful way of evaluating the craftsmanship of a pipe, but it should not be "ultimate authority" in your choice of pipes.