Sandblasting: Circles and Shanks

Circles and shanks in sandblasting covers two dimensional effects commonly seen on deeply blasted briar pipes together: the bowl not reading as a perfect circle from above, and the shank ending up thinner than the mouthpiece it joins. Neither comes from careless finishing; both arise from the abrasive removing material from the wood. The workshop side of the subject is laid out comprehensively in an article published in April 2008 under the byline of maker Trever Talbert.

The Abrasive Doesn't Only Take From the Surface

Sandblasting's operating principle is that briar's soft early wood wears faster than its hard late wood. A light application removes only the top layer; the stummel largely holds the line it came off the lathe and sandpaper with. As pressure and duration increase, the abrasive digs deeply into the soft zones, leaving behind a skeleton formed by the hard zones. Every layer removed is also a share subtracted from the dimensions: the outside diameter of a deeply sandblasted bowl drops below its pre-blast measurement. That's why a maker aiming for deep texture leaves the stummel somewhat oversized to begin with, reaching the finished dimension only after blasting. Uncontrolled pressure causing shape distortion in briar is a shared warning across technical accounts.

Where the Shank Meets the Mouthpiece

Dimensional loss shows up most on the shank. The bowl is judged on its own; the shank, though, has to match the mouthpiece in both thickness and line. A shank blasted at the same intensity as the bowl thins out, and a visible step forms at the join. Three approaches are on record for this point:

• Gradually lowering the pressure from bowl to mouthpiece. The end of the shank near the bowl is left thick and blasted deeply; as it nears the mouthpiece, pressure drops, giving a single continuous line top and bottom.

• Wrapping masking tape around the area where the mouthpiece seats. That spot stays smooth briar while the rest of the shank is lightly blasted.

• Leaving the shank thick to begin with and blasting it at the same intensity as the bowl. In this path it becomes harder to keep the join surface flat, and the wood's hard zones can protrude past the line of the mouthpiece.

A shank noticeably thinner than the mouthpiece isn't a problem for collectors who want blast depth uniform across the whole pipe; for those who care about a continuous line, it's a flaw. When a worn look is the goal, this step is sometimes left in deliberately.

Departure From a Circle at the Bowl

On the bowl side, dimensional loss also changes the shape of the cross-section. Since the grain structure isn't identical on the two sides of the stummel, wear isn't even; viewed from above, what one sees isn't a circle but an irregular line traced by the hard zones. Judging a pipe as "unevenly blasted on the two sides" is therefore often misleading; what's uneven isn't the pressure but the wood itself. Seeing the distinction requires learning to read a sandblasted surface.

Two ways of preserving deep texture while bringing the outer line closer to a circle are known. The first is to work with very fine nozzles and direct the abrasive in pinpoint fashion: pits open up while the overall shape stays intact, though very few makers can pull this off. Modern accounts of this kind of work describe nozzle openings selected at the scale of a thousandth of an inch, with very fine glass beads used as the abrasive. The second, more common route is a two-stage process: the stummel is blasted deep first, the outer surface is brought closer to round with sandpaper, then a light pass is made over it once more. The deep pits stay in place while the whole surface retains its sandblasted texture look.

Both points show that sandblasting isn't a surface finish tacked onto a finished pipe afterward; it's a decision made before the stummel's dimensions are even set.