Tobacco Casings and Top Dressings

(Russ Ouellette) Most pipe smokers are familiar with the terms "casing" and "top dressing", but what are they, how are they used and how are they different from each other?
First, contrary to legend, most tobaccos that contain Virginia and/or Burley (which is the vast majority of blends) are cased, including some that refer to themselves as "unflavored". This, in essence, can still be true as some casings are as simple as sugared water. Casings are mostly used to lessen the negative qualities of a tobacco.
If a Burley has a high pH which can lead to tongue bite, a casing (with or without a flavor) containing some sugar will help to bring the smoke back toward the acidic side, and will reduce the chance of bite. Some Virginias can be harsh or ashy, but with the right casing, that can be mitigated as well. Mostly, though, casings are not used to flavor the tobacco as much as to prepare it for other processing, much as a mild marinade is used to prepare meat for cooking and to tenderize it more than to flavor it. Continued