Bottoming: prep substance, not the bottom

To most people, bottoming is a verb: hitting the bottom, reaching the lowest point, or forming a foundation. A car bottoms out. Unemployment bottoms out. A ship's hull forms the bottom. The word suggests arrival at an endpoint or base layer.

In textile production, bottoming is a noun: a sizing or mordant substance applied to a fabric to prepare it for dyeing. The bottoming treatment opens the fibre structure, improves dye uptake, and ensures even colour. It may contain starch, gum, or chemical mordants. The fabric is impregnated with bottoming, dried, and then passed to the dye bath, where it will take colour more uniformly and hold it more reliably than untreated material would.

The two senses share a metaphorical ground. In general use, a bottom is a foundation; in textile chemistry, bottoming is a foundational treatment. The word moved from describing location to describing sequence or preparation. What comes first, at the bottom of the process, supports what comes next.

The textile sense is now historical or regional. Modern industrial dyeing uses the term less often, preferring names of specific chemicals or processes. But the logic persists: before a fabric can accept colour well, it must be prepared with a preliminary substance. That substance was, and occasionally still is, called a bottoming.