By the early 2nd century A.D., the entrepreneurs of the glassworking industry most likely were the descendents, three or four generations removed, of the slaves who in Republican and Augustan times had been treated simply as household chattels. Changes in shape and decoration of Roman glassware generally were quite conservative, with only minor modifications of glassware's mid-to-late 1st century A.D. aspects, rather than sharp departures from them. Perhaps this was the result of a reasonable caution on the part of new workshop owners who, if we are right in identifying their slave origins, had improved their lot amid formidable social barriers. Or the conservatism may reflect the fact that glassworking was not being infused by much fresh blood at this time: rather, it was based on father-to-son training and inheritance.
During the 2nd century A.D. the shape of free-blown unguentaria evolved gradually in two directions that modified the body's shape from a flare-mouthed bell to either a wide-mouthed cone or a squat discoid. The base was now often concave, becoming more exaggerated in that sense as time went on. The neck became far more extended, presumably to slow evaporation of the contents.