When a fiber is brought into contact with a soft etching liquid, a conical tip is generally shaped. We show here that the use of corrosive liquids which release gases during the etching reaction may lead to original self-similar shapes, because of successive pinning and detachment of the meniscus. The conditions for the formation of this shape and its evolution are described. In particular, we stress the effect of convection due to released bubbles. (C) 2003 Elsevier Inc. All rights reserved.