A slender-jet model for the pinching of a liquid column is considered in th
e limit of vanishing viscosity. We find the model to develop a singularity
in the gradients of the local radius and the velocity at a finite thread ra
dius, so it does not describe breakup. However, the observed steepening of
the pro le corresponds to experiments and simulations with fluids at low vi
scosity. The singularity has a self-similar form, which we compute analytic
ally. The result agrees well with numerical simulations of the model equati
ons.