  We performed high-resolution simulations of two stellar collisions relevant
for stars in globular clusters. We considered one head-on collision and one
off-axis collision between two 0.6 M_sun main sequence stars. We show that a
resolution of about 100 000 particles is sufficient for most studies of the
structure and evolution of blue stragglers. We demonstrate conclusively that
collision products between main-sequence stars in globular clusters do not have
surface convection zones larger than 0.004 M_sun after the collision, nor do
they develop convection zones during the `pre-main-sequence' thermal relaxation
phase of their post-collision evolution. Therefore, any mechanism which
requires a surface convection zone (i.e. chemical mixing or angular momentum
loss via a magnetic wind) cannot operate in these stars. We show that no disk
of material surrounding the collision product is produced in off-axis
collisions. The lack of both a convection zone and a disk proves a continuing
problem for the angular momentum evolution of blue stragglers in globular
clusters.
