  In this paper we compute detailed evolutionary models providing chemical
profiles for white dwarfs having progenitors in the mass range from 1.0 to $7
M_{\sun}$ and we examine the influence of such profiles in the cooling process.
The influence of the process of separation of carbon and oxygen during
crystallization is decreased as a consequence of the initial stratification,
but it is still important and cannot be neglected. As an example, the best fit
to the luminosity functions of Liebert et al. (1988) and Oswalt et al. (1996)
gives and age of the disk of 9.3 and 11.0 Gyr, respectively, when this effect
is taken into account, and only 8.3 and 10.0 Gyrs when it is neglected.
