Phosphate layers formed in a model bath were electrochemically modified with copper and a cataphoretic polymer film. While Cu fills the total pore volume, the deposition of the polymer is, in the initial phase, restricted to the bottom of the pore. This behaviour was used to determine the effective layer thickness and the pore volume. A cone shaped opening of the pores is concluded from transients of copper deposition and in connection with the cataphoretic painting experiments. These results matched the growth mechanism of the phosphate layer suggested in our previous studies.