Pattern formation from a silica colloidal suspension that is evaporating has been studied when a movement is imposed to the contact line. This article focuses on the stick-slip regime observed for very low contact line velocities. A capillary rise experiment has been specially designed for the observation and allows us to measure the pinning force that increases during the pinning of the contact line on the growing deposit. We report systematic measurements of this pinning force and derive scaling laws when the velocity of the contact line, the colloid concentration, and the evaporation rate are varied. Our analysis supports the idea that the pinning of the contact line results from a competition between the geometry of the growing deposit and the force due to gravity.