A process of manufacturing an aldimine preparation, characterized in that at least one aldimine of the formula (I), at least one isocyanate of the formula (II), optionally at least one alcohol of the formula (III) and water are reacted until at least 95% of all the initially present isocyanate groups are converted, whereby the initial molar ratio of aldimine groups to [isocyanate groups minus hydroxyl groups of the alcohol of formula (III)] in the reaction mixture is in the range of 2/1 to 10/1. The obtained aldimine preparation is particularly suitable for the use as latent hardener for moisture-curing polyurethane compositions. It enables moisture-curing polyurethane compositions with a very low content of diisocyanate monomers, which cure to an elastic material of surprisingly high strength, e-modulus and low surface tack.