Results of scratch testing on hybrid organic-inorganic coatings on float glass are reported. The effects of the preparation conditions on the apparent scratch resistance are tested using a sphere. As parameters to quantify the scratch resistance the load and the area of delamination as well as the length and number of surface cracks are considered. It is concluded that the main reason for delamination is the deflection of cracks at the interface. A model is proposed to estimate the distance between cracks. (C) 2001 Elsevier Science B.V. All rights reserved.