Automatic Document Feed, or ADF, is defined in this paper as the ability to feed printed matter in large amounts through the paper-handling equipment of copiers. The desire to perform this operation on any kind of printer output without annoying interruptions or jams is widespread among customers. This is particularly true for prints from color printers. Until now it could be reliably achieved only by prints from xerographic and ink jet color printers. The output from solid-ink color printers on the other hand - despite excelling in many areas - was not competitive in this point. The reason for this has to be seen in a high Coefficient of Friction (COF) of ink-covered parts of documents against the glass surfaces present in the imaging systems of copiers.Great efforts have been made, and several solutions were proposed, to find a remedy for this problem. In this context, it is an important task to measure the progress in product performance. Clearly, the Coefficient of Friction under the above mentioned conditions fulfills this demand from the point of view of the engineer or physicist. But how can this easy to determine number be translated into meaningful information about the most likely performance in the field? To find an answer to this question, this paper addresses the problem of setting control limits for the Coefficient of Friction of solid-ink color prints, introduces the “ADF-Index” for measurement of customer satisfaction, and attempts to give a correlation between COF and ADF-Index.