Protruding yarns from the fabric are an important indicator of yarn interaction within the fabric and a predictor of fabric surface properties. Factors affecting protruding yarns govern either the structural or mechanical properties of yarn. An analytical model for plain weave fabrics describes the fundamental factors affecting fabric surface protrusion. Experimental data validated the model for normal loads and yarn spacing. Part II will examine the elastic modulus and the moment of inertia of the cross section of the yarn. 10 refs.