Detectable marks in trim material

The manufacture of absorbent articles such as diapers, training pants, incontinence underwear articles, and the like, typically includes compiling and processing a web substrate as a continuous band of end-to-end or side-to-side work pieces from which respective absorbent articles are eventually derived, typically one absorbent article from each work piece. The compiling and processing includes assembling various elements to the web substrate, and shaping and configuring the thus assembled composite web substrate. This invention pertains to methods of checking for successful removal of trim material from trim areas disposed at periodic intervals along a web in a processing line. Marking material is marked, optionally as reference marks or reference images on the trim material pieces. Trim material is severed and removed to develop cut-outs at the trim areas. After removing the trim material, the method senses for the marking material at and adjacent the trim areas. The method thus detects marking material on trim material pieces which are not successfully removed from the web. In preferred embodiments, the web, outside the trim areas, is free from the specific marking material used for the reference marks or reference images. The marking material is preferably detectable, using a suitable sensor, independently of visible light emanating from, or reflected from, the marking material. Exemplary marking material can be detected using magnetic flux, energy in the ultraviolet spectrum, an olfactory sensor, color discrimination, energy in the infrared spectrum, and/or an optical brightener detectable through action of energy in the ultraviolet spectrum. The invention comprehends a web comprising corresponding trim areas, corresponding trim material, and corresponding marking material.