The invention relates to a method of making a laminated substrate for use in an immunodiagnostic device and a machine or apparatus for marking the substrate with reagent. The method of forming the laminated substrate creates a rollable chromatographic medium. The chromatographic medium can be biphasic or multiphasic. The biphasic chromatographic medium comprises a capture medium precast onto a plastic backing and a release medium. The release and capture media are bonded to a liner material such as a plastic film. The multiphasic chromatographic medium comprises a capture medium precast onto a plastic backing, a release medium, and a sample absorbent medium. The capture medium, the release medium and the sample absorbent medium are disposed on a liner material such as a plastic film. The biphasic and multiphasic laminates are prepared for use as immunoassays by a specially adapted machine or apparatus. The machine includes a leader, an unwind system, a reagent dispensing system, a substrate reject marking system, a drying system, and a rewind system. In one exemplary embodiment, the machine applies four reagents to the substrate. The particular reagents used in the machine will vary depending upon the immunoassay to be performed.