摘要 |
<p>Detecting silica as a pigment-containing ink jet coating, comprises feeding a recording material with at least one ink jet coating that is applied on one side of the recording material, where the ink jet coating contains silica as a pigment, applying a test tincture on the ink jet coating, and determining an existing permanent color reaction of the test tincture with the silica. An independent claim is included for the test tincture for the detection of silica, comprising bromocresol purple, optionally phenol-red, which is phenolsulfonphthalein, and optionally polyethylene glycol.</p> |