In Robertson v. Norton Co., plaintiff brought breach-of-warranty and strict liability claims against the manufacturer and the distributer of a ceramic-composite grinding wheel on a heavy-duty power sander/grinder. 148 F.3d at 905–06. At trial, plaintiff’s ceramics expert testified that the manufacturer’s warnings were “‘completely inadequate’ because the warning label did not explain ‘improper use,’ a copy of the safety guide was not enclosed with each grinding wheel, and the warning label’s cross references were ineffective.” Id. at 907. The Eighth Circuit held that the trial court abused its discretion by allowing the ceramics expert to testify on warnings because he was not qualified to do so. Id. “He had never designed a warning for