Since the word "etch" is mentioned, my guess is that the team was performing some kind of IC fabrication process (or some thing similar), possibly involving Rea

Since the word "etch" is mentioned, my guess is that the team was performing some kind of IC fabrication process (or some thing similar), possibly involving Reactive Ion Etching. In this regard, I can understand the frustration. The etching process itself may take up a lot of time. Not to mention the pattern on top of the substrate may require several stages to be established before etching, costing time (hours to days) and money (we are talking about photoresist, metal like gold etc, and other non-metal coatings). One step gone wrong then you have to throw everything in the bin and start over. Since the etching time cannot be controlled in this batch (from 5 mins to 30 mins), this may suggests that the "ITO glasses" are not the same. And since there is no way to tell, the logical approach is not to bother with the remaining samples and simply ask for the new batch.