I am now reviewing the results of measurement tests I completed on Tuesday. The refractometer arrived on Monday in perfect order. I had to wait a day until I had some time to do things properly. I had a fresh set of Brix standards produced in advance. “Water zero” was measured against distilled water we receive from a service that handles bottled water. The reading was 0.00 degrees Brix. No adjustment was necessary. The standards were 10, 15, 20, 25, 30, and 67.5 degrees Brix. Readings were not farther away from the nominal values than +|- 0.02 degrees Brix. These results track with the uncertainty of the balance used in the production of the Brix standards. I do not use “RO water” from our laboratory’s water filtration system as a “water zero” standard. I will make clear in SOP training that only distilled water is to be used. Our laboratory manager was saying that RO water is OK to use, but I have noted from measuring these waters that only distilled water re-quires no adjustment from the factory setting. I may revise the SOP to emphasize the need to use distilled water. Folks in our lab do not understand the potential importance of this topic because they measure unknown Brix values of grape juice. I measure the known Brix values of prepared standards together with conservative estimates of uncertainty. I do not see how I could be happier with the refractometer. To finally have a serious instrument at my disposal is a dream come true. To have things go wrong with a new instrument of considerable complexity without prior experience is not a good feeling. Surely, there must be something I might be doing incorrectly. I went over my steps many times before I called; sure glad I did. I am holding on to all of the reference materials that were thoughtfully included with the refractometer. I wish to thank the many people at Rudolph who helped me through this matter. It can be difﬁcult trying to help somebody at long distance with technical gear worrying about production deadlines. Sharing your mobile telephone number really helped. – My goal is always to learn; please advise me at any time I am doing something wrong or am unclear on a concept.