Checking the oBrix Reading of Our Grapes

Now that we have grapes my husband purchased a refractometer for us to use to check the ^oBrix reading of our grapes. The Wine Spectator Glossary defines ^oBrix as the following:
^oBrix: A measurement of the sugar content of grapes, must and wine, indicating the degree of the grapes' ripeness (meaning sugar level) at harvest. Most table-wine grapes are harvested at between 21 and 25 Brix. To get an alcohol conversion level, multiply the stated Brix by .55.
^oBrix is actually a summation of the amount of sucrose, fructose, vitamins, minerals, amino acids, proteins, hormones, and other solids in the juice.
^oBrix is the scale most often used to measure sugars in winemaking: 1^oBrix = 1% sugar (wt/vol), or 1 gram sugar in 100 mL.
In oder to measure ^oBrix, we purchased a device known as a refractometer. We bought ours from the Valley Vintner. Our kit came with the refractometer which is temperature compensated (Automated temperature compensation ATC), a small vial of distilled water, a screw driver for adjusting the baseline, a plastic "eye" dropper as well as a cloth. There also was a set of instructions on the care and use of the refractometer.

The hand held refractometer is a handy device because it can measure the ^oBrix of a small sample. We don't have too many bunches of grapes so we cannot do the statistical analysis that is required to get an accurate measure of the entire collection of Auxerrois and Chenin Blanc grapes, so we have been taking tests using one grape at a time. This is fun!
Our Auxerrois is ahead of our Chenin Blanc with ^oBrix measuring between 14-16 and the Chenin Blanc is currently between 10-16. The Chenin Blanc is much more variable since we also have some very green clusters that have not reached véraison and the ^oBrix is at 5.0.