A sugar solution of a known concentration is useful for testing the accuracy of a brix refractometer. This device measures the concentration of sugar in a solution and is frequently used by winemakers. By calculating the accuracy of the brix refractometer, you can determine the correction factor to apply to its measurements. This correction factor is necessary because winemakers typically prefer accuracy to the nearest tenth of a percent.

1 Select a scale. This scale will need three digits of accuracy if possible, so a scale that weighs in grams will need to be accurate to the nearest tenth of a gram. The scale will also need to be adjustable so that you can "zero out" the scale before each measurement.

2 Zero out the scale and place the empty water container on it. This will be the container that you mix the sugar solution in. Record the weight of the empty container.

3 Fill the container from Step 2 with the desired amount of distilled water. This should be enough water to fill the test container for the brix refractometer, typically 100 milliliters (ml). Zero out the scale if needed and weigh the filled container. Subtract this weight from the weight of the empty container to determine the weight of the water.

4 Calculate the amount of sugar to add to the water to achieve a solution of the desired concentration. This is given by the equation s = pw/(100-p), where s is the amount of sugar to add, p is the desired percentage of the sugar solution and w is the weight of the water.

5 Zero out the scale and weigh the empty container that you'll put the sugar in. Add this value to the amount of sugar you calculated in Step 4 and record the desired total weight of the container and the sugar. Carefully add sugar to this container until the scale shows the desired weight. Add this sugar to the water you weighed in Step 3 and stir until the sugar is thoroughly dissolved.