ArticleCalibrate your Winemaking ToolsWritten by Chris ColbyYour hydrometer shows that your must has a specific gravity of 1.100 - but how do you know that's accurate? Learn how to calibrate your hydrometer and all your winemaking tools, so you can be sure.Already a member? Log InYou'll Also Like Article FREE Choosing Your First Fermenter Explore the options for your first fermentation vessel. Article MEMBERS ONLY Moving Wine with Pumps Wine is frequently transferred or “racked” into another vessel to leave the byproducts of the process (known as lees) behind. If you make larger batches of wine at home, using a pump can make this process easier.