A bartender often has to quickly pour liquid, e.g., wine or other drinks, into glasses while trying to pour a desired amount of liquid into each glass. One method of pouring a desired amount of liquid into a glass is for the bartender to first pour the liquid into a measuring glass to get the desired amount of liquid, and then pour the desired amount of liquid from the measuring glass into the glass. A problem with this method is that it takes time to first pour the liquid into the measuring glass and it may be difficult to read the measurement mark on the measuring glass, especially if the mark is not viewed at eye level.
There are liquid pouring spouts for liquor, but they generally only measure 1.5 to 2.5 ounces, which is generally not enough for wine.
At restaurants and parties, a server often has to pour wine from a bottle into several glasses. A problem is that it is difficult for the server to pour the same amount of wine into each glass. The server often has to pour the wine into the glasses, visually inspect the amounts of wine in the glasses, and pour some more wine into glasses that have less wine. This process of pouring and re-pouring wine to make sure that the glasses have the same amount of wine can be time consuming.