The amount of residual sugar left in the wine will vary from 50 to 125 g/l (5 to 12.5% RS). Prior to fermentation, the grapes destined for Maury production (predominantly Grenache) are harvested very ripe usually with a potential alcohol level (based on the amount of grape sugar alone) at 14.5% (around 25 to 27°Bx or 13.8 to 15 Baumé). After crushing, the must usually undergoes a period of extended maceration that can last up to 30 days. During this time the cap of grapes skins is frequently punched down ("pigeage") or the juice pulled out from under the tank and pumped over the cap to allow for a more thorough extraction of phenolics that influence tannin, colour and aroma. Usually during this maceration, the fermentation process starts with ambient yeasts in the cellar. Often the wine will have fermented to the point where the grape spirits are added before maceration has ended and the wine is pressed off the skins, a process known as "mutage sur grains". The added alcohol during maceration allows for more ethanol-soluble phenolics and flavor compounds to be extracted. After pressing, the wine is left to settle in concrete vats over the winter before it is racked into barrels or other containers. Since the fermentation process is halted rather quickly, the flavors of Maury do retain some of the natural primary grape aromas of Grenache along with some of the early fermentation esters that develop. But most of the distinctive character of Maury come from the aging process that can take place in a wide range of containers (from concrete and oak barrels to glass "bonbonnes") kept in a variety of conditions (including out in the sun for deliberate oxidation) for a number of years depending the particular house style of the winemaker. One style of Maury known as "rancio" is produced when the wine is racked into clear glass demi-johns or "bonbonne" and left out in the summer sun to oxidize and age. This causes many of the colour compounds and tannins in the wines to fall out, leaving a thick, dark coloured deposit in the "bonbonne". This deposit is allowed to stay in the "bonbonne" to influence the colour and flavour of resulting vintages of wine that are aged in the container. Once the wine has finished aging for the summer it is usually blended with wine that has spent time aging in large "foudres" oak cask or sold separately as "Maury Rancio".