The Muscadelle juice is fermented until it reaches the desired sugar level of between 14° or 17° baume, at which time the fermentation is cut short by the addition of grape spirit, which kills the yeast and lifts the total alcohol of the Muscadelle to about 18%. The grape spirit used is 95-96% SVR or Spiritus Vinum Rectificatum which is distilled from grape product. Following fermentation, the new wines are placed in old oak casks of various sizes, to allow the flavours of the Muscadelle to integrate and mature, but without the overt influence of new oak. The placement of barrels can influence the speed of a wine's development, with wines from barrels at the top of a stack nearer the winery's roof where it is hotter maturing faster than wine from barrels at the bottom nearer the cooler floor area. Evaporation plays an all-important role in the Muscats of Rutherglen. On average the maturing casks of Muscadelle lose 5% of their volume each year to the sun. This makes the production of Rutherglen Muscat a costly business, but without this concentration of the Muscat through evaporation these would not be the world's richest wines. The real art of the Rutherglen Muscat makers is their extraordinary ability to assemble parcels of Muscat from a range of wines of varying vintage, richness and complexity, to consistently blend each of their products year after year. Chambers achieve this process through a solera system where each of the Muscat products is drawn down through a series of barrels into which selected parcels of new vintage Muscat or a range of matured wines have been added from time to time. This creates a master blend that maintains the consistency of each finished product for final bottling.