yeast over time, but nowadays various fining agents are used to hasten the process as well. Kilju can be refined into pontikka (Finnish moonshine) by means of distillation. It then resembles rum, as both are distilled from fermented cane sugar products, although rum is often made from molasses, a byproduct of the sugar refining process, or fresh sugar cane juice instead of refined, crystallized table sugar. Rum thus has a discernible taste of its own, whereas pontikka distilled from (well-clarified) kilju more resembles diluted neutral spirit, vodka, or viina. Kilju is often produced improperly by home brewers who allow contaminants to disrupt fermentation or do not adequately filter or rack the liquid, or do not use a fining agent. The latter mistakes result in yeast being suspended, causing the mixture to be cloudy rather than clear. The yeast is not harmful, but can yield an unpleasant taste and intestinal discomfort. It is also a common mistake to leave the carbon dioxide produced by fermentation into the suspension, so that the yeast provides it with nucleation sites, keeping the yeast up in the solution. Proper technique calls for airing the product after fermentation, stirring, and perhaps for fining agents such as microsilica or various semipolar proteinaceacous or carbohydrate agents. When homebrewing grew in popularity during the economic depression that followed the Finnish banking crisis of the early 1990s, yeast strains known as "turbo yeast" ("turbohiiva", "pikahiiva") were introduced to the market. These yeast strains enable a very rapid fermentation to full cask strength, in some cases in as little as three days (compared to several weeks required by traditional wine yeast strains). Such a short production time naturally does not allow the yeast to become lees. The introduction of turbo yeast reinforced the public's view of kilju as an easy method of procuring cheap alcohol. Kilju is a well-established part of the Finnish alcohol and counter-culture, as witnessed even in the leading engineer school's making-and-use-of video of yore. "Four thousand litres of gases are generated. They are led to the neighbours' delight." The drink tends to invite such black humour, of the deadpan kind. Historical variants Kilju had to be modified before 2018 in Finland, so grain, potatoes, fruits or berries were used during fermentation to avoid legal problems and to flavor the drink. Oranges and lemons are a popular choice for this purpose. Flavored kilju Flavored kilju from fruits for