The best brewers make large yeast starters to get their beer fermenting fast. Large populations of active yeast help ensure flavorful beer free of off flavors. Our 1000ml Erlenmyer Flask is the ideal vessel to make a large yeast starter for 5 gallon batches. Because it is made from borosilicate glass you can move it from a boil on your gas stove into a cold water bath for cooling, without the risk of cracking. This means you can do the whole process in one container, keeping it simple and helping to reduce The best brewers make large yeast starters to get their beer fermenting fast. Large populations of active yeast help ensure flavorful beer free of off flavors. Our 1000ml Erlenmyer Flask is the ideal vessel to make a large yeast starter for 5 gallon batches. Because it is made from borosilicate glass you can move it from a boil on your gas stove into a cold water bath for cooling, without the risk of cracking. This means you can do the whole process in one container, keeping it simple and helping to reduce the risk of contamination when transferring from one container to another.