First, clean the potatoes and cut them into small chunks. Boil the potatoes for 15-20 minutes in 7 gallons of water. After boiling, strain and mash the potatoes. Transfer the mashed potatoes to another pot, add 7 more gallons of clean water, and raise the temperature to 140 degrees F. At this stage, add the malted barley and stir it into the mash as the temperature rises. Maintain a constant temperature of 140 degrees F for around 20 minutes, stirring every 4 minutes. After 20 minutes, increase the temperature to 152 degrees F and run for around 1 hour, stirring every 10 minutes.