Barolkleen is a treatment for new barrels to remove excess tannin or used as a cleaner to prepare used barrels for storing beer or wine in them. It contains sodium sesquicarbonate, soda ash and lye.
Use 1 pound of Barolkleen per 5 gallons of hot water. Soak in the barrel for 3 days, then drain and flush with water 3 times. Following that rinse the barrel with a solution of 2 ounces of sodium metabisulfite, 1 ounce of citric acid, and 2 gallons of water. Finally give one more final rinse that is water only.