Add water to 23 in. from top; heat to 130'F. Add 115 lb. corrugating starch; mix 5 minutes and add 16 lb. caustic soda dissolved in water (5 gal.). Mix 5 minutes. Heat to 160'F., hold for 5 minutes and add water to 6 in. from top. Mix 5 minutes and add 3 pt. formaldehyde.