trednot 7 oz steel blackening concentrate, gunsmith bluing solution, gun blue/black trednot 7 oz concentrate for blackening steel. mix 9 to 1 with water. makes 2 liters (8 3/4 cups) of blackening solution. works in 2-6 minutes. the pictures show steel objects submerged for 5 minutes. significant blackening action takes place in 1 minute. directions instruct to submerge for 2-6 minutes. this 7 oz bottle of concentrate will make two liters of solution and will blacken steel items. it will not blacken stainless steel, aluminum, lead, or copper. may be stored after it is mixed for blackening at a later date. note: the bottle appears not to be full. this is because there is 7 ounces of liquid in an 8 ounce bottle. a 7 ounce bottle is not available. usa shipping only