trednot 4 oz steel blackening concentrate, makes 2 1/2 pints, bluing solution, gun blue/black trednot 4 oz concentrate for blackening steel. mix 9 to 1 with water. makes 5 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 one 4 oz bottle of concentrate will make 40 ounces (2 1/2 pints) of solution and will blacken many items. may be stored after it is mixed for blackening at a later date. will not blacken stainless steel, aluminum, lead, or copper. usa shipping only. i will not ship internationally.