4 oz concentrate for blackening steel. Mix 9 to 1 with water. Normal 0 Makes 5 cups (over 1 liter) of blackening solution. Works in 2-6 minutes. The pictures show steel objects submerged for 30 seconds. Significant blackening action takes place in 30 seconds. Directions instruct to submerge for 2-6 minutes. This one 4 oz bottle of concentrate will make 40 ounces of solution and will blacken a LOT of items and you can store it after it is mixed for blackening at a later date. Normal 0 It will not blacken copper, brass, or stainless steel, Here is some feedback from customers: Normal 0 Great item. Very fast shipping. Works awesome. Gun looks brand new Buyer: Member id kaplanj1189 ( Feedback Score Of 206) ————————————————————– AWESOME this is the best gun bluing chemical i’ve ever seen, i’ll be buying more Buyer: Member id amcg5835 ( Feedback Score Of 73) great product using at my gun shop excellent service and timely delivery awesome !! —————————————————Buyer:Member id ofdunk Great stuff ! Gives quality results and is easy to work with. Thanks! —————————————————————————-Buyer:Member id ad5lq ( Feedback Score Of 600 Seems to work well at 6-8:1. Bargain compared to Retail bluing————————————————————-Buyer:Member id iseecrap ( Feedback Score Of 302 Powerful stuff! Works great !!! AAA+++++————————————————————– NO INTERNATIONAL SHIPMENTS