All items listed here can be obtained during your first time in the zone.
Black Mask #1
When you access Industrial proper, hop over the truck and take out the thugs. The first Black Mask is inside the cargo door on the background wall.
Black Mask #2
The next Black Mask can be found two rooms beyond the previous one. When you round the corner, you can spot it atop a locker.
With the Gel Launcher acquired, return to the small room that bridges the piston room with the large room where you fought the multiple thugs. Use the launcher to blow open the rear wall, then crawl through to reach a WayneTech crate with this inside.
Black Mask #3
After blowing the first vertical wall with the Gel Launcher, move into the room ahead. The next mask is atop a locker inside.
Black Mask #4
After battling Solomon Grundy, you'll find this in the very next chamber. Look for it by the drain.
Black Mask #5
Not long after the same chamber, you'll blow a wall and glide into a room near a giant spinning fan. Take out the handful of thugs at the end of the room, then look for this on the desk nearby.
Black Mask #6
After watching Black Mask wander behind a skull and guns logo, you'll be in a room with maintenance tunnels. Hop in and head left to find a replica mask atop a bookshelf in the next room.
Black Mask #7
When you climb through an air duct with a skull logo, pay attention as you round the next corner. The next mask is on a box there.
Black Mask #8
After freeing the hostage, you'll drop down a level. Go through the vent here, and you'll be able to see the mask atop a locker.
Black Mask #9
This is found in the very next room. You'll spot it on a scaffolding in the foreground.
Blackest Night Gloves
When you reenter the elevator shaft by the "B" marking, move right. Head through the vent here and make your way up the platforms. Use the Gel Launcher to blow the pipe up ahead, then grapple up to a ledge where you'll find a WayneTech crate.
Black Mask #10
After climbing the duct out of the elevator shaft, take out the thugs and move left. This sits atop a generator near the room exit.
Black Mask #11
As you enter the elevator shaft yet again, you'll use the Gel Launcher to blow a hole in an upper floor. After climbing up here, look right to spot a mask atop a file cabinet.
Black Mask #12
After taking out the thug by the spotlight and his buddy by the magnet, you'll use the Crypto Sequencer to move a crane-like vehicle. When you drop from this, the mask will be atop a generator to your left.
Black Mask #13
Shortly after, you'll blow a hole in a wall near some doors topped with barbed wire. Move through the tunnel, then grapple to the roof above the dead engineer. The mask is on a shelf up here.
Black Mask #14
After a proper ride in the elevator, you'll head through a door on your right. Grapple up the ladder in here to spot another mask on a generator in the corner.
Black Mask #15
Once you activate the pistons you'll start moving to your left (right on the map). When you enter the large sewer room, keep an eye out when you round the corner - another mask is tucked into the pipes along the ceiling.