Photo Development puzzle (darkroom, Red Light Bulb and Cold Chisel)

Where the puzzle is

The darkroom is in the film school. Its lamp holds a White Light Bulb that has to be swapped for a red one, and its trays are empty.

The parts are spread out: the Cold Chisel is in the theater, the blood that turns the bulb red is on a table at the top of the 1st-floor spiral staircase, and the Chemicals are in the 3rd-floor apartment bathroom.

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What you need

• Photo Roll: on the floor of the 1st-floor theater lobby
• Cold Chisel: the last theater box, which opens after Film Canister 3 (or the full film) is played
• Photo Paper: in the film school (the exact spot is not confirmed)
• White Light Bulb: the darkroom lamp
• Red Pentacle Stone: from Fumus, to open the 3rd-floor bathroom

Exact spots for each one are on Items and collectibles.

Step by step

1. Take the Photo Roll and the Cold Chisel

   Play Film Canister 3 (or watch the whole film). Then pick up the Photo Roll and the Cold Chisel from the theater area.

   

2. Collect the Photo Paper and the White Light Bulb

   Pick up the Photo Paper and take the White Light Bulb out of the darkroom lamp.

3. Break into the room at the top of the spiral staircase

   Climb the spiral staircase on the 1st floor. Use the Cold Chisel on the boarded door, then hit the door to break it open.

4. Turn the bulb red

   Use the White Light Bulb on the blood on the table inside. It becomes the Red Light Bulb. Be ready: an ambush follows.

5. Fetch the Chemicals

   Use the Red Pentacle Stone on the bathroom door in the 3rd-floor apartment and take the Chemicals.

6. Set up the darkroom

   In the darkroom, put the Red Light Bulb in the lamp and pour the Chemicals into the trays.

7. Make the negative and print it

   Put the Photo Roll on the north table to get the Negative. Then use the Negative with the Photo Paper on the north-west table, and place the Printed Photo in the trays to develop it.

8. Frame the photo and use the stone

   Use the finished Photo on the frame in the 3rd-floor bedroom and take the Hexagonal Stone. Use the Hexagonal Stone on the symbol door on the film school's 2nd floor.

If it doesn’t work

The darkroom won't print anything.

Order matters: red bulb in the lamp and Chemicals in the trays first, then the Photo Roll on the north table, then Negative plus Photo Paper on the north-west table, and only then the Printed Photo in the trays.

The boarded door at the top of the stairs won't break.

Use the Cold Chisel on it first, then hit it. The chisel comes from the last theater box, which needs Film Canister 3.

I can't get into the 3rd-floor bathroom.

It is sealed and needs the Red Pentacle Stone, dropped by Fumus behind the Cow Skull door.

Sources

1. Tenebris Somnia - All Puzzles & Solutions Guide by iampanax Timestamps used: 27:27–34:20
2. Tenebris Somnia Full Game Walkthrough - All 4 Endings [No Commentary] by iampanax Timestamps used: 2:11:10, 2:14:25, 2:19:08