How did you get your start as a scenic and lighting designer? My dad was a scenic and lighting designer. When I was a kid, I'd be in the shop taking the scrap wood and building little things. Before he passed away, I would be in the middle of tech and have a problem I couldn't wrap my head around, and I could call my dad. I miss the shit out of him all the time, and I definitely miss the shit out of him when I'm hitting roadblocks.

Once you've read a play and met with the creative team, what's your next step as a designer? The first research I do is more emotional, finding imagery that is emotionally resonant with me the same way the play is. One book I always go to is the works of Mark Rothko—I'll flip through the pages, waiting for something to hit me like "That's the blue. That blue hits my heart the same way the play does."

Did you find a Rothko for your The Hound of the Baskervilles set at Seattle Rep? There are a couple of his paintings that are almost black with limited variation in tone—it's almost more a texture than anything else, like a soft, blurry horizon. It felt like the moor to me, and that sense of a void being both vast and claustrophobic at the same time. There's a darkness to the character of Sherlock Holmes himself—him being a drug user, his social ineptitude that sometimes borders on Asperger's syndrome, this need to feed his mind and his sense of excitement.

Then you draft and make models, right? Everybody still makes physical set models. It's an important tangible thing—the thing you show at first rehearsal that people get really excited about. Then it sits in the rehearsal hall for when a director and an actor have a blocking question they can't wrap their heads around. They can walk over and look at it and say, "Well, the couch is here, but what if we put it over here?" and physically shove things around.

How has your design sense changed over the years? I'm more interested in substance than surface—it's really easy to get excited when you're young about moving lights and fog machines. That stuff is great (there's a shit-ton of fog in Hound), but you have to ask "Why?" When I was younger, the answer was more "because" or "because it looks cool," and that's not a good answer.

Can you give me an example? The Glass Menagerie at the Rep in 2012. I did the lighting design. I told Braden Abraham, the director, and Mikiko Suzuki MacAdams, the scenic designer: "You guys have to keep me honest about not making everything too pretty." There's a griminess to the story, but there's a temptation to romanticize it and make it look pretty. Sheila Daniels taught me that when I worked with her on Abe Lincoln in Illinois at Intiman. At the end of the show, when Lincoln is up on this rolling platform, I'd written a really pretty light cue. Sheila came back to the tech table and said, "That's really gorgeous, but this isn't a gorgeous moment—he's going off to start a war, and there needs to be some of the pain of that." I was heartbroken for half a second, and then I said, "Yes, of course, you're right."

What were some of the design challenges for Hound? We go to 18 different places in the course of the show—there is a lot about the script that feels cinematic, but it has a strong momentum that is specific to theater, so we wanted to come up with a design that is fleet, able to shift and change and sculpt our world and perspective quickly. We had a conversation about limiting the amount of stuff onstage. Baker Street [Holmes's apartment] could be a fireplace, wall hangings, tables, chairs, pipes, and deerstalker hats. But for this production, there's just a breakfast table, an armchair, Holmes's study hutch, and a pair of windows that come in. It's simple, but it really specifically sets the location.

More Seattle theatergoers seem to talk about design than they used to. At the Rep, we do these lobby talks before shows, and there will be 150 to 200 people showing up early to hear designers talk. Lighting tends to be the most esoteric. We all deal with lighting every day, but it's not something people consider all that much. There's an old adage: "The best review for a lighting designer is the review that doesn't talk about lighting at all." Which is true in some ways and not in others—it's the invisible thing that's not really invisible at all.

L.B. Morse is the scenic and lighting designer for The Hound of the Baskervilles at Seattle Rep (through Dec 15). He's also the lighting designer for A Great Wilderness, Jan 17–Feb 16, also at Seattle Rep.