Cindy Demand, the hair and make-up supervisor for War Horse, has worked on 39 Broadway shows, including The Producers (a few of the actors had 30 wigs each) and A Free Man of Color ("the hair and costume changes were "lightning fast"), as well as several productions, early in her career, at Hartford Stage: "Mark Lamos, the artistic director, said he would never put an actor in a bad wig - and he didn't."

But I must confess that when I heard her recount her career summary the other day, in the hair and make-up room backstage at the Beaumont, it was her mention of "dirt call" that most spurred my pen to scribble. Demand, who grew up in Queens and studied fashion design at F.I.T., said, "That's something I do one or two hours a week here at War Horse. Dirt and mud are considered make-up, so it's my job to get them together."

This is serious business. In her research for War Horse, Rae Smith - the costume and set designer for War Horse - discovered that the mud around the River Somme, in France, where the play's battle scenes take place, is a very specific grey, not fifty shades of it. So Demand must achieve that tone when she mixes her concoction.

"The mud is made up of theatrical powder - several colors must be mixed together to achieve the right grey. I mix these with water and a little glycerin. The glycerin is so the mud doesn't dry out. Everybody gets a little pot of it for their dressing table, to use when they are making up. The women in the show apply the mud but don't wear much make-up otherwise. Cast members mostly do their own make-up." 

Demand, whose mentors include Paul Huntley, whom she calls "the gold standard" when it comes to hair and wig design, does help almost half the cast apply their facial hair. "They come to me around 30 minutes or so before curtain. I help them glue or tape on the pieces - sideburns, mustaches." Demand showed me some of these pieces. They are light as a feather, and match the actors skin tones seamlessly.

"The matching is essential," she said, "because hair in a show must look real. We deal in reality when it comes to hair. We're not running a beauty salon."

If you passed Demand's room on a Thursday or Friday afternoon, however, you could be forgiven for thinking otherwise. "We give haircuts on those days to cast members. Actors get a haircut every three weeks. But there's no shampoo before the cut. Soldiers in the First World War didn't use it."

Brendan Lemon is the American theater critic for the Financial Times and the editor of lemonwade.com.