The pair form Carter White FX, a make-up effects company that specialises in prosthetics and animatronix, the art of making lifelike moving creatures for films and television. "We can design and make anything," says David, "from a life-sized animatronic ape to an oversized walking, talking, belching bacterial germ. We read the script first, make some designs, and take it from there."
The process of making prosthetics is a lengthy and time consuming job. Two or three days of pre-production went into the making of Sacha's standard hag/witch prosthetic alone. David explains the steps.
"A cast must be taken of the actor's face. Then the prosthetic is sculpted over the top of it in Plasterlene. Fibreglass is then brushed over the Plasterlene to make a mould. When that has set and dried, foam latex is pumped into it to form the prosthetic. When it has then been baked in an oven, the prosthetic is painted for effect and only then is it ready to apply to someone's face."
When you think that prosthetics can only be used once and that hundreds of them are needed on some movies, the process seems mindboggling.
David White started in the industry 14 years ago, when he became fascinated with the special effects in films like The Evil Dead. He bunked off from art school and rang round all the studios, eventually being hired as an assistant on Krull, at Pinewood, for pounds 48 a week.
Since then he has made everything from the 15ft dancing plant in The Little Shop of Horrors to Mole's nose and Rat's ears in the forthcoming Wind in the Willows film. He also did the moving, talking boil in How To Get Ahead in Advertising, and most notably, Robert do Niro's head-to- toe makeover in Kenneth Branagh's Frankenstein. The last two decades have seen a massive boom in the special make-up effects industry.
"An American Werewolf in London, made in 1981, was the first film to win an Oscar for make-up effects and really drew attention to the industry," says Sacha. Up until then, although prosthetics had been around in a less flexible form (the witch in The Wizard of Oz for example), early horror films, like The Hunchback of Notre Dame, had relied heavily on lighting and shadows to create effects.
Then came an American make-up artist called Dick Smith, who revolutionised the industry with horror film classics like The Exorcist, The Fury and Altered States as well as giving away many of his secrets by writing a DIY make-up book. On the back of these films the Schlock Horror genre was born, spawning The Evil Dead and the Nightmare on Elm Street series, and a whole host of straight-to- video exploding head and rubber monster movies which were extremely popular with the middle American teen market.
While there is money to be made from splatterfests, the pair prefer the more stylish cinematic horror classics. "Like Alien," says Sacha. "It was one of the first movies to be subtle about horror. Sometimes you saw the creature, sometimes you didn't. What they did was 'suggest' that there was something really, really horrid on board the spaceship, which is far more frightening than seeing it up close."
These days, with the advance of computer technology, the FX industry is undergoing yet another technological revolution. "Computer graphics marry the two art forms," says David. "Prosthetics and animatronics are enhanced by computer graphics so that the effects are so good that you can make almost anything come to life."
But again, this simply makes for astonishing effects, not necessarily great cinema. "The Mask was good because it was funny and the effects were new," says Sacha. "But Jurassic Park was a case of the effects being better than the movie."
Meanwhile, our photographer has snapped his last roll of film, night has fallen and Sacha's face suddenly doesn't seem so funny. "There's a Jekyll and Hyde in all of us," she says. "In this I get to be my Ms Hyde."
How to do horror make-up ...
Fake nose and chin: use mortician's wax from a theatrical make- up shop. Warm it up and sculpt into noses, ears, chins.
Fake teeth and nails: cut false nails into points, file down into grooves, dirty up with paints. For teeth, use plastic vampire ones, or peanuts stuck to a chewing-gum palate. Colour them red with food dye.
Eyes: buy yellow or red tinted eye drops from theatrical make-up shops.
Where to buy it...
BIRMINGHAM Masquerade, Hagley Road West. Horror and theatrical make- up, vampire and devil kits, pounds 3.99, etc.
CAMBRIDGE Wardrobe, 27 Cromwell Road. "We have whatever casualty simulation you want!" Blood comes in "vein" or "artery", they also do bullet holes, burns, scabs, scars ...
LONDON C H Fox, 22 Tavistock Street, WC2. Sell spine-tingling special effects such as worms emerging from ears, cut-open skulls, stick-on warts, and "wound filler" to put into a latex cut. Uggghh.
Escapade, 150 Camden High Street, NW1. Try their purple or white Horror Flesh (pounds 2.99).
Screen Face, 24 Powis Terrace, W11. Horror make-up includes stick-on noses, ears, scars.
LOUGHBOROUGH Stage Services Prince William Road. Staff trained in face painting, they also sell scar wax, "corpse" face paint, etc.
REDDITCH Reddi's Fancy Dress Hire, 149 Ipsley Street, Smallwood. Choose white face paint, or The Mask masks.