The transformation scene was done in much the same way the beginning part of the transformation was done on Dr. Jekyll and Mr. Hyde (1931). The actress was made up in exaggerated highlights and shadows (including her teeth) using a single color shade of makeup. When filmed through a filter the same shade as the makeup, it's invisible to the camera. Take the filter away and the makeup suddenly becomes visible. Besides a filter, the makeup can also be hidden by similar-colored light. This type of trick was only possible on black-and-white film.
Once thought to be lost, now available on DVD through Warner Archives in the Warner Bros. Horror Mystery Double Features set.
Nanny's transformation which sees a cackling, but otherwise normal-looking woman transform into a gnarled, blotchy hag relies on the same red-blue color filtration found in old-school 3-D glasses. When you look through the red lens of a pair of 3-D glasses, you don't see the red elements on-screen. The same is true of the blue elements when you look through the blue lens. When you apply this concept to black-and-white photography, you are able to "hide" certain colors in plain sight. It's worth emphasizing that this optical makeup effect is only possible on black and white film. If this scene had been shot in color, Nanny would have appeared weird. But the "reveal" gag wouldn't have worked quite as well, if at all. Nanny's "ugly face" makeup was applied using one color of product, exaggerating and creating unfaltering shadows, contours, and blemishes on Dudgeon's face. Colored makeup was also used to "blackout" some of Dudgeon's teeth. A graduated filter was placed in front of the camera lens. At the beginning of the scene, we are looking at Nanny through the red-colored filter, which is "filtering" out any red that it "sees." Consequently, Dudgeon's red makeup appears to blend into her skin tone and the grotesque visage appears invisible. As the filter is slid across the front of the camera lens to the blue side, the splotchy red makeup becomes visible to us. And because we're working with black-and-white film, the red appears to darken. Whether the crew also supplemented the graduated filter with a colored light (which would enhance the effect) is unclear, but possible. Two non-makeup elements that further sell Nanny's metamorphosis are her hair and eyes. The stark difference between her silver, tied-back wig and the stringy, dark mess beneath it enhances the contrast of the shift. To boot, if you look at the transformation scene frame-by-frame, it's clear that the motion of the wig removal itself has the added effect of smoothing over any awkwardness in the color filter shift. Because the filmmakers moved the color filter in front of the camera lens at the same time Dudgeon removes her wig, our eyes wander around the frame, and the transformation feels much smoother and organic as a result. The change in Nanny's eyes is especially upsetting. At the beginning of the shot, Dudgeon's irises are pitch black, an early indicator of the horrifying shift to come. Then, when her hag-form is revealed, Dudgeon's eyes lighten and sparkle. While there's an impulse to cry "colored contact lenses!" here, I don't think that's what's going on. Instead, I think we're just witnessing the natural shift in Dudgeon's eyes as the red and blue are blocked out, respectively. There's something about the sudden "wetness" in Dudgeon's eyes that really sells her final form. It adds an uncanny level of liveliness to a makeup job that otherwise could look quite severe. Another small detail that adds to the holistic power of the effect is the subtle shift in Nanny's shawl. At the beginning of the scene, we can see delicate details and swirling patterns in the garment. And as she becomes the hag, Nanny's shawl responds by "turning" completely black. The changes in both Dudgeon's clothing and her eyes are consequences of the shift in the colored lens, which would have filtering out all of the blue.
The plays referred to in the writers section are "The Gorilla," written by Ralph Spence. which opened in New York in 1925 and ran for 15 performances; and "Sh, The Octopus," written by Ralph Murphy and Donald Gallaher, which opened in New York in 1928 and ran for 45 performances. The original Broadway cast of "Sh, the Octopus" included Beatrice Allen, Clifford Dempsey, Gavin Gordon, Harry Kelly, Ignacio Martinnetti, Francis M. Verdi and Adele Windsor.
One of ten movies to feature character actors Hugh Herbert and Allen Jenkins - and the only one in which their characters were paired as a team - the other nine being Bureau of Missing Persons (1933), The Merry Frinks (1934), Miss Pacific Fleet (1935), Sing Me a Love Song (1936), The Singing Marine (1937), Marry the Girl (1937), The Perfect Specimen (1937), Gold Diggers in Paris (1938), and Stage Door Canteen (1943).