oil spots, fig. 4
Fig. 4, Black spots and black spots with white centers.
The spots are more pronounced if the film is exposed after it is coated with oil because the oil acts as a negative and produces a printed image.
ex G. E. Matthews and J. I. Crabtree,
Oil Spots on Motion Picture Film, paper No. 325 in Abridged Scientific Publications, Research Laboratories of the Eastman Kodak Company. Vol 12 (1928)
17 February 2012