Oil Transfer

 Oil transfer is a light blotchy area on the cover (front or back) that results from the oil content of the comic book.

 “Oil transfer” is a defect that is a result of production, but does not take affect till long after leaving the press. It is primarily seen on books of the Bronze Age or older. The producers of the book when buying the inks for the books would specifically buy inks with high oil content and low pigment content because oil costs much less than pigment. The “transfer” arises due to some outer influence (most likely humidity) where the oil separates from the pigment, letting the blotchy area appear. This is a problem commonly found on such books as Giant-Size X-Men #1. Generally speaking, it can be noticed on the back cover the easiest as the the color change from the oil transfer is evident through the tonal changes in the white areas. For example, if looking at the back of a Giant-Size X-Men #1, the outer edges of the cover will be the whitest in color and brightest in tone. Often times, starting about an inch inward from all edges of the back cover, the color will start to darken to a more dull yellow/cream color. In edition to the color change from white to a cream color, it is common for the affect area of the cover to become slightly transparent.