Impressions reproducing the frontal and dorsal appearances of a human figure are on one side of the cloth only. Their contrast is light, lack well defined contours and are light-gold colored; coloration intensity is due to the colored fibers’ density that is to say to the number of yellow fibers every area measure. There are niether organic and inorganic painting pigments nor chemical agents foreign to linen fibers. There are clear red stains that biomedical researches proved to be bloodstains. No image formed under the bloodstains and this proves it formed after the haematic contribution.

In 1898 Secondo Pia took the first official photo noticing that the negative image looked like a photographic positive and therefore new theoretic and experimental researches began aiming at reproducing the impressions resulting from the body structure, the blood and other agents like liquids.

A classification of the most supported theories about the causes of cloth negativity (assuming it is soaked with aloe and myrrh) originating the body impression is as follows:

-   contact theory: the body image originated through direct contact;

-   vapor theory: the bodily vapors reacted to aloe and myrrh;

-   radiation theory: some kind of thermal or electrothermal energy reacted to aloe and myrrh.

It is important to stress how all the testings were restricted to the face since working on the global image is very difficult.