Pourquoi dit-on ''être dans le coaltar'' (ou le coltar) ?

L'expression ''être dans le coaltar'' signifie qu'une personne est peut éveillée ou très hébétée. Il faut savoir que le coaltar est un goudron issu de la houille et non un dérivé pétrolier. Il est issu de l'anglais coal qui veut dire charbon et tar qui est du goudron.


La comparaison est faite entre une personne molle et endormie qui serait plongée dans ce coaltar qui est collant et gluant. On pense que l'expression vient d'une époque où certains lieux publics n'étaient pas bien ventilés et que les gens devenaient hagards car ils respiraient un air toxique.

Complement internaute :
1. Field of the Invention This invention relates to a method of treating the surface of a steel strip to increase its resistance to the formation of scale thereon. 2. Description of the Related Art The surfaces of carbon steel strips and other steel strips are generally treated by various surface treating methods in order to improve the corrosion resistance and the adhesion of a coating, such as an organic coating, and also to improve the printability and the coating performance of the strip. The surface of the strip may be roughened by a mechanical or chemical method, or it may be subjected to anodic oxidation or the like, to form an anodic oxide coating on its surface. A strip surface treated by such a method is generally coated with a metal, an inorganic or organic coating, a printing ink or the like, or with a laminated film formed by a coating of these materials. When the surface of a steel strip is treated by these methods, scale is apt to be deposited on the surface of the strip during or after the surface treatment. This scale is an oxide of the material used in the surface treatment and has an insulating property.