2010年7月27日星期二

Nickel in Watches Causes Allergic Reactions - Part I

If taking into consideration watches than it is necessary to mention the possible contact of skin with the case or bracelet of the watch. Another reason for an allergic response of one's skin refers to the fact that nickel is liberated quite easy from its alloy and onto the skin. It liberates in the form of positively or negatively charged particles. Positive ions can be transported by a fluid, which serves as an electrolyte. Very often the electrolyte is sweat, however the particles can be transported by water from the sea or from a swimming pool. The stainless steel, which is used to make watch cases, is the one that liberates nickel ions in different amounts. The amount of liberated ions depends on the nature of the alloy as well as the proportions of the individual components. Note that stainless steel made for medical purposes practically does not liberate nickel ions. People that are are allergic to nickel should avoid wearing costume jewelry made of nickel silver. The allergic reaction often shows up in the form of dermatitis. A very important factor linked with liberation of nickel ions concerns the condition of metal su***ce that comes in contact with skin.Invar has a very low coefficient of expansion) and Elinvar (variation of Invar). The discoveries of the new alloys were of great use mainly in precision pendulum rods, watch balance springs, as well as thermostats, length standards. What causes allergies to nickel?If a sensitive skin of a person is in direct contact with a certain object containing nickel, there is a possibility that the allergic reaction occurs.