So far, it has been one HOT summer! With the season’s muggy temperatures, comes increased humidity. So, what effect does the summer weather have on your jewelry? Does humidity cause your silver to tarnish? The answer might surprise you.

According to a silver corrosion study published by the  16th International Corrosion Congress, the effects of temperature, humidity, and distance were tested in relation to the corrosion rate. The study found that the independence of the corrosion rate on relative humidity shows that moisture is not a significant factor in the corrosion process. Rather it is the sulfur molecules reacting directly with the metal that stimulates tarnish. While silver is relatively resistant to corrosion in water and oxygen, it does not fare well in the presence of sulfur and therefore silver corrosion will occur in a sulfur containing environment.

Here is where it gets a little tricky. The study showed that the effects of temperature and the distance between the sulfur and silver influence the corrosion rate. The corrosion rate increased as the temperature increased. Why? Sulfur vapor pressure is more intense at higher temperatures. In order for temperature to influence the corrosion rate, sulfur molecules must be present. Therefore, the corrosion rate slows as the distance between the sulfur source and the silver increases.

As the results of the study concluded, temperature and relative humidity alone do not play a major role in causing corrosion. Rather, the interaction between sulfur molecules and the silver surface determines the corrosion rate.

Long story short- keep your silver in a cool, sulfur free environment!

Reference:

Sakai, Jun’ichi, et al. "Sub-micrometer Order Corrosion of Silver by Sulfur Vapor in Air Studied by Means of Quartz Crystal Microbalance." 16th International Corrosion Congress. Sept. 19-24, 2005 Beijing, China.