• cobalt(II) chloride
  Cobalt(II) chloride
  Cobalt chloride is an inorganic compound of cobalt and chloride, with the formula CoCl2. It is usually supplied as the hexahydrate CoCl2·6H2O, which is one of the most commonly used cobalt compounds in the laboratory. The hexahydrate is deep purple in color, whereas the anhydrous form is sky blue...
  
   (toxic) (blue to pink)
• copper(II) chloride
  Copper(II) chloride
  Copper chloride is the chemical compound with the formula CuCl2. This is a light brown solid, which slowly absorbs moisture to form a blue-green dihydrate. The copper chlorides are some of the most common copper compounds, after copper sulfate....
  
   (yellow to blue)
• There are other colors like orange
  Orange (colour)
  The colour orange occurs between red and yellow in the visible spectrum at a wavelength of about 585–620 nm, and has a hue of 30° in HSV colour space. It is numerically halfway between red and yellow in a gamma-compressed RGB colour space, the expression of which is the RGB colour wheel. The...
  
  

See also

• Moisture analysis
  Moisture analysis
  Moisture analysis covers a variety of methods for measuring moisture content in both high level and trace amounts in solids, liquids, or gases. Moisture in percentage amounts is monitored as a specification in commercial food production. There are many applications where trace moisture...
  
  
• Humidity indicator card
  Humidity indicator card
  A humidity indicator card is a card on which a moisture-sensitive chemical is impregnated such that it will change color when the indicated relative humidity is exceeded. This item is an inexpensive way to quantify relative humidity levels inside sealed packaging...
  
  
• Desiccant
  Desiccant
  A desiccant is a hygroscopic substance that induces or sustains a state of dryness in its local vicinity in a moderately well-sealed container....
  
  
• Chemical Sensitive