There are thousands of manufacturers in the United States that use lubricants in their metal working processes. Independent machine shops manufacture parts for a variety of different types of metal operations. Many companies have captive machine shops that make parts for their production operations. Examples of the types of processes that use lubricants are stamping, honing, deep drawing, forming, cold heading and tube bending. About half of the lubricants used in metal working today are petroleum-based lubricants. Some of these lubricants are so-called vanishing oils. Vanishing oils are relatively high vapor pressure lubricants that are designed to evaporate from the part over a period of time. These oils are classified as Volatile Organic Compounds or VOCs that contribute to photochemical smog. Other lower vapor pressure lubricants are diluted with mineral spirits or kerosene to obtain the desired consistency for the operation being performed. In some cases, suppliers of these lubricants dilute them; in other cases, the companies using the lubricants dilute them as they are used. The mineral spirits or kerosene in these lubricants are classified as VOCs and, like the vanishing oils, they contribute to smog.