The unexpected appearance of dark particles or discoloration in a product raises concerns over the integrity of the product and can cause consumers to reject it. In order to catch problem products before they reach consumers, quality control laboratories typically examine a product’s appearance, as well as other properties, before it is released. Particulate contamination in products can originate from a wide variety of sources via raw materials or from debris in the manufacturing environment. Common types of particulate include metal wear products or corrosion, paint chips, shredded plastic, glass chunks, hairs and insect parts. In some cases, particulates or discoloration also may arise from the agglomeration of ingredients or reactions between ingredients and contaminants.
When particulate contamination or discoloration is observed, the next step is often to pass the sample on to an analytical chemist to identify the nature of the contaminant or discoloration. Samples are generally submitted by quality control or stability testing laboratories, plant engineers and consumer complaint coordinators. Identification is an important step in the process of tracing the origin of the problem so that it can be fixed, safety concerns can be addressed, and in some cases, responsibility for the costs incurred can be assigned.