Materials used for case construction should be chosen carefully because component materials can easily become a significant source of pollutants or harmful fumes for displayed objects. Outgassing from materials used in the construction of the exhibition case and/or fabrics used for lining the case can be destructive. Pollutants may cause visible deterioration, including discoloration of surfaces and corrosion. Examples of evaluative criteria to be used in deeming materials suitable for use in exhibit display could be the potential of contact-transfer of harmful substances, water solubility or dry-transfer of dyes, the dry-texture of paints, pH, and abrasiveness.