The Chemistry of Art (Rice University)
Kremer Pigmente is a premier source for pigments and dyes, especially those used historically. Kremer publishes Safety Data Sheets (SDS) for all materials they sell which detail any safety concerns regarding a product as well as safe handling procedures.
The Color Index is a classification system devised by the Society of Dyers and Colorists and the American Association of Textile Chemists and Colorists to classify known colorants (pigments or dyes). An open-source version of this index is available at the link above; colorants are classified by color and then code. For example, a blue paint might list that it contains colorant PB15. From the code and using the index, we could deduce that this is a pigment (P) that is blue (B) and is the 15th entry made in the list of blue pigments. The database would reveal its chemical identity as Copper Phthalocyanine and include relevant safety data.
You may want to find more detailed chemical or physical property information about components of paints, pigments, ceramics and other materials. The following databases contain such information as toxicity, solubility, and spectral characteristics. Typically you can search by common names of substances.
CAMEO - Conservation and Art Materials Encyclopedia Online
CAMEO includes 3 databases: 1) The MATERIALS database contains chemical, physical, visual, and analytical information on over 10,000 historic and contemporary materials used in the production and conservation of artistic, architectural, archaeological, and anthropological materials. 2) a DIRECTORY of conservation-related organizations 3) a repository of information on FORBES' PIGMENTS. Created by MFA Boston