Wikipedia defines enamel as " a smooth, durable coating made of melted and fused glass powder". In addition to kitchenware, enamel was used on appliances, signs, sinks, wash tubs, and much more.
While enamelware is relatively safe, one should use caution when cooking with it. According to Dolores Monet's article, An In Depth Look at Popular Vintage/Retro Enamelware Collectibles,
You may not want to actually cook with vintage enamelware. In the old days, few regulations prevented the uses of toxic materials. Despite manufacturers claims that enamelware was clean and sanitary, additives like lead and cadmium were often used in the production of bright colored frits. For instance, Le Creuset used cadmium in red and orange colored enameled iron cookware. The company still produces red and orange products but now complies with standards set by California regulations, some of the strictest guidelines in the world. While cadmium is still used, production methods prevent the toxin from being released during cooking. Also, the inner cooking surfaces are white.
Years ago, a type of uranium used in the frit for brightly colored enamel was radioactive. US government regulations stopped the use of uranium based compounds used in the production of cookware in 1938.
Today there is some concern that certain countries like China do not provide enough regulation to ensure safe cookware. Inexpensive lead tests are available on the internet and at many hardware stores.
Ms. Monet's article shares how to showcase enamel pieces and provides practical ways to clean and keep enamelware in good condition. (That information can be found towards the end of the article at the link provided.)
Another excellent link with advice on cleaning these vintage pieces can be found at How to Clean Vintage Enamelware.
If you are interested in more detailed information on the history of enamelware, including a timeline that starts in 1761, visit the detailed article entitled History of Enamelware - Kitchen and Household.
Mostly I collect enamelware because the simplicity and the colors make me happy. The following are ways I have found to use enamelware rather than for cooking:
*Collecting kitchen scraps for the compost pile
*As a fruit bowl
*A container when snapping beans or shelling peas
*A pretty serving dish for cold foods such as salads, fruit and slaw
*An ice bucket for family get-togethers
*As a hot water bath canner for jams