Egg tempera is a form of painting that uses powdered pigments mixed with egg yolk. It was very popular during the early Renaissance, and Botticelli’s Birth of Venus is just one example of a famous painting in this medium.
Although it doesn’t produce colors as rich as oil paints, tempera paintings have lasted without color loss for many centuries. It’s also a form of fast-drying paint you can make yourself with nothing but eggs and cheap watercolor pigments (you can actually use almost anything to make pigments, but do your research because some ordinary substances become toxic when they’re ground up small enough to be inhaled – it’s simpler to stick to watercolor cakes). It’s not easy to master, but it’s a lot of fun as a hobby because it dries so quickly that you can achieve different effects than oil or acrylics allow. You can also use it to make decorative objects from templates or stencils, regardless of your level of artistic talent. It can also be a very cheap way to recycle your kids’ unused watercolor cakes into something new and exciting they’ll play with for hours.
You can make your own palette of egg tempera colors and get started with this great tutorial from Instructables. YahooGroups has a whole group devoted to egg tempera where you can discuss your learning experience with others. RealColorWheel offers a ton of information on various egg tempera and oil-over-egg techniques you can try, along with some suggestions you can try on your own. And WaterColorPainting has yet another page of information.
This site about fantasy painting has some great tips from users about things they add to their pigments, such as vodka or various types of oil.
In case you’re wondering: yes, after a few hours, the painting (and paints) will begin to smell. That’s okay – just put them somewhere to dry, and the smell will go away.