Egg tempera is a terrific medium with many advantages. It is safe, non-toxic, and permanent. Unlike oil paint, it will not yellow, change in color, or grow transparent over time. Unlike acrylic, it has a proven track record going back hundreds of years. Egg tempera shows the beauty of pigments off to great advantage. Colors are clear, bright, and pure.

Since you mix your own paints, you know everything that's in them. There are no proprietary recipes or secret ingredients that could compromise your art.

Granted, it has some drawbacks and isn't for everybody.

Egg tempera must be painted on a rigid surface, such as a wooden panel. It cannot be used on paper or canvas. Although egg tempera dries to a tough film, it also grows brittle. It will flake off a flexible surface.

Furthermore, the painting surface is prepared in a labor-intensive manner using chalk gesso, a special kind of plaster. You need this white, slightly absorbent surface; regular acrylic gesso will not do. It's not odious work, but it takes some preparation.

You cannot paint thickly with egg tempera. You must use thin layers, or it will crack. Impastos, knife-painting, and heavy, textured brushstrokes should be saved for other media.

Finally, as with any quick-drying paint, smooth, blended effects take a great deal of work. Acrylic painters live with this, too, of course.