ScienceBlogs didn't stay down long, but I do intend to write some science+art posts.
Shall we start with light? After all, most crafts, scultures, drawings and paintings are enjoyed primarily visually. Tactile qualities may be of interest, too, but sighted people examine most things with their eyes.
Light is photons, vibrating at certain frequencies known as the visible spectrum. Light can also vibrate at lower frequencies (infrared, microwave) and higher frequencies (ultraviolet). These photons are released when electrons, small particles in orbit around the nucleus of an atom go from a high energy state to a lower energy state. The energy the electron had gained to be in that state has to go somewhere, and it does so in the form of the photon. The bigger the difference between the high, or excited, electron orbit, and its lower energy orbit, the higher frequency of the photon wave.
When we think of light as coming from fire, electricity, or the sun, we are looking at ways the electrons are raised to high enough energy levels that their jumps back release photons.
Then those photos reach objects. Most objects reflect light. Even matte-finishes on beads, acrylic painting, paper collage, etc. meant to reduce shine don't stop reflection. If no light is reflected, a item would seem either completely transparent or completely black. Color comes from an item reflecting light of a certain frequency, while absorbing other light. White objects reflect light across the visible spectrum. The difficulty in mixing colors comes partly from this. After all, the colors you look at are really reflected light, and if the frequencies reflecting off a blend of pigments isn't right, you get dark and muddy colors.