Out of 140 tubes of paint, all but about twenty had not been opened for at least ten years, some for over twenty years. With matches and a pair of pliers I was able to open all but two. The awl was helpful when the paint had hardened, creating a plug at the opening of the tube. Only three tubes of paint required the use of the awl. This method may be used with oil, watercolor, acrylic, casein, gouache, etc.
I find wooden matches to be better for the job than the cardboard matches. They burn longer and are easier to strike. By holding the flame beneath the tube at the base of the cap and rotating the tube over the flame, the paint becomes softened and the cap, with the help of the pliers, can be loosened. Some tubes require two or even three matches. Turn the cap firmly but gently or the tube might give way before the cap and paint will squirt out from the crack in the tube. When this happens, I wrap the tube in plastic wrap or keep it in a zip-lock bag to prevent it from hardening.
Two delightful discoveries during the continued Color Value Chart painting session (Color Exercise #4) were Cinnabar Green and Olive Green. Cinnabar is a beautiful, light value yellow green. Olive is almost black. Two other discoveries in the almost black category were Purple Lake and Indigo.
Another example of drastic differences between pigments can be seen by the example below of the swatches of Cobalt Violet. Cobalt Violet manufactured by Winsor Newton is quite cool whereas the Cobalt Violet manufactured by Couleurs is rather warm. Notice that the pigment by Couleurs is labeled “light hue”. “Light” and “hue” are clues that the pigments will be different, even if the pigments are created by the same manufacturer. It is important to make color swatches to have a record of both the value and the temperature of your pigments.