With 150 different colors, Prismacolors's "Softcore" line has the most color variation of all their colored pencil lines. They have an 8mm round barrel, which matches the 5mm diameter wax core. Softcore pencils can be bought individually or in tins that separated the layers of pencils inside with plastic. The tins come in pack variants of 12, 24, 36, 48, 72, 132, and 150. The wax they are made with allows them to be smoother and easier to blend. However, it also causes frequent breaks when pushing down or sharpening the pencil. Some artists microwave them to try and fix this common problem. Another common problem is called "wax bloom." This occurs when there is more wax in colored pencils then there is pigment, or in users who are heavy handed. It causes a wax film to appear over the places the pencil is used, which makes the work look more white or "washed out." Wax bloom can be removed by gently rubbing the affected area with a soft cloth or tissue. Afterwards, some people choose to spray a fixative onto the end product to prevent re-occurrence.