RC paper don't have this problem and require short washing periods before drying. FB paper require more work than RC papers, yet they are still considered the standard for exhibition, museum, and archival prints. Contrast refers to the paper's difference between pure black and pure white on the exposed paper. A very low contrast paper, grade 0 for example, will not print a deep black or a bright white, only a number of shades of gray. A very high contrast paper, grade 6, print only a few shades of gray between the extremes of a very dark black and a brilliant, blinding white.
Papers come in two styles of grade classification.
Using graded papers means you must buy each paper in each grade you are going to use. Variable contrast papers use separate filters to achieve a contrast range from 0 - 6. You buy only one package or box of the paper and use the appropriate filters to achieve each grade. Tonality refers to the paper's color, also known as its warmth or coolness. Warm tone papers are brownish in color and cool tone papers are blue or purplish in color.