_Four-Pound Paper._ This class of carbon paper has a heavy, sensitive coating, and is intended for heavy manifolding—for making from five to twenty copies. Soft-finish carbon papers are always used where heavy manifolding is to be done. The finish of the paper which is being written upon is also a factor. Papers with a hard finish—that is, a shiny surface—do not allow the color of the carbon paper to take hold, and yet a paper with the soft finish will allow the color to spread, and make a poor copy. This class of paper is also used for making a few copies on very light-stroke machines like the Hammond.
_Seven-Pound Paper._ This weight of paper is adapted for making from one to five copies. Being heavier than the four-pound, it will wear longer. If coated heavily it will give more impressions than if lightly coated, but the impressions will not be as clear and clean.
_Ten-Pound Paper._ This weight of paper is intended for use where one or two copies are wanted. Its weight enables it to stand the hard usage to which it is put. On one or two copies, the additional weight or thickness of the carbon paper does not affect the imprint. This class of paper is used with billing machines of all kinds.
_Full Carbon Papers._ This is a paper which is coated on both sides for making a multiplicity of copies on tissue. The pieces of carbon paper are placed between _every other piece_ of tissue paper and manifold on the top of one sheet and the bottom of the next. This carbon paper is used to reduce the bulk of paper in the typewriter—one-half as much carbon paper being required. It is sometimes called _double_ carbon paper, and is mostly used by railroads in making up way bills on yellow (dandelion grade) tissue paper.
_Copy Carbon Papers._ This paper is for use where it is necessary or desirable to make a carbon copy from which to make a letter-press copy. Hektograph carbons are for making carbon copies to be used in a hektograph.
_Pencil Carbons._ This class of carbon paper is made in the heavy grades of paper from seven-pound to twenty-pound and is made full carbon in the seven-pound weight.
_Pen Carbon._ This class of carbon paper is made in the seven-pound and ten-pound weights.