single-ply, 2-ply, 3-ply, and 4-ply. Roll length Phrases like "single roll", "double roll", "triple roll", "jumbo roll", and "mega roll" commonly used in retail advertising refer to the number of sheets per roll (though the actual number of sheets is also usually disclosed on packaging). A longer roll needs to be replaced less often, but the very largest sizes do not fit all toilet paper dispensers, especially in older homes. Materials Toilet paper is usually manufactured from pulpwood trees, but is also sometimes made from sugar cane byproducts or bamboo. Toilet paper products vary greatly in the distinguishing technical factors, such as size, weight, roughness, softness, chemical residues, "finger-breakthrough" resistance, water-absorption, etc. The larger companies have very detailed, scientific market surveys to determine which marketing sectors require or demand which of the many technical qualities. Modern toilet paper may have a light coating of aloe or lotion or wax worked into the paper to reduce roughness. Quality is usually determined by the number of plies (stacked sheets), coarseness, and durability. Low grade institutional toilet paper is typically of the lowest grade of paper, has only one or two plies, is very coarse and sometimes contains small amounts of embedded unbleached/unpulped paper; it was typically called "hard" toilet paper. A brand disinfected with carbolic acid was manufactured in Sheffield, United Kingdom under the Izal brand name by Newton Chambers until 1981. Mid-grade two ply is somewhat textured to provide some softness and is somewhat stronger. Premium toilet paper may have lotion and wax and has two to four plies of very finely pulped paper. If it is marketed as "luxury", it may be quilted or rippled (embossed), perfumed, colored or patterned, medicated (with anti-bacterial chemicals), or treated with aloe or other perfumes. To advance decomposition of the paper in septic tanks or drainage, the paper used has shorter fibres than facial tissue or writing paper. The manufacturer tries to reach an optimal balance between rapid decomposition (which requires shorter fibres) and sturdiness (which requires longer fibres). Compaction of toilet paper in drain lines, such as in a clog, prevents fibre dispersion and largely halts the breakdown process. A German quip says that the toilet paper of Nazi Germany was so rough and scratchy that it was almost unusable, so many people used old issues of the Völkischer Beobachter instead, because the paper was softer. Color and design Colored toilet paper in