The outer layer of the hemp stem is where the longer liber fibers come from, while the inner woody core is referred to as hemp branches. Both types of fibers can be used to make hemp paper. Paper made from long liber fibers is thin, brittle and thick, while paper made from hemp leaves or pulp is thicker and softer. Hemp paper is a type of paper that consists entirely or mostly of pulp obtained from industrial hemp fibers.
It is mainly used for special papers, such as cigarette paper, banknotes and technical filter papers. Compared to wood pulp, hemp pulp has four to five times longer fibers, a much lower lignin fraction and greater tear and tensile strength. However, since the paper industry has been optimized for wood as a raw material, production costs are currently much higher than those of wood paper. Gmund Paper, a German company with one of the oldest papermaking machines in use, has been able to modify its machine to work with these extra-long hemp fibers and can therefore offer papers with a higher hemp content.
In 2000, the production of flax and hemp pulp totaled 25,000 to 30,000 tons per year, resulting in a production of between 37,000 and 45,000 tons of fibers. Hemp paper is mostly used for special applications and not for mass applications such as printing, writing and packaging paper. In Germany, the Betäubungsmittelgesetz (Narcotics Act) completely banned the cultivation of hemp between 1982 and 1995 to prevent the illegal use of cannabis as a narcotic. In France, however, varieties of hemp used for cigarette paper were still cultivated (see Hemp in France).
Production costs are approximately four times higher than those of wood paper due to the lack of infrastructure for hemp. The chemical composition of hemp leaves is similar to that of wood, making it an ideal raw material for making paper. Although industrial hemp obtained in the 1950s and 1960s is harmless due to the almost total absence of THC, its cultivation has been banned in many countries in recent decades. Between 1934 and 1935, hemp cultivation began to increase but still at a very low level without a significant increase in the paper derived from hemp.
Merrill created paper made from hemp pulp and concluded that the role of hemp stems was favourable compared to those used with wood for cellulose. In 1994, most of the French hemp crop was used to make rolling paper, currency and high-quality paper for Bibles (paper from India). The first identified thick paper made from hemp dates back to the early Western Han Dynasty 200 years before Cai Lun's nominal invention of papermaking by improving and standardizing paper production using a range of cheap materials including hemp tips about 2000 years ago.