IT'S TIME TO RECONSIDER HEMP

by Jim Young, technical editor of Pulp & Paper

June 1991


Let me say up front that I have never smoked a commercially made cigarette, much less that devil weed with roots in hell. Passed through he '60s without a single pair of tie-dyed bell-bottoms.

Identified with more of Merle Haggard's "Okie from Muscogee" than Jim Morrison's "Light My Fire."

Yet, I believe that Indian hemp Cannabis sativa (-yes, that Cannabis) has more to offer the paper industry than we are taking advantage of (or more correctly, we are allowed to take advantage of).

Tradition, if not Federal law, is on the side of hemp, starting with Ts'ai Lun himelf. According to the book, The Emperor Wears No Clothes, by Jack Herer, from 75% to 90% of the world's paper manufactured before 1883 was made from Cannabis hemp fiber, including the Gutenberg Bible and the first two drafts of the Declaration of Independence. Augmenting the tradition of hemp fiber, the USDA in 1916 predicted a papermaking future for nonfiberous portion of the hemp stalk in its Bulletin No.404, Hemp Hurds As Paper-Making Material. Hemp hurds are 0.5-in. to 3-in. pieces of the woody inner portions of hemp that have been separated from the fiber. Hurds contain more than 77% cellulose.

Reporting on papermaking tests with hemp hurds, the bulletin concluded, "Hemp-hurd stock acts similarly to soda-poplar stock, but will produce a somewhat harsher and stronger sheet and one of higher folding endurance... …In fact, the hurd stock might very possibly meet with favor its a book stock furnish in the Michigan and Wisconsin paper mills, which are within the sulphite fiber-producing region."

A long-awaited mechanized breakthrough in removing the fiber-bearing cortex from the rest of the hemp stalk "without a prohibitive use of human labor" was described in a three-page article in the February 1938 issue of Popular Mechanics entitled, "The New Billion-Dollar Crop." Written at the time of the passage of the federal Marijuana Tax Act of 1937, the article included the challenge, "if the federal regulations can be drawn to protect the public without preventing the legitimate culture of hemp, this new crop can add immeasurably to American agriculture and industry." This was not to be, however. Perhaps not coincidentally, the Tax Act uprooted the billion-dollar crop (1938 dollars) before it could be planted.

lt is the dried flowers and top leaves of the female Cannabis sativa, of course, that constitute marijuana. Without opening the debate on its legalization or the psychotropic effects of its delta-9 tetrahydrocannabinol (THC) content, it is worth noting that interest in paper-making from hemp continues as our fiber, energy, and environmental concerns increase.

The '70s was a decade of intensive study of Cannabis papermaking, particularly in Italy, France, Spain and Holland. Different varieties of hemp have been developed for various papermaking applications, depending on the cooking process and end use of the pulp. Concurrent research and selective breeding reduced THC content. In France, farmers must obtain low-THC Cannabis directly from the National Hemp Producers Federation, inform the Ministries of Health and Agriculture of their intent, and have a guaranteed purchaser of their crop.

The high cost of limited production currently restricts hemp to specialty use such as European and Asian cigarette papers. Cannabis hemp can probably be pulped in existing kenaf-pulping equipment, but it will take more than imported stock to make it economically feasible.

Hemp is the world's primary biomass producer, growing ten tons/acre in approximately four months. It can produce four times the amount of paper/acre than 20-year-old trees can and will grow in all climatic zones of the contiguous 48 states.

Pyrolysis of hemp can be adjusted to produce charcoal, pyrolytic oil, gas, or methanol with a claimed 95.5% fuel-to-feed efficiency. Pyrolytic fuel has properties similar to Nos. 2 and 6 fuel oil. Burning charcoal does not cause acid rain.

US hemp-growing restrictions were set aside to meet material shortages during World War II. They should now at least be modified to meet pending shortages of fiber, energy, and environmental quality.