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Practical use for noxious weeds and crop residue


by Denise DeMarie


Paper isn't made from trees. Paper is made from fibers.

So, plants that are on the noxious weed list, are currently being burned as crop residue or sprayed to control growth in waterways and roadsides could be considered good candidates to put to practical use in small scale paper-making. Results are not too difficult to obtain and the paper presents a tangible prototype for larger scale possibilities. At the same time, this diversification could ease dependence on trees for paper products.

The majority of plants work well for paper making, depending on their yield of cellulose. However, some require far too much processing and yield little for the effort.

Therefore, the first step in paper-making is to perform a crude fiber quality test. The plant part which is intended for use is torn crosswise. If the tearing is difficult, tends to change direction and follow the grain lengthwise, the fiber strength of the plant is adequate to experiment with paper-making. Good examples of this are grasses, thistles, and nettles. Poor examples are tender lettuce, brittle leaves, and some tree barks. If a plant proves too tough to tear, it will need more extensive processing.

Sometimes a plant which tests poorly at an early growth stage becomes a better source as the plant ages and toughens. Processing the same plant at different stages of growth can result in a range of paper quality from tissue to cardboard. Also, collected plants can be dried for later use.

Step two in paper-making involves processing the collected plants to break down their non-cellulose contents such as: gums, lignins, resins, silica and fatty materials.

To do this, the plants are cooked in a high alkaline solution of either soda ash or lye. It may be preferable to run the plants through a garden shredder prior to cooking. If the plants have been dried, they should be soaked overnight, then drained before cooking. The plant material is put into a stainless steel pot with enough cold water to cover it. The lye or ash is then added.

When using lye, the solution is 1/2 cup of lye for five gallons of water; a 1:130 ratio. When using soda ash, more may be needed to achieve the same desired results. The object of this step is to raise the pH to 13. The whole works are then boiled for three hours, and left to cool overnight in the hot solution. These ratios and cooking times are intended as guidelines only. The actual formulas that work best vary from plant to plant, and region to region. It's advisable to prepare a small batch of each new plant before processing a large quantity. Grasses, leafy, or soft stalked plants are easiest to process.

The cooking stage is completed when the plant separates easily. A portion pressed between the fingers should spread into separate fibers. If the plant presses into mush, with no body left at all, it has been cooked too long. If it is still tough and hard to tear or separate, it should be cooked longer. Keep in mind that the pot will continue to "process" the plant as the batch slowly cools.

The next stage is rinsing. The plants must be rinsed until they feel free of slippery residue. Pulp that is not rinsed long enough makes poor, brittle paper.

A strong water spray is preferable while rinsing. This has a duel action of breaking down the plant material while cleaning it.

From this stage, a textured paper can be made, or the pulp can be further refined with the use of beating.

Beating can be done by running small batches through a blender (blend very briefly), by hand-pounding the pulp using a baseball bat, or with a mechanical beater made especially for this process. The hand beating method is especially effective at separating and working the fibers without actually cutting them.

With every type of paper-making method used, a different quality of paper can be produced.

One simple method is to suspend the pulp in a tub or vat of water. Then, a mould and deckle are dipped and lifted through the water to catch the pulp fibers. The fibers overlap and compress with this action, and can be left to dry. When dry, the paper will easily separate from the mould. This is called the restraint drying method.

A mould is a rectangular frame supporting a mesh or screen stretched across it. The deckle refers to the top fitting over the mould and "framing" in the shape that is desired for the sheet of paper. Deckles are sometimes round or envelope shaped. A mould and deckle can be as simple as using two wooden picture frames, with a piece of rigid screening sandwiched in between. Or it can be an elaborate, more expensive piece of equipment.

The above described process also works well with agricultural by-products such as corn stalks. Further processing in necessary when using palm fronds or woody stems from old mint stalks and segabrush, or cedar bark as the fiber sources. These sources of fiber must be cooked longer, and beaten with either a stick (baseball bat) or mechanical beater to separate the fibers sufficiently.

Some strong fiber plants will not test "done" as described earlier. So, look for a definite change in the plant appearance and how it handles to assess when to move on to the next stages. Fiber plants such as kenaf, hemp, flax, and cotton all need the strength of a mechanical beater in order to process them well enough for paper-making.

For plants which seem to be of less than optimum fiber quality will combine well with other plants to create wonderful papers. Adding portions of kenaf improves almost anything, as well as abaca (banana fiber), sisal, cottons and flax. Many of these are available from suppliers in sheet form, ready for use after reconstituting and minimal beating.

Straw works well when combined with other plants. The straw contributes highly textured qualities to the finished paper when added to plants that get little processing. If added to plants receiving a lot of processing, it will break down quite a bit yielding a smooth paper.


Copyright 1994 REAP Canada

Reprinted with permission. All rights reserved.

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