Curing - As suggested by Mel Frank & Ed Rosenthal

Curing
Curing is a process employed to naturally enhance the bouquet, flavour, and texture of marijuana. Curing does not lower potency when done correctly, although poor curing methods often result in some less of THC.
Curing is not an essential procedure, and many growers prefer the "natural" flavour of uncured grass. Sweet sinsemilla buds usually are not cured.
Curing is most successful on plants which have "ripened" and are beginning to lose chlorophyll. It is less successful on growing tips and other vigorous parts which are immature. These parts may only lose some chlorophyll.
Curing proceeds while the leaf is still alive, for until it dries, many of the leaf's life processes continue. Since the leaf's ability to produce sugars is thwarted, it breaks down stored starch to simple sugars, which are used for food. This gives the grass a sweet or earthy aroma and taste. At the same time, many of the complex proteins and pigments, such as chlorophyll, are broken down in enzymatic processes. This changes the colour of the leaf from green to various shades of yellow, brown, tan, or red, depending primarily on the variety, but also on growing environment and cure technique. The destruction of chlorophyll eliminates the minty taste that is commonly associated with green homegrown.
There are several methods of curing, most of which were originally designed to cure large quantities of tobacco. Some of them can be modified by the home grower to use for small marijuana harvests as well as large harvests. The methods used to cure marijuana are the air, flue, sweat, sun, and water cures.

Air Curing
Air curing is a technique developed in the United States for curing pipe and cigar tobacco. It was originally done in specially constructed barns made with ventilator slats which could be sealed; a small shed or metal building can easily be adapted for this use. However, this method of curing works only when there is enough material to keep the air saturated with moisture.
Wires are strung across the barn, and the marijuana plants or plant parts are hung from them, using string, wire twists, or the crooks of branches. The plants material should be closely spaced, but there should be enough room between branches (a few inches) so that air circulates freely. The building is kept unventilated until all the material loses some chlorophyll (green colour). This loss occurs rapidly during warm sunny weather because heat builds up, which hastens the cure. In wet or overcast weather, the temperature in the chamber will be cooler, and the process will proceed more slowly. If these conditions last for more than a day or two, unwanted mould may grow on the plants. The best way to prevent mould from forming is to raise the temperature to 90F by using a heater.
After the leaves have lost their deep green and become pale, the ventilator or windows are opened slightly, so that the temperature and humidity are lowered and the curing process is slowed. The process then continues until all traces of chlorophyll are eliminated. The entire process may take six weeks. Then the ventilators are opened, and an exhaust fan installed if necessary, to dry the material to the point that it can be smoked but still is moist, that is, bends rather than crumbles or powders when rubbed between thumb and forefinger.

Flue Curing
Flue curing differs from air curing in that the process is speeded up by using an external source of heat, and the air circulation is more closely regulated. This method can be used with small quantities of material in a small, airtight curing box constructed for the purpose. Large quantities can be hung in a room or barn as described in Air Curing.
A simple way to control the temperature when curing or drying small amounts of marijuana is to place the material to be cured in a watertight box (or a bottle) with ventilation holes on the top. Place the box in a water-filled container, such as a pot, fish-tank, or bathtub. The curing box contains air and will float. The water surrounding the box is maintained at the correct temperature by means of a stove or hotplate, fish-tank or water-bed heater, or any inexpensive immersible heater. Temperature of the water is monitored.
With the marijuana loosely packed, maintain water temperature at 90 degrees. After several days, the green tissue turns a pale yellow-green or murky colour, indicating yellow or brown pigments. Then increase temperature, to about 100 degrees, until all traces of green disappear. Raise the temperature once again, this time to 115 degrees, until a full, ripe colour develops. Also increase ventilation at this time, so that the marijuana dries. Plants dried at high temperature tend to be brittle; so lower the temperature before drying is completed. This last phase of drying can be done at room temperature, out of the water bath. The whole process takes a week or less.
Marijuana cured by this technique turns a deep brown colour. Immature material may retain some chlorophyll and have a slight greenish cast. Taste is rich yet mild.

Sweat Curing
Sweat curing is the technique most widely used in Colombia. Long branches containing colas are layered in piles about 18 inches high and a minimum of two feet square, more often about ten by fifteen feet. Sweat curing actually incorporates the fermenting process. Within a few hours the leaves begin to heat up from the microbial action in the same way that a compost pile ferments. Then change in colour is very rapid; watch the pile carefully, so that it does not overheat and rot the colas. Each day unpack the piles, and remove the colas that have turned colour. Within four or five days, all the colas will have turned colour. They are then dried. One way to prevent rot while using this method is to place cotton sheets, rags, or paper towels between each double layer of colas. The towels absorb some of the moisture and slow down the process.
Sweat curing can be modified for use with as little marijuana as two large plants. Pack the marijuana tightly in a heavy paper sack (or several layers of paper bags), and place it in the sun. The light is converted to heat and helps support the sweat.
Another variation of the sweat process occurs when fresh undried marijuana is bricked. The bricks are placed in piles, and they cure while being transported.
A simple procedure for a slow sweat cure is to roll fresh marijuana in plastic bags. Each week, open the bag for about an hour to evaporate some water. In about six weeks, the ammonia smell will dissipate somewhat, and the grass should be dried. This cure works well with small quantities of mediocre grass, since it concentrates the material.

Sun Curing
A quick way to cure small quantities of marijuana os to loosely fill a plastic bag or glass jar, or place a layer between glass or plastic sheets, and expose the material to the sun. Within a few hours the sun begins to bleach it. Turn the marijuana every few hours, so that all parts are exposed to the sun. An even cure is achieved in one to two days {(see Plate 16)}. Some degradation of THC may occur using this method.

Water Cure
Unlike other curing methods, the water cure is performed after the marijuana is dried. Powder and small pieces are most often used, but the cure also works with whole colas. The material is piled loosely in a glass or ceramic pot which is filled with luke-warm water. (When hot water is used, some of the THC is released in oils, which escape and float to the top of the water.) Within a few hours many of the non-psychoactive water-soluble substances dissolve. An occasional gentle stirring speeds the process. The water is changed and the process repeated. Then the grass is dried again for smoking.
THC is not water-soluble; so it remains on the plant when it is soaked. By eliminating water-soluble substances (pigments, proteins, sugars, and some resins), which may make up 25 percent of the plant material by weight, this cure may increase the concentration of THC by up to a third.
Marijuana cured by this method has a dark, almost black colour, and looks twisted and curled, something like tea leaves. The water cure is frequently used to cure dried fan leaves and poor-quality grass.

Drying
Living marijuana leaves are 80 percent water; colas are about 70 percent water. Marijuana dried for smoking contains only eight to 10 percent water, or about 10 percent of the original amount. There are several methods used to evaporate water; these have little effect on potency, but can affect the taste, bouquet, and smoothness of the smoke. Generally, the slower the dry, the smoother the taste. Excess drying and drying methods that use heat will evaporate some of the volatile oils that give each grass its unique taste and aroma.
Grasses which are dried as part of the curing process usually have a smooth, mild taste, because of the elimination of chlorophyll and various proteins. Cured marijuana may also be a little sweeter than when first picked, because the curing converts some of the plant's starch to simple sugars.
Some grasses are tasty and smooth-smoking when they are dried without curing, especially fresh homegrown buds which retain their volatile oils and sugar. Many homegrowers have acquired a taste for "natural" uncured grass, with its minty chlorophyll flavour; such marijuana is dried directly after harvesting.

Slow Drying
Slow drying is probably the method most commonly used to dry marijuana. Because of the slowness of the dry, a slight cure takes place, eliminating the bite sometimes associated with quickly dried grass.
There are many variations of the technique, but most commonly whole plants or separated colas are suspended upside down from a drawn string or from pegs on a wall in a cool dark room, closet, or other enclosed space. A large number of plants may take a week or two to dry. The drying time for small numbers of plants can be increased (for a slight cure) by placing the plants in large, open paper sacks that have ventilation holes cut in their sides. The drying room should have no heavy drafts, but mould may form on the plants if the air is stagnant. If weather is rainy or the air humid, increase ventilation and watch for any mould. Plants should be dried quickly under moderate heat if any mould appears.
Many experienced growers prefer slow drying to curing. There is little chance of error with this method, and buds usually smoke smooth and develop a pliable consistency. Slow-dried ripe buds retain their delicious, sweet aroma and taste.

Fast Drying
The fast dry-method produces a harsher smoke than slow drying, but it is often the most convenient method to use. The plants are suspended in the same way as for slow drying, but the temperature in the drying area is increased to between 90 and 115 degrees, often by means of electric or gas heater. The drying area is kept well-ventilated with a fan. As the plants dry, they are removed from the drying area. By this method, plants in a tightly packed room can be dried in less than four days, but the exhaust will contain the deliciously pungent odour of drying marijuana.
Indoor growers often hang plants to dry over radiators or stream pipes. Leaves are dried by placing them on a tray over a radiator or on top of the light fixture.
Marijuana that is fast-dried retains its original green colour and minty taste.

Oven Drying
Oven drying is often used by gardeners to sample their crop. Small quantities of material can be quickly dried by being placed in a 150 to 200 oven for about 10 minutes. Larger quantities can be dried in trays that contain a single layer of material or in a dehydrator. Oven-dried and dehydrator-dried marijuana usually has a harsh taste and bite, and loses much of its bouquet. The method is often used to dry marijuana which has been cured and dried but is too moist to smoke, or to dry marijuana which is to be used for cooking or extractions. It is an adequate method for obtaining dry material for testing and emergencies, but the main harvest should not be dried in this way. Oven drying works best with leaves. When leaves are dried together with buds or shoots, remove the material from the oven periodically, to separate the faster-drying leaf material (before it burns) from the slower drying buds. One way to do this is to place all the material on a wire screen over a tray. Every few minutes rub the material across the screen. Dried material falls unto the tray and is removed from the oven. Repeat until all the material has dried.
Oven curing works well when closely watched. Dried marijuana that is left in the oven will lose potency quickly. Any time the marijuana begins to char, most of the potency will already have been lost. This should not be a problem unless you are careless, or allow the temperature to go above 200 degrees.

Sun Drying
Some growers dry their crops right in the field. There are many methods of sun drying. In Oregon, some growers break the main stem about two feet from the ground. The leaves and buds dry gradually, since they are still partly attached to the plant. Other growers spread burlap and cover it with plants left to dry. Fan leaves are left on the plants to protect the drying buds from the sun. The grass is manicured after drying. Growers in Arizona shade drying plants with cheesecloth.
Sun-dried marijuana usually has a taste similar to that of oven-dried. Often the sun bleaches it slightly but also destroy some of the delicate bouquet. Prolonged exposure to the sun will decrease potency, although there is no noticeable loss if drying is done quickly.

Dry Ice
Many homegrowers have written to us that the dry-ice cure increases the potency of marijuana considerably, and we would be remiss not to mention it.
Dry ice is frozen carbon dioxide. When it melts (sublimates), it turns from a solid directly into a gas. This gas absorbs some moisture from the frozen marijuana and partially dries it.
There are many variations of the dry-ice method. Fresh or partially dried material is usually used, although some enthusiasts claim that the cure also works with dried material. The marijuana is placed in a coffee can or similar container with a lid, along with at least an equal volume of dry ice. Puncture the lid so that the gas can escape as it evaporates. Place the can in a freezer to prolong the evaporation process. When the dry ice is gone, the grass is dried, but still moist.
Some growers claim that simply freezing the grass increases potency. They often freeze fan leaves or other less-potent material for a couple of months before smoking it. This is said to work only with fresh (wet or dried) grass.

Fermentation
When vegetation dries, the individual cells which maintained life processes die. But marijuana can still be conditioned by means of fermentation. Fermentation is the process in which microbes and plant enzymes break down complex chemicals into simpler ones, mainly starch and sugars into alcohol and simple acids. In the process chlorophyll is destroyed, giving the material a more ripened appearance. If the fermentation is stopped early, the marijuana has a sweeter taste because of the sugars which the ferment produced.
Fermentation occurs when the moisture content of the marijuana is raised above 15 percent and the temperature is above 60 degrees. The more tightly packed the material, that faster the ferment proceeds. The rate of ferment is controlled primarily by varying the moisture content, but each batch proceeds at its own rate because of differences between plants in nitrogen content. (Nitrogen is necessary to maintain fermenting bacteria.) The process is delicate; should the ferment proceed too rapidly, the marijuana may be converted to compost. Watch the fermentation closely. After the desired colour or flavour (from a dried sample) is reached, dry the grass quickly to stop the process.
During fermentation, flavourings can be added to give the marijuana a spicy aroma. Such spices as cinnamon, cloves, ginger, mace, sage, or vanilla are placed between the fermenting material. Orange, lemon, or lime peels are also used. About half an ounce of spice or four ounces of peel are used for each cubic foot of material to be fermented. The spices are wrapped in cloth sachets. The citrus peels are strung. They can be placed between the layers of marijuana.
There are two types of fermentations: self-generating and forced. They are best used with leaves or immature plants.

Self-Generating Fermentation
Self-generating fermentation proceeds rapidly only when there is enough material to make a heap at least one cubic yard large. When smaller quantities are used, too much of the heat generated by the bacteria is dissipated, so that the process is slow and is more properly considered aging.
Place the material in a large container or in a pile with a tarpaulin placed over it, and lightly spray it with a mister if it is dry. Let the pile heat up for a few days, and then break it down. If it is repacked, the marijuana will develop a dull matte appearance and lose its sugars. IF the process is allowed to proceed even further, the marijuana will disintegrate.

Forced Fermentation
Forced fermentation can be used with small quantities of material. It requires an enclose chamber in which heat and humidity can be regulated.
Pack the marijuana loosely in a kiln or other chamber, and raise the temperature to 135 degrees. Maintain humidity at 75 percent. Check the progress of the ferment periodically. Within a week the ferment should be completed. During this ferment there is a release of ammonia compounds, resulting in some foul odours, but upon completion of the ferment and drying, the marijuana should smoke sweet and mellow.
Storage
THC is degraded by both heat and light. Table 26 shows results of an experiment conducted at the University of Mississippi, in which marijuana was stored under varying temperature conditions171. These results indicate that marijuana stored at room temperature (72) or below, and in darkness for up to two years will lose only an insignificant amount of its original potency; whereas marijuana stored in darkness at 97 or above will lose almost all its potency within two years.
In another experiment,164 Fairbairn stored dried marijuana at different temperatures in both light and dark conditions. The samples in light were exposed to a north-facing windows (no direct sunlight). The results are shown in Table 27.
Fairbairn also performed an experiment to discover the effect of air on THC164. Freshly prepared Cannabis resin was stored as a loose powder, a compressed powder, and an unbroken lump for one year at 68 degrees F (about room temperature). Samples were stored under two conditions: in light and air, and in darkness and air. The results are shown in Table 28.
Fairbairn experimented further with pure cannabinoids and extracts of marijuana dissolved in petroleum ether, chloroform, and ethanol (alcohol)165. The results, in Tables 29 and 30, show that the THC and CBD in solution are much more unstable than when they are left in marijuana, especially if they are held by the plant in undamaged glands, where they are protected from exposure to air and, to some degree, light. Crude extracts seem more stable than highly refined cannabinoids, especially CBD, which is very unstable in refined solutions.
Extract makers and purchasers should limit the exposure of the solution to light and heat as well as to air. Oils and extracts should be kept refrigerated in opaque, sealed container. Notice that THC is almost completely degraded in a few weeks when it is held in solution and exposed to light. Red oil, hash oil, and honey oil must be stored in light-tight containers to preserve potency.
From the tables, you can see that light is the primary factor that causes decomposition of THC. The decomposition products are unknown, but are suspected to be polymers or resins. We also do not know whether the rate of decomposition would be faster in direct sunlight.
Air (oxygen) acts much more slowly to convert THC to CBN. Decomposition of THC to CBN is not significant unless temperatures are in the nineties or higher. However, such high temperatures can occur in grass that is packed before it is properly dried. The moisture that is left supports microbial activity, which heats the grass internally, as occurs during certain types of curing. Potency of cured grass is not lowered significantly when the cure is done properly and when the buds are left intact during the process.
The figures for powdered and compressed grass in Table 28 show that both light and air cause rapid decomposition when the resin is exposed through breaking of the resin glands. Intact resin glands appear to function well in storing the cannabinoids. For this reason, it is important to handle fresh and dried grass carefully, in order not to crush the material and thus break the glands, especially in the buds, which have a cover of raised resin glands. Most well-prepared marijuana will have intact, well-preserved buds.
The best place to store marijuana is in a dark container in a refrigerator or freezer. Cannabis should be stored uncleaned, so that the glands containing the THC are not damaged, since damage causes their precious contents to be exposed to light and air. Marijuana should be cleaned only when it is about to be smoked.
Many growers place a fresh lemon, orange, or lime peel in with each lid of stored grass. The peel helps to retain moisture, which keeps the buds pliable, and also gives the grass a pleasant bouquet.
Most growers take well-earned pride in the quality of the marijuana that they grow. By supplying yourself with an herb which may play an important role in your life, you gain a feeling of self-sufficiency that can be infectious.
Since your homegrown is well-tended and fresh, it has a sweet flavourful taste, far superior to that of commercial grass. And there need be no fear of contamination from herbicides, pesticides, adulterants, or other foreign matter. By growing your own, you come to the pleasant realisation that you are free from the vagaries and paranoia of the marijuana market - not to mention how little a home garden costs. All of these feeling can add up to a very heady experience.
In a time of quiet contemplation, you might also reflect on the experiences that brought you this wondrous herb from a tiny seed. There is a tradition of mutual nurture and support between humanity and this plant that goes back 10,000 years.