What is hash and how do I make it?

This article is intended to be a resource for those new to hash making, 
and is a general survey of the techniques that can be used.

What is hash?

The drug produced by the cannabis plant is principally contained in multi-cellular structures on the surfaces of the leaves and flower parts called stalked capitate trichomes, or multicellular glandular hairs. These structures are shaped like water towers or mushrooms, a ball on top off a stalk. Light glistening off the surface of these translucent structures is what causes the "frosted" appearance of plant parts populated with such glands. The ball structure, or gland head, consists of a number of radially arranged cells which secrete cannabinoid containing oils. The oils collect beneath a waxy cuticle, which occasionally bursts, releasing the oil to form a sticky resin as it dries. This resin may make up the cuticle or the cuticle may be some other substance, the truth is apparently not known. The gland head structure contains the highest concentration of the drug THC, followed by the stalks. The tissues of the plant supposedly contain a small amount of cannabinoids, but it is minimal in my experience, or at least there is little THC content.

The stalked capitate glands are not the only surface structure on cannabis plants. Multicellular sessile or bulbous glands hug the surfaces of some leaves, and are said to contain cannabinoids. In my experience they contribute little to the drug content of the plant. Some authors apparently believe these structures to be juvenile or stunted stalked trichomes. Cystolith hairs are blunt, pointed objects which contain calcium carbonate crystals. They look like faceted traffic cones, and do not have a ball on top. Finally, the plant also produces unicellular hairs, which indeed do look like small hairs. Cystolith glands and unicellular hairs do not produce drug chemicals.

Cannabinoids are chemicals apparently unique to cannabis, consisting of THC, CBN and CBD, and a set of relatives with similar effects, THCV, CBV and CBDV. Many plants contain both sets of chemicals, and in common practice only the first set of abbreviations are used. THC is responsible for the "high" the plant produces, and there are several different versions of THC from different plants. CBN is said to increase the THC effect slightly, and CBD actually blocks the THC effect. CBD can be converted into THC by treating extracted oil with sulfuric acid, a step in the oil trade called "isomerization".

Hash is made by knocking the trichomes off the surface of the plant, by mechanical action typically, and by pressing the glands together into a ball or cake. Depending on the method used, the hash may consist of gland heads and stalks and various contaminants, such as the elements mentioned above, and small bits and pieces of plant tissue. Hash made purely from gland heads is very strong and compresses to a hard plastic-like lump with hand pressure. Hash with a lot of contaminants may require heat and pressure to compact.

The effect of smoking hash can differ from the parent plant, as the heads of the stalked glands may contain more THC in comparison to the side chemicals than the stalks and the tissues of the plant. Hash made only from the heads of the stalked glands is very potent, and can create an uplifting high similar to a vaporizer hit, though deeper and more persistent. As more stalks are added to the hash, the character of the high changes in various ways, though typically good hash has a strong initial rush and a mild, soft letdown. I have found that the varietal character of the parent plants is diminished in hash. The cystolith and hair trichomes add nothing to the high, but may add to the flavor. Essential oils are distributed throughout the plant, making up about 10% of the stalked glands by weight. The essential oil content of the contaminants is apparently not known.


Methods of small scale hash production

We'll ignore the hash making methods used in cannabis growing countries for the commercial markets and focus solely on the home grower. There are three methods in common use.

The first is flat screening, typically using a silk screen frame with fine plastic fabric. Fine steel screens are also used in flat screening. The method involves rubbing cannabis trim across the surface of the screen, the glands and other contaminants dropping through the screen to be collected on a surface like a piece of glass. A flat screen can also be used with an electric motor rigged to produce a back and forth or vibrating motion.

The second method also uses screen, but in a rotating drum, typically motorized using a rotisserie motor or the like. A rotating machine takes less skill to use, substituting time for pressure in flat screening. A drum machine can remove nearly all the glands without depositing any plant tissue. That would be very difficult with a flat screen.

Finally, the glands can also be knocked off the plant by agitating the material in ice water. The glands sink to the bottom of the mixture and can be sieved, dried and pressed together. While this method requires only a blender and a coffee filter, it seems to produce more contaminants than screening, and the output can't be controlled as well, if at all.

Before discussing each method in more detail, let's talk about the preparation of the raw materials.


Preparing "skuff"

Skuff, or "shake" or bud trim, is leaves and undersized flower parts that are trimmed off cannabis flowers or buds. Unless glands can be seen on the surface of the leaves, they should not be collected as skuff, as all they can provide to the hash is contaminants. Sometimes a leaf will have a frosted appearance, but on closer examination the structures on the leaf turn out to consist principally of hairs, common on the stalks of fan leaves. The first tool needed in making hash is a magnifying glass to observe the plant surfaces. I find that a 16x "loupe" is sufficient for this purpose. Inexpensive 30x plastic scopes can apparently be found in toy stores.

In order to be ready for smoking, the THC oil must be dried. At the same time in order to allow mechanical skuffing, the plant material must also be dried. It is not necessary that the skuff be "cured" as buds are, because the vegetable material will not be used in any way. But I have found that the skuff needs to be thoroughly dried over a long period of time, at least a month, though I prefer two. Skuff processed before that time is not as potent as it should be, and the resulting hash seems never to dry properly to gain the potency back.

I have read many times that skuffing should be done in a cold, dry atmosphere and that the skuff itself should be crispy dry. For small scale skuffing, that is not only incorrect, it is also counter-productive, as it accelerates the expression of contaminants from the skuff. I used to believe in cold and dry until oldtimer1 taught me different; try it and see for yourself. The product of the first 20 minutes of skuffing on a drum machine should only be the heads of stalked capitate glands. Skuffing done in cold, dry conditions will prematurely kick out a lot of cystolith mineral trichomes. I recommend skuffing at low room temperature, in the 60's say, and at normal humidity, although I've made excellent hash in somewhat colder and hotter conditions.

The skuff should also not be physically altered. A drum machine will remove nearly all the drug potential from the plant, regardless of the shape and size of the leaf parts. With large leaf pieces, like those produced by the buds of certain strains, a mechanical aid can be introduced into the machine, like a rubber ball. The ball will gently press the leaf pieces to the screen over time. Crunching up the skuff will only serve to introduce vegetable contaminants into the hash, and will release cystolith and unicellular hairs into the first product from the skuffing, a product which should be the most pure. Be gentle with the skuff.

Flat screening

Flat screens can be made from commercial steel fabric, usually available by special order in printing supply shops, or from plastic silk screen fabric. Fortunately, printing supply shops sell stacks of pre-made plastic screens in wood frames for a modest price, typically $15-25, depending on the size. Because the grade of the hash from a flat screen depends on the vigor of the handling, screens with smaller holes are better, in the range of 110 lines per inch to 137 at the high end. A 125 "mesh" frame is a good compromise. The silk screen material is attached by glue to the bottom of the wood frame, leaving a well on top with the wood pieces forming the sides.

Making good hash from flat screens depends on a lot of personal involvement. The method is simple. The frame is placed over a collection surface, like a sheet of glass or a mirror. I like to attach small wooden blocks to the bottom of the screen frame so that it can be used right side up, with the flat side of the frame on the bottom. That way the skuff is held within the walls of the frame as it is skuffed. The skuff is placed in the frame and is gently pushed back and forth over the screen with a pusher, like a credit card.

Making the best grade of hash can be done by applying almost no pressure to the skuff as it is moved around on the screen. There's no way that a flat screen can produce as much of the top product as a drum machine, since a lot of the capitate glands will not be in contact with the screen unless pushed into it. The pressure of the tumbling skuff accomplishes that in a gentle fashion in a drum machine, but extra pressure applied by hand will cause contaminants to be expressed in flat screening.

Additional pressure on the skuff is best done by tilting the plastic pusher card into the skuff as it is moved across the screen. But there is a limit to how much pressure can be applied before vegetable material starts to break off and be passed through the screen. Some vegetable material is acceptable in the lowest grades of hash, but too much pressure will produce a light green product that does not provide the expansive rush expected from hash.

It is difficult, if possible, to extract all the glands from the skuff by flat screening. I've found that the exhausted flat-screen skuff is still quite potent, and is welcome by smokers who remember the good old days when you could sit and smoke Mexican grass for hours on end, a social event lost in modern times due to the uniform high potency of home-grown pot.

Although flat skuffing is not as productive or as easy to control as a drum machine, it brings gland hash within the range of anyone with a few dollars and some bud trim.


Drum machines

A drum machine tumbles the skuff inside of a wheel with fabric attached to the rim, like a squirrel cage. The key to the drum machine is the slow speed it operates at. Time replaces the pressure of flat screening, the longer the run, the more contaminants. But proper drum screening never introduces vegetable material into the hash, as it never handles the skuff vigorously enough to crumble the leaves. A drum machine can gently strip nearly all the drug containing glands from plant material.

Drum machines can be purchased from at least one supplier in Holland who calls their product the "Pollinator". The Pollinator may be a nice machine, but the price is very high considering how simple the machine is. A home-built machine can easily be made for a few dollars by anyone with a reasonable degree of home handyman skills, which is just about a given for cannabis growers. Here's a link to an article I wrote that describes how I built my machine, and some pictures:


Here are the plans with photos:

• The article describes the method for using a drum machine, and I'll extract some of that material here: