How Kief Screening Works
THC and other cannabin
How Kief Screening Works
THC and other cannabinoids and terpenes are concentrated in glands that cover many parts of the marijuana plant, but they are concentered in the upper leaves, flowers, and flower bracts of unfertilized female plants. They are also found on the seed covering and surrounding areas of pollinated plants. Screening cured plant material is one of the easiest ways to rescue these glands for use.
There are several different methods to prepare the plant material for processing and for screening or sifting kief. In countries close to the 30th parallel, such as Nepal, Afghanistan, and Lebanon, small amounts of kief have traditionally been made using a silk scarf stretched tightly over a bowl. Dried marijuana, frequently cured for as much as six months, is rubbed on the taut silk cloth. The cloth’s fine weave allows the small glands to pass through to the bowl, leaving the vegetative material on top. Silk scarves are still used in parts of the world, but the nylon or metal mesh screens used for printing (still often called silk screens) are more durable and come in a variety of dimensions and mesh sizes.
One of the simplest methods of making kief is by gently rubbing the plant material over a fine screen. The size of the openings in the screen determines which size glands and how much residual plant material will make it through. The vigor used in rubbing it on the screen has a profound effect on the quality of the final product. Different grades of kief are produced by varying the amount of time the material is sifted, the screen’s gauge, and the pressure used. Sifting the same material a few times yields more kief, but each sift results in a higher proportion of plant mixed with the glands. Kief color ranges from golden-white for the purest kief to a greenish gold. The greener it is, the more plant material it contains.
Kief or pollen-sifting boxes are good tools for making small amounts. They can be as simple as wooden stash boxes with a screen above a pullout drawer that catches the glands that fall off your weed in normal handling. Other boxes are made specifically to capture different grades of kief, separating the glands from the vegetation by shaking it. Over-vigorous shaking or rubbing is counterproductive because too much vegetation is collected, lowering the quality. Use cold material. Freezing makes it crisp so the glands break free easier.
Some larger sifters are automated much like a paint mixer, so you can add the material, flip a switch, and let the sifter do the work.
Compact DIY solutions are inexpensive and easy to make using screens used for printing T-shirts and posters. All you need is the proper screen, a frame to stretch it on, and a smooth hard surface such as glass or metal to collect the kief.
Printing screens made of nylon, polyester, or metal are available at art supply stores or online. In the United States mesh sizes are typically described in terms of the number of threads per inch (25.4 mm), so a higher number is a finer screen. Meshes range from around 40 to 400, with 110 and 156 being the most common for printing T-shirts. Screen mesh from fine to coarse can be purchased pre-stretched in aluminum or wood frames, or as rolls or sheets.
Preparing For Screening
Very little preparation or work is needed to make excellent kief. Kief making is so quick that small quantities can be sifted or sieved easily while trimming cured bud or preparing for another process.
Kief is best made from dry, well-cured, coarse marijuana. Many people like to salvage kief from trim that they might otherwise discard. The stems can be sorted out, but don’t have to be. The more bud bits you use, the better quality kief you’ll get.
For the best results, start with trim and leaf that is dry but not overly crisp. If it is too dry the vegetative material becomes brittle and can crumble into dust or powder that can pass through the screen along with the glands you’re trying to collect. Kief made from over-dried material contains more green matter, tastes more like chlorophyll, and is less potent. Similarly, densely pressed material or “brick” marijuana does not work as well for kief as loose material does.
When to Sieve
In the mountains of the Hindu Kush region, hash makers have traditionally waited for cold, dry weather to sift their kief. Curing is key to all fine marijuana products, so waiting for the cold is a way of making sure that the buds drying in open air are in a state of prime readiness. Cold also freezes the dry leaves and trim, making the tiny trichome stalks brittle. That lets the glands break free more easily. Less agitation or pressure to free the glands results in less vegetative material in the kief. As a practical benefit, keeping the glands intact also reduces the amount of resin clogging the screen, though this rarely happens, even in moderate temperatures.
As with overly dry marijuana, overly brittle, frozen vegetative material can become powder and pass through the screen. Moistening the material by airing it in a space with high humidity might help. Using a finer screen may be another solution. Having several sizes of screen mesh allows you to use the right one for the material and temperature.
To make pro-quality kief, the colder the plant material you start with, the better. Prepare the material by putting it in a freezer overnight.
There is no need to overthink the process. Remember, kief is simple. Kief of decent quality can be made in all weather conditions. Cool temperatures, around 15°C or lower, are best for working with marijuana. Low to moderate humidity is okay, and if the material is particularly dry, a little extra humidity can be helpful.
Manual screening is cost effective and no more labor intensive than sifting flour. It is possible to buy ready-made screens or kief boxes from many sources and in many sizes. The screen, usually wire mesh, comes framed and often includes a solid bottom drawer where the kief is collected. Most art supply stores sell plastic screens for printing that are already stretched on frames made of wood or aluminum.
Making your own screens or boxes requires no special skill. Frames to stretch screens over are easy to make or buy. Just decide how big you want it, and pick a screen size and material. Stainless steel mesh screen or “wire cloth” is sturdy, durable, and rarely needs cleaning. Nylon or polyester silk screen mesh is more flexible but should be replaced annually. The frames and silk screen materials are available at art supply stores.
If you build your own screen or have a screen without a tray, a piece of glass or mirror makes a good surface for catching the kief and gathering it up. Whatever you use, smoothness is the crucial quality of a catch tray, as the glands you’re collecting can be smaller than the diameter of a human hair. You don’t want to lose any to texture. A credit card, ID, business card, or other straight edge can be used to gather the filtered material into a pile.
Making Your Own Screen
- Thick wooden picture frame, or a frame constructed of wood at least 2.5 cm x 2.5 mm
- Wire cloth or silk screen mesh cut large enough to wrap around to the underside of the frame
- 1 cm wire tacks or staple gun
Cut the wire cloth or mesh to fit over the frame with 2–3 cm or more to spare on each side, depending on the thickness of the frame—the screen should wrap around the sides of the frame. For instance, if the wood frame is 38 cm x 15 cm, cut the wire cloth to 44 cm x 21 cm, which leaves about an extra 3 cm on each side.
Stretch the screen taut and fasten it securely using tacks or staples on one side, then pull it tight and secure the opposite end to the other side of the frame. Repeat with the other two sides.
The Screening Process
Place the collection tray under the screen. Start with a handful of trim, leaf, or small nugs, as you prefer. Leaf doesn’t require any preparation before rubbing but use a grinder to prepare the bud.
nce you’ve ground the bud, or if using the whole leaves, gently rub the material softly against the screen. A softer touch or action minimizes the amount of vegetative matter that passes through and keeps more of the glands intact. This first pass is the cleanest and most potent kief.
Connoisseurs sometimes use multiple screens progressing from coarser to finer mesh. In the first pass, they use a mesh with fewer than 100 strands per 25.4 mm. This first screening cleans out the bulk of the vegetative matter. The sifted material is collected and placed on a finer-mesh screen. Since the material has already been reduced to a coarse grind by the first screen, the second, finer screen only needs to be shaken or tapped lightly to create cleaner kief. The kief remaining on the second screen should be saved—for ingestion, capsules, tinctures, or salves. Screening with successively finer meshes yields different products and flavors.
Keep the first sift light and brief, up to a minute. This yields the finest grade of kief, but the yield is fairly low. The biggest, most mature glands are the first to break free and sift through. Only the first few minutes of screened material is pleasant smoking material.
The yield from the second sift is still potent but of considerably lower quality than the first. It is greener and has more of a taste of chlorophyll. After the first two sifts the material can be screened a third time for as long as 10 minutes and the resulting product can be used for ingestion or external purposes, or for further purification.
When screening by hand a soft touch and proper screen are important, as is maintaining the right environmental conditions. Experimentation is easy, low cost, and fun, so even the complete novice can figure out how to create top-quality kief with minimal fuss.
Even if it is not your preferred product, kief is so cheap and easy to screen in small amounts that everyone should try it. For those who appreciate its pure flavor or other uses enough to focus on producing larger quantities, a drum machine or industrial sifter may be a worthwhile investment. There are many kief sieves available, often marketed as pollen sifters.
If you have a lot of leaf and trim that you’d like to process for kief, you may soon find manual screening to be tiresome and inefficient. You’d not be the first. For high-volume kief making, simple drum machines automate much of the task. As a bonus, they typically gather a higher percentage of glands from the plant material than flat screening by hand.
The Pollinator is the original drum machine developed by Mila Jansen, a hash aficionado from the Netherlands who lived for years in the Hindu Kush region. Mila spent her fair share of time manually screening kief in cold weather. Luckily for the rest of us, Mila is an innovator.
One evening after a long, tedious day of screening, Mila was home doing laundry when the clothes dryer caught her attention. In a flash, she realized that the dryer was essentially doing the same thing she had been doing all day! Soon thereafter, she invented an electric-powered tumbler for her personal use. It would be a few years before it occurred to her that this machine might be marketable, but when it did, the Pollinator was the result.
The Pollinator is available in a few sizes to accommodate different needs. You just place the material to process inside and turn it on. The machine tosses it softly against a fine screen, around 130 strands per 25.4 mm. The amount of time it runs determines the quality of the kief collected. Presses and water hash equipment (like the Ice-O-Lator) are also available through the Pollinator Company.
Dry Ice Kief—The Manual Method
Perhaps the cheapest, simplest way to concentrate cannabinoids is also one of the newest. Since 2009, hash makers have been turning to dry ice—which is frozen carbon dioxide—to yield an impressive amount of kief. Dry ice is the fastest way to turn trash into gold. Manual dry ice sieving is very inexpensive to set up, results in very little mess or cleanup, and doesn’t involve explosive chemicals like BHO, or require expensive machinery.
One-Minute Dry Ice Kief is my favorite concentrate. It is very smooth and contains a lot of terpenes because it is made cold and not mixed with anything, even water, preserving the terpenes. It has very little vegetation so you are inhaling only gland products.
- Cannabis (28 grams, dry trim or fresh-frozen)
- Bubble Bags (durable 160- and 220-micron water bubble bags)
- 19-liter bucket
- Clean, sanitary surface area—at least four feet long
- Collection tool (such as a plastic scraper)
- Dry ice—1.4 kg, broken up into small pieces
Manual dry ice sieving uses the -76°C temperature of dry ice to freeze the waxy stalks of the trichomes, making them brittle enough to mechanically snap off during agitation. The snapped glands then fall through the 160- or 220-micron bag onto a surface and get collected.
First, designate a clean, sanitary, indoor space with a table with a clean surface. Sanitary conditions are important. You don’t want to find dog hair or other contaminants in the final product. Set up a large table in the clean room, and cover it with some parchment paper.
Place trim or ground bud in the bucket. Add dry ice. Tightly affix the 160-micron bubble bag over the top of the bucket using large rubber bands so that when you eventually turn the bucket upside down, the dry ice and trim fall onto the screen.
Pick up the bucket and gently shake to help distribute the cold. After a minute, turn the bucket upside down and hold it over the parchment paper. The dry ice and trim fall to the bottom of the bag.
Lightly shake the dry ice and trim mix up and down, moving longitudinally along the surface of the table so the falling kief creates a trail two to three meters long.
As you do this the kief dust will fall down from the bag onto the paper, amid little puffs of evaporating carbon dioxide. Keep shaking for 30 seconds to sieve the trichomes through the filter. You will notice that the first glands are a pale golden-yellow and that as the process continues the trail of glands gets greener, because more vegetative material is in the mix. The first material to fall, the golden glands, is the highest quality.
Use a scraper to collect the kief, which should smell phenomenal, and store it in a clean, glass jar.
Repeat the process using the 220-micron bag, and collect the kief.
One ounce of dried sugar leaf trim yields about four grams of kief at 160 microns, and six more lower-grade grams of kief at 220 microns.
- Dry ice sieving kief sends weed dust everywhere unless the bucket bottom, where the screen is, is kept close to the table surface.
- Avoid working in areas with breezes.
- Use thinner chunks of dry ice and less agitation for purer kief.
- Use quality nylon mesh bubble bags. Plastic mesh bags degrade under the brutal cold of the dry ice.
- If you are making your own device, use stainless steel mesh rather than nylon. The nylon wears and chips when it’s frozen by the dry ice. Stainless steel lasts indefinitely.
- You can use either dried or fresh-frozen trim. Both kief out nicely, and the fresh-frozen contains more terpenes.
Dry Ice Kief—The Machine Method
Moving to a larger scale, Friendly Farms of California makes a portable extraction machine for dry ice sieving cannabis.
- 1 kg of fresh or numerous grams of dry trim
- Extraction Contraption cone with bracket
- Portable electric cement mixer
- 4.5 kg of dry ice
- Hydrogen peroxide
- Cold-resistant gloves
This method is very simple. Fill the mixer with 1 kg of any mix of dry leaf/trim/ground buds and 4.5 kg of dry ice cubes or small pieces. Affix the Extraction Contraption cone with a bracket.
Turn on and angle the mixer so the cone faces down. The device will turn, mixing the dry ice and trim. The Extraction Contraption comes with screens at 75 through 150 microns to allow the glands to pass through while catching everything else.
After one minute, turn off the mixer. Remove the catcher, and open it up. The fine dry powder inside may be the finest kief you have encountered. This is the notorious One-Minute Dry Ice Kief. It contains almost no vegetation, only the pure glands. It glows pale yellow. Remove the kief just extracted.
Return the cone to the extractor several times for two- and three-minute hash. By the fourth cycle the hash is seriously green and no longer a pleasurable smoke. It can be used for further extractions and cooking. After turning for 10 minutes almost all the glands have been removed.
This method extracts THC from 3% leaf to create 30% kief. It yields between 60 to 112 grams of kief per pound of material. It has one of the easiest cleanups, since dry ice evaporates into the air and leaves nothing wet behind. A wipe down is usually all that is necessary. If convenient extract the kief in a greenhouse or grow room during the lit period. The plants will use the evaporating CO2.
The Extraction Contraption pairs with a still that uses grain alcohol solvent to create more refined, dabable products.
- Different strains yield kief with slightly different odors, flavors, tastes, and colors.
- This method works with dry trim, but works best with fresh sugar leaf.
- Yield and quality remain inversely related. Slight agitation and narrow filtering result in the purest kief, but yield less. Lots of agitation and a wide screen results in the most yield, but the resulting kief has more impurities and is less potent.