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Dry Sieving Summary:

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Dry Sieving Summary:


Dry sieving is one of the oldest methods of harvesting the trichomes from plant material and produces some of the tastiest hash, in that it retains more of the plant turpenoids and flavoids than ice water extraction.


Especially of the kif is used loose and un-pressed shortly after extraction. Pressing into blocks was in fact developed to preserve the kif for storage and travel, by limiting how much of its surface was exposed to the air.


Dry sieving was arguably the second or third method of trichome collection developed in the fertile crescent and coincided with the arrival of fine thread count cloth from China.


The oldest method of hash production is thought to be hand pressed Charas, which involves rubbing the fresh green flower heads between your hands until they are coated with sticky resin and then rubbing your hands together until the resin balls up.


Some argue that dry sieving was the second, but I wonder why just shaking the dried plant over a collection surface and scraping up what falls off, would not have occurred next.


What ever the sequence, in its simplest form, dry sieving involves curing the material and shaking and raking it in a mesh sieve. The sieve opening size is such, that mature trichome heads are the largest particle that will fall through them, usually in the range of 150 microns.


The kif can be used as is at that point, but if further refinement is desired, the kif that is collected in the first sieving step, can be re-sieved using a different mesh size to drop out the particles smaller than the mature trichome heads, as well as into different grades of kif .


Typically the bottom end of the mature trichome head size is in the neighborhood of 73 microns and the material passing the 150 micron sieve and caught on the 73 micron sieve, might also be sieved at ~110/90 micron to produce three grades.


The highest grade in this case would normally be the 73 micron sieve and the next highest the 110/90 micron sieve.


The lowest is usually the material that passes the 73 micron filter, most often immature heads and fine plant material. It isn't totally worthless however, so a final sieve at around 25 micron


Experimenting is necessary to optimize the collection from different strains, as trichome head size varies some by strain. A hand held microscope is your best friend when dry sieving, because it will tell you two critical things.


The first is what you have left yet to collect, and the other is how much plant material you are also collecting in the mix. It is not possible to collect all of the trichomes without starting to also pick up more and more plant material, so we typically stop collecting when we have about 10% kif by weight and can see excessive green material starting to show up in the mix.


We will typically extract the balance of the resin from the plant material using solvents, oils, or glycerin, so it doesn't go to waste.


Earlier I noted that a hand held sieve is the simplest method of dry sieving, but there are several higher production methods that bear discussion. The more common method is the use of a tumbler with a mesh drum. The plant material is placed in the drum and it is rotated over a collection surface. Often marbles are added to help fracture of the trichomes, but also fracture plant material, so are a mixed blessing.


As it is rotated, the fractured trichomes fall through the mesh drum onto the collection surface below, while the plant material is retained in the drum.


They are simple to construct and a typical DIY home size tumbler might be in the 8" diameter range, with 150 micron stainless mesh or monofilament silkscreen drum cover, turning in the neighborhood of 25 to 30 rpm's.


Though I designed numerous chemical milling tumblers in industry, I haven't experimented with kif tumblers personally. Brother Southpaww uses one to good advantage however and has found his best product cutoff, with low plant material contamination at about 20 minutes of tumbling.


Another method, less commonly used but which is significantly faster, is using vibration. We use such a vibratory device instead of a tumbler, which we have named the Grinning Reaper and I have previously posted a thread under that name giving more specifics.


Basically it works by sandwiching the plant material between a 130 micron stainless screen and a 1" thick nylon plate with a vibrating palm sander attached. We process the material in a cured and frozen state, to make it more brittle and we can collect 10% kif by weight in about 3 to 5 minutes.


Fast is good, but the easiest method that I have found to collect kif is to use a harvest box when they are preparing cured bud. A harvest box has a tray in it for breaking up buds when manicuring or breaking up for smoking or vaporizing. The bottom of that tray is a mesh screen and it sets on a collection surface.


I use the tray to conduct my normal activities with sweet Mary, and periodically lift out the tray and harvest the trichomes that have fallen through the screen. You would be amazed at how fast it builds up, which tells you how much you have been losing without knowing it.


I made my own harvest box using nothing more complicated than a table saw. I also used a glass cutter, an electric drill, tin snips, a screw driver, clamps, and glue.


I also made my own sieving frames, using a table saw, router, drill, and screw driver. I made them to accept either stainless mesh, or silk screen. The silk screen is rolled into place using 1/8" screen door spline, and both the spline or the stainless mesh is held in place with screws and clamping strips.


The different mesh frames nest for storage, so you can set up as many as you need to optimally process the different strains that you keep on hand.


I have already posted information on the Grinning Reaper and will follow through with separate posts on building sieving frames, as well as a harvest box under those titles.


Here are some pictures of the different DIY equipment we've built to date: The two tumblers are just examples of others designs.

Stretched frame bottom.jpg

Stretched frame top.jpg

Kief frame stack system.jpg

Harvest box-1.jpg

Grinning reaper 001.JPG

Grinning reaper 3 minute run (1).jpg



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