Dry Sift Cannabis for Pressing: Mesh, Temp, and Bag Sizes
Dry sift presses into rosin at 170 to 200 F in a 25 to 37 micron bag. Grade, moisture, load size, and pressure set the yield.
Dry sift weed screens separate resin heads from plant material. Mesh openings are measured in microns. A head on a capitate-stalked trichome measures about 50 to 120 microns across. Leaf and stem fragments measure larger. Screen size decides what passes and what stays on top. A set of 160, 120, 90 and 73 micron screens covers most home and small commercial work.
Dry Sift Cannabis for Pressing: Mesh, Temp, and Bag Sizes
What Dry Sift Screens Do
Resin heads sit on stalks. The stalk attaches the head to the plant surface. When plant material moves over a screen, brittle heads break off and fall through the openings. Stalks, leaf edges and stem bits stay on the screen. The result is a graded powder called dry sift. Kief is the ungraded powder that collects in a grinder. Dry sift is kief that has passed through one or more screens.
Mesh Sizes and What They Catch
- 220 microns: work screen. Holds buds and trim, passes everything else.
- 160 microns: first grade. High weight, more plant matter.
- 120 microns: middle grade. Mix of heads and small leaf bits.
- 90 microns: clean heads. Little plant matter.
- 73 microns: high grade. Low weight.
- 45 microns: fine heads and broken heads. Used for rosin.
Sellers label mesh in lines per inch (LPI) or in microns. The two numbers do not convert with one formula. Thread diameter changes the opening size. Trust the micron figure when a seller lists both.
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Screen Materials and Frames
Stainless steel mesh holds its shape and cleans with isopropyl alcohol. Silk and nylon mesh cost less and stretch over time. Frame sizes run 8x8, 12x12 and 16x16 inches. A 12 inch frame fits a 5 gallon bucket rim. Wood frames absorb resin and are hard to clean. Aluminum and stainless frames wipe clean.
Room Conditions
Resin turns soft and sticky above 70 degrees F. Soft heads smear on the screen and trap plant matter. Work at 50 to 60 degrees F. Humidity at 40 percent RH or lower keeps heads from clumping. A cold room and low humidity give a cleaner first pass than any technique change.
Method
- Dry the material. Trim and buds need 10 to 14 days at 60 to 70 degrees F and 55 to 62 percent RH.
- Freeze the material for 1 to 2 hours. Cold resin breaks off the stalk instead of bending.
- Stack the screens. Coarse on top, fine on the bottom.
- Place 30 to 60 grams of material on the top screen. More weight slows the pass.
- Move the material with a plastic card. Use slow strokes and light pressure. Heavy pressure pushes leaf pieces through.
- Collect from each screen with a separate card. Keep the grades apart.
- Clean the final product. Run it on a 73 or 45 micron screen. Static tech uses a charged surface to pull resin heads from plant matter. Test static on small amounts first.
Yields and Grades
Dry sift returns 5 to 20 percent of starting weight. Cultivar, trichome density and dryness set the number. A first pass over 160 microns gives the most weight and the most plant matter. The 73 to 90 micron range gives less weight and a cleaner product. Clean dry sift tests at 40 to 70 percent THC. Full melt, which leaves no residue, needs heads that pass a 90 micron screen. Rosin makers press 160 micron sift for yield and 73 micron sift for color.
Storage
Store sift in glass, in the dark, at 60 to 65 degrees F. Air and light convert THC to CBN over months. A sealed jar with low headspace slows the change.