Hi,
I bought sieving mesh at these sizes Approximate size 2mm, 5mm, 7mm
Are these the substrate size or do i need to find the diagonal length of those sizes above which are square sizes?
Little bit confused thanks
Hi,
I think those will work just fine. Whatever stays between your 2 and 7mm, thatâs your main component. Particle size greater than 7mm, is used for aeriation (bottom) layer. Soil and dust that will come off from 2mm mesh, can be thrown away. I keep it for cuttings, muck, or other small-pot plants, but I try to remove fines (=dust).
The soil particle sizes suggested from Mirai are slightly different, because theyâre given in fragments of inches: 1/4" equals 6.35mm, and 1/16" equals to 1.59mm. Honestly, I donât think that this â0.5mm deviation can have any real impact.
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So here is the mesh sieve sizes
Iâm repotting my maple soon and will use the 3mm (300mm sieve set) Will the 3mm not be bigger as the diagonal is bigger than the 3mm sides.
Most sieves are made from wire mesh with nominally square holes. The size can be specified several different ways. In the United States the most common method is to specify the number of wires per inch - 4 mesh has 4 wires per inch. The wires take up some of the space so the openings will be smaller than 1/4 inch depending upon the diameter of the wire. In addition, the wires are normally woven so they go up and down over and under the perpendicular wires so the holes are not completely square.
The sieve will stop particles that have two dimensions that are larger than the hole and a few particles where only one dimension is larger and a second is close. Vigorous shaking with only a layer or two of particles on the sieve will minimize the later. The sieve may or may not stop long, thin particles. For example, when sieving soil for reuse I often get pine needles that much longer than the sieve opening going through.
In summary, I donât think the exact sizes of the particles really matters. The goal is to use a sieved soil where we have removed the large particles that wonât hold enough water and the very small particles are hold too much water. Ryan calls these extremes 1/4 inch and 1/16 inch and I am betting that he is using 4, 8, and 16 mesh screens rather than screens with 1/4, 1/8, and 1/16" openings.
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So its never going to be perfect and its acceptable to use the 3mm on the sieve for 3mm particle size.
I do have another question maybe stupid - If i want to use 3mm particle size do i need to sift it with a 4mm mesh then the 3mm correct?
I use 3, 4, 8, and 16 mesh sieves to screen my materials. I designate them as 9, 6, 3, and 1 mm on my storage containers (the SI units are close enough and more concise to write). I only use the 6-9 mm material for the aeration layer in bigger pots. I use a combination of the 1-3 and 3-6 mm for species and pot sizes where Rayn would say âleave the 1/16 inch inâ. I asked Mirai if they also separate using the 8 mesh screen (3 mm) or if they simply use the 4 and 16 mesh screens of â1/16â in" material. The answer was unclear.
In summary, I donât think you need to screen as tightly as -4mm/+3mm, but I believe you need get rid of the way oversized particles just like we get rid of the very fine particles. We want a soil mix which has lots of small gaps between the particles that are not clogged by small particles.
A quick note is that when making particle mixtures to maximize the packing density (what we donât want in bonsai) the general rule of thumb is to use size ratios of about 7 to 1, i.e. 1 mm particles and 7 mm particles.
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