Grit Table / standards / Reference scale

The yardstick

The reference scale 参考刻度

JIS R6001, fitted across its range, as one yardstick

One scale to read every product against. The reference scale is JIS R6001, which spans the widest grit range that sharpening stones use (#240 to #8000), fitted between its grades and extended past its ends by continuing JIS's own trend, so any grit number maps to a micron. The real JIS rungs (#240 to #8000) are firm; the extended rungs (coarser than #240, finer than #8000) are our extrapolation and uncertain. The extended fine numbers land far below the maker numbers (#16000 here is 0.35 micron, where makers call it about 0.9), which is the point: maker ultra-fine grits run coarser than an extended JIS would put them.

Particle sizemicrons, log

1005030201053210.50.3

coarserfiner

inkmeasured or standardmaker figureour estimate

shapeknown distributionpoint, spread unknown

#150Our estimate

reference

96.3 µm

Extrapolated below JIS R6001 #240, continuing the coarse end-trend

#220Our estimate

reference

62.8 µm

Extrapolated below JIS R6001 #240, continuing the coarse end-trend

#240Standard-defined

reference

57 µm

JIS R6001 median.

#320Standard-defined

reference

40 µm

JIS R6001 median.

#400Standard-defined

reference

30 µm

JIS R6001 median.

#600Standard-defined

reference

20 µm

JIS R6001 median.

#800Standard-defined

reference

14 µm

JIS R6001 median.

#1000Standard-defined

reference

11.5 µm

JIS R6001 median.

#1200Standard-defined

reference

9.5 µm

JIS R6001 median.

#1500Standard-defined

reference

8 µm

JIS R6001 median.

#2000Standard-defined

reference

6.7 µm

JIS R6001 median.

#3000Standard-defined

reference

4 µm

JIS R6001 median.

#4000Standard-defined

reference

3 µm

JIS R6001 median.

#5000Our estimate

reference

2.4 µm

Interpolated between JIS R6001 #4000 and #6000 (log-log)

#6000Standard-defined

reference

2 µm

JIS R6001 median.

#8000Standard-defined

reference

1.2 µm

JIS R6001 median.

#10000Our estimate

reference

0.81 µm

Extrapolated past JIS R6001 #8000, continuing the fine end-trend (uncertain)

#12000Our estimate

reference

0.58 µm

Extrapolated past JIS R6001 #8000, continuing the fine end-trend (uncertain)

#16000Our estimate

reference

0.35 µm

Extrapolated past #8000 (uncertain; makers call their #16000 about 0.9 um)

#20000Our estimate

reference

0.24 µm

Extrapolated past JIS R6001 #8000, continuing the fine end-trend (uncertain)

#30000Our estimate

reference

0.11 µm

Extrapolated past #8000 (uncertain; makers call their #30000 about 0.5 um)