Question about grits

E

ecfc

Joined
Jul 2, 2012
Messages
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I was wondering if somebody could tell me in microns the sand paper that I have, I don't know how to translate the grits from different grit measurement systems into microns:

p400

I have 600 grit paper marked a99 and sic and fb

c1200

c2000

I tried to use the table of grits that somebody posted but I couldn't find all of the ones that I have on it and was wondering if one of you guys could just tell me. Thanks in advance (why can't we just measure grit all in the same system.)
 
If I were guessing (and I am, as these things are always somewhat ambiguous), the 'p400' and 'p600' designations likely refer to the FEPA-P grit standard, and the 'c1200' and 'c2000' designations might refer to the CAMI standard. The other '600' is likely in one or the other ballpark. These standards are indexed in the The Grand Unified Grit Chart sticky, posted by Komitadjie at the top of the Maint forum page.

P400 = 36 micron
P600 = 26 micron

C600 = 16 micron
C1200 = 6.5 micron
C2000 = 1 micron

Edited to add:
The more I read about CAMI and FEPA standards, the more I see a pattern suggesting that the CAMI standard is much looser for a given grit. Apparently, it allows a wider range of particle sizes at a stated grit size. The FEPA standard is apparently stricter, meaning a much tighter tolerance for particle size, at a stated grit. This implies a higher quality and better predictability in performance, for the FEPA-graded sandpaper.

CAMI = Coated Abrasives Manufacturers Institute
FEPA = Federation of European Producers Association
 
Last edited:
ecfc said:
Thank you a lot :) Do you know where I could get something with a finer grit?
Click to expand...

I'm not super-familiar with abrasives, but here's what I've heard about (be sure to ask others too!):

(1) Most easily-available sandpapers come in grit sizes up to about 2500.
(2) There are finer sand papers, but a little harder to find. One standard example is 3M Micro Abrasive Films (3M Micro-Lapping Film, 3M Micro-finishing Film). You can find a description here:
http://www.toolsforworkingwood.com/...de=toolstore&nextpage=/extra/lappingfilm.html
(3) Beyond sandpaper, there are various Japanese waterstones which go to very fine grits. For example, Shapton, Chosera, King, etc.
(4) If you are willing to try stropping, then there are many abrasives which go down to 0.5 or even 0.05 microns. There are many diamond, cubic-boron-nitride (CBN), boron-carbide (BC),chromium oxice, aluminum-oxide powders compounds, and you can find them as sprays, suspensions, and pastes.
(5) There are some super-fine sharpening stones which are not waterstones. For example, Spyderco makes an "ultrafine" ceramic stone, and DMT makes an "extra-extra-fine" diamond stone. I've head that some Arkansas stones get very fine, but I don't know anything at all about their grit sizes.

The grit-size for the Spyderco "ultra fine" stones is kind of complicated; no one knows how to give it a grit rating. Sal, of Spyderco, has said so himself in the following discussion:
http://www.spyderco.com/forums/showthread.php?31188-Ceramic-benchstones-compared-to-DMT-extra-fine

Yuzuha posted some microscope photos related to the Spyderco Ultra-Fine stones in a fascinating thread on www.FoodieForms.com. The photos in the original thread are broken links, but yuzuha sent us the original photos and we reconstructed her post here (with her permission):
http://www.bladeforums.com/forums/s...lose-look-at-steeling?p=10887400#post10887400

Generally speaking, grit ratings are very complicated because one is trying to summarize a distribution of particle sizes with a single number. And that doesn't even account for particles breaking down into smaller particles (friability), the shape or particles, or how hard they are. But if you are curious, I posted some discussion about it here, in one of Komitadjie's threads for his Grand Unified Grit Chart:
http://www.knifeforums.com/forums/showpost.php?post/2387804/
http://www.knifeforums.com/forums/showpost.php?post/2390582/
http://www.knifeforums.com/forums/showpost.php?post/2393686/

If you find out more about abrasives, either technical material or just experience, then please post about it. :)

Sincerely,
--Lagrangian
 
ACE hardware is a good source for 180 through 1500 grit wet-dry paper, "gator-grit" brand I think. The auto parts stores will carry 1000/2000/2500 grit, but I don't recall them having much for the lower grits. Home Depot & Lowe's have poor selections for wet-dry paper. If you've got one of those wholesale tools stores nearby, they may have a good selection.
 
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