Sandpaper Grit Sizes

Maybe I'm the last one on the planet to become aware of it, but there's two radically different standards for determining the coarseness/fineness of sandpapers. (There's actually more than two, but two's enough for now).

These are the CAMI (American) and FEPA (European) standards, and the silicon carbide wet-or-dry sandpaper a lot of us use in the U.S.A. is switching over to the FEPA system. So what's the change mean?

There's not much difference down to about grit number 220, but the two systems get farther & farther apart as the grits get finer & finer than 220. As an example, our good old familiar American 1000 grit (CAMI grit 1000) is equivalent to FEPA grit 2000 - designated on the sheet as "P2000"!

If you're like me with a lot of the older CAMI-designated papers, getting replacements can be kind of zooey because it's geting hard to find the older stuff. Here's a real busy chart comparing the CAMI & FEPA systems: http://www.evenfallstudios.com/metro...mparisons.html

Ain't change just wonderful? :rolleyes:

Regards

Thanks for the info niemi24s; We all certainly use a lot of paper building pistols...looking for that special look! The big problem is my memory though. My mind is like a full computer hard drive...I can remember anything new but I have to forget something to put the new stuff on the drive... :lm:

I stumbled across the difference quite by accident. At the only two places in my little town that have wet-or-dry sandpapers, over the years I'd stocked up on grits from 150 to 1500. Among them I had 400, 600, 1000 and 1200 but thought it'd be handy to have a few sheets of something between 600 & 1000 - if there was anything.

Was happy as a clam when I found some '800' until I got it home and noticed it felt rougher than my 600 - instead of finer! Then I noticed it actually was labelled P800 (and there's no P weight paper) on the back of the sheets and my sanpaper world was turned upside down!!

Turns out my 800 grit, being actually P800 (FEPA) grit, was effectively about 450 (CAMI) grit!

And the tricky part is I've seen 5 sheet packages of wet-or-dry from 3M labelled 400 on the package but the sheets in the package are labelled P400, which is just a tad finer than plain old 320!

Anyway, I thought I'd bring it up because I rely heavily on the grit stamped on the back of the sheet rather than feel - especially the finer grits. And in the sequence of sanding with successively finer grits, going 400, 600, to P800 would just roughen up what you did with the 600 grit - aarrgghhhhhh!!!

Regards

Quote:

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Originally Posted by boehlertaught

The big problem is my memory though. My mind is like a full computer hard drive...

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Sometimes it's as if my brain is a 3 1/2" floppy...

I read about this some time back in Fine Woodworking magazine, but that was before I started tinkerin' with 1911's. I didn't pay much attention to anything over 320 grit at the time.

Does 3M clearly mark the number with "P" on the package? It must not be too clear as others have noted. While in rougher grades, it may be noticeable, when we get to 1000+ it may be hard to tell until you open the package.

Thanks again for the info.

Quote:

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Originally Posted by FredBart

Does 3M clearly mark the number with "P" on the package?

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Yes & no!

I've seen 5 sheet 3M packages containing sheets of P400 (back of sheets marked P400) with the packages labeled 400 (in a hardware store) and P400 (in an auto parts store).

I think the secret to knowing what you're really getting is to rely on the labelling on the back of the sheets - and not the package.

Regards

All the joking aside niemi24s this could be a serious issue if we don't pay attention. Luckily we can "feel" the paper prior to using it.

After spending hours scouring the web for info, this is the best narrative I've yet found on the subject, but the little grit comparison chart is hard to see: http://www.i-car.com/html_pages/tech...2/072902.shtml

neimi, Thanks for the info. By clicking the chart you posted I was able to print it at almost page length. (easy to read). LOL

Quote:

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Originally Posted by BobbyBailey

By clicking the chart you posted I was able to print it at almost page length. (easy to read). LOL

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Thanx for the hint - takes a lot of the eyestrain out of reading it.

I posted that last link only reluctantly because it brings up the JIS grit standard. So now we have CAMI for the coarse stuff, FEPA for the fine stuff and JIS for the really fine stuff!

Maybe.

Regards