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Topic Review (Newest First)
04-05-2006 03:49 PM
Richard Reed
Grit Sizes

For anyone looking for more info on "P" grit sizes, go to:

They also sell 3M grits down to 2500 in several forms and they have a 4000 grit by Minka (or maybe Mirka - can't read my own writing.)

Mosh Reed
01-27-2006 05:34 PM

01-27-2006 05:18 PM
Richard Reed
Request for Abrasives Chart

Someone sent me a request for the chart using the message center of Would you please send me a regular e-mail. For some reason, everytime I try to send it through Hotrodders, I get an error message saying the file is too large. I tried to send it to "adambond" via regular e-mail and received a reply that the adressee was not recognized. If you send me a regular e-mail, I send you a reply which is the chart and all is O.K. I have sent it to at least a half-a-dozen people so far with no problems.

Sorry for the delay

Dick Reed
01-23-2006 02:02 PM
Richard Reed

For everyone who asked me to send them the chart that I have showing the various "grits", etc., please send me your e-mail address because these thread replies say that the file is to big. My address is - just send me a blank e-mail if you have nothing to say, just make sure that someplace it says "Abrasives." I will then reply with the chart.

Dick Reed
01-22-2006 04:47 PM
327amc heres another chart. ya Reed, go ahead and send me your chart if you get the time.
01-22-2006 04:44 PM
Richard Reed I'm sorry, but I couldn't read your chart from the thumbnail sketch, it was too small. If anyone wants the chart I used, just leave a message on the thread and I will e-mail you a copy if I can get my scanner to work like it should.

ALL American Abrasive Manufacturers use the same standard. This is the way almost all U.S. manufacturers work no matter what their product is. (For example - tires) They must have standards so that if I order an apple I don't get an orange. It also insures that I get an apple of the correct size and color, etc. You don't want to buy 1200 grit paper with 240 grit bits running around in it at random. The govt. has to use such standards now or they end up with $2000 3/8 in. ratchets, etc.

Along the same vein, if you are a woodworker you are probably familiar with grit specs such as 10/0 or 1/2, etc. these are also standards and describe both the backing and the size of the granules. There is also a standard for emery paper and a different one for emery cloth. For example:

.0092 In=23.6 microns=CAMI 400 "grit"=FEPA 750=10/0 grit=emery paper 0=emery cloth ultra-ultra fine.

Dick Reed
01-22-2006 04:14 PM
327amc welcome richard reed,
thanks for the very valuable info. given you background, im sure you will have lots to contribute down the road.
att. is a chart i got from another post.

my question is, what standard grade type does 3M go by. thats all that concerns me. it wouldnt suprise me, one day in the future we will all have up on the wall of our shops, an abrasives grading chart because its getting so freakin crazy.
01-22-2006 04:01 PM
gtcway I've never ordered from this place but they have what you're looking for.
01-22-2006 03:13 PM
Richard Reed
Abrasive Materials, Grit vs. Micron

I'm a newbie to this forum and have been reviewing some of the older threads. I don't know if anyone is still following this particular thread, but I am going to throw in my two cents worth anyway. My old specialty used to be Metrology, the science of weights and measures (not Meteorology - weather.)

1 micron = 1 millionth of a meter = .0000394 inches.

"Grit" as we use it when speaking of the type of abrasives to which we are accustomed are grades of abrasive as described by the "Coated Abrasive Manufacturers Institute" or CAMI. Some equivalents are as follows:

400 Grit = .00092 In. = 23.6 microns
600 Grit = .00062 In. = 16.0 microns
800 Grit = .00048 In. = 12.2 microns
1000 Grit = .00036 In. = 9.2 microns
1200 Grit = .00026 In. = 6.5 microns

You can fill in the rest by interpolation. Interestingly enough, once you get past 240 "grit" the materials with which you are sanding are called "flours" by the manufacurers.

The "P" grades that you sometimes see are based on the grading techniques used by the "Federation of European Producers of Abrasives." Some examples of "P" grades you might run into are:

P1200 = 15.3 microns = .00060 In.
P1000 = 18.3 microns = .00071 In.
P800 = 21.8 microns = .00085 In. etc., etc., etc.

And just to throw some horse puckey in the game, you may also now see "Japanese Industrial Standard" grades such as:

J.I.S. 1500 = 10.0 microns
J.I.S. 1200 = 13.0 microns

The above is from having too much spare time to waste and just enough knowledge to be dangerous.

Dick Reed
01-17-2006 05:57 PM
327amc i love the 9 micron stuff. you might want to try sanding with 75/25 water/isoprophyl. thats what i use. it is great.
i just put a 9micron disc and a 2500 grit disc under the scope and yup, the 9 micron appears to have larger particles on it than the 2500.
01-17-2006 03:35 PM
327amc speaking in terms of micron grade,
so then the higher the # the coarser the grade????
100 micron would be........
01-17-2006 01:05 PM
mrcleanr6 9 micron is equivelant to 2000 grit and 7 is 2500 so thats not very fine, atleast not what you were talking about. i have about 500 hookit 9 mic discs sitting here i never use because they really su(k to wetsand with. the 3m dry paper is much better. on an orbital the micro paper pigtails the surface so easily its almost unusable where the dry stuff doesn't. i have seen micro paper down to .5 microns before but its not in the automotive industry. was used for splicing fiber optic cable. thats probably around the 15000 grit you were talking about. the actual difference between p graded and micro graded is in the particles. p graded paper has somewhat of a random grit size from particle to particle where as micro paper particles have gone through a filtering system and every particle is of the same exact size. i am talking about if you looked at it under a micorscope.
01-17-2006 12:06 PM
3M microfinishing paper is the place to buy the microfinishing paper. We use the 1 3/8" 9micron discs for nibbing. But this guy sells all different sizes. And there doesnt look like a minimum.
The only thing i dont know is exactly what the micron grading means. They use microns to grade the microfinishing paper, but i have no idea what it equivilates to. There is anywhere from 7 micron to 180 micron. And you can get a roll of 500 5" discs of lets say, 100micron sticky back, for about $60. thats not to bad.
If anyone can explain the micron grading scale, give me a holler.
heres a pic of some micron info also.
01-16-2006 05:58 PM
3m micro fine sand paper

Ok, i found the stuff we use. Part #'s and all. I will post the details when i get home. And its not near as expensive as i was told. (guess the company was just coverin thier ***)
01-16-2006 12:30 AM
Originally Posted by MARTINSR
Barry, the last lacquer job I did the guy at the paint store dug into this private stash and handed me a couple of sheets of 3M 15,000 grit. I was told it was used in the air craft industry to repair plastic windows. This was about 10 years ago so all we had was 2000 in the auto industry. Anyway, I painted this 31 Model A (it was only a repair involving a few panels on a car I had painted about 15 years previous) and cut it with 1000, 1200, 1500, 2000 and then this 15,000. HOLY SCHMOLY GUACAMOLE! First of all it hardly needed to be polished after the 15,000. But when it was polished it shined like a mirror RIGHT NOW.

I looked into getting some but kept on coming up with dead ends. I finally just gave up. Do you have any buddies in the aircraft industry?

YES SIR, it makes a huge difference!!!!! At my day job i have used what we call 3m microfine paper. All oem auto paint plants use it. But typically in small 1.5inch discs. We use it after 2000 grit, and always wet. and man alive!! the shine is sick
And since i paint as a hobby, i wanted some of this stuff for my own. but the folks at the local BS supply looked at me like i was an idiot.
shortly after,, i got distracted, and have since forgoten all about it until now.
i will get with our purshasing lady who deals with 3m and get some part#'s for some 5" and 6" discs and post them. the one thing i do know is, once you see the price, you will say, "Per disc?!!"

the stuff is so smooth, its almost stupid. but when you stick it on a da with a squirt of water, it actually cuts. you can see the white paste start to build up.
when i was a newbie i actually picked up an old disc and couldnt figure out which side was the sanding side. the only way i figure it out was the writing. (you can see the writing through both sides of the paper.)
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