Charlest, thanks for catching the part about the p-metric abrasive grading on the Abralon pads.  I completely missed seeing the p-metric note on there.  Don't you just hate it when all of the abrasive manufacturers can't seem to standardize on a given abrasive scale???....it makes buying abrasives that much more confusing to the consumer, as if it wasn't confusing enough already.  And 3M is just as bad about switching between grading scales, where they use standard grit numbers for ScotchBrite (if you can ever figure out exactly which ScotchBrite pad you have in your hand), and they use the micron rating for their Trizact.

I guess that using different grading systems is a way to sell more abrasive products, since most consumers don't know where to find the comparison charts.

Here I come to add to the confusion.  The last time the topic of abrasive scale conversions came up, a few other sites were listed.  Here's one:
http://www.facetingmachines.com/grit-mesh-micron.shtml

     You'll notice that the scale there does not match up with the scales in the links provided so far in this thread.  I believe that the one in the link above is correct as far as it goes.  It does not include "p-metric".  I don't believe that "mesh" is the same as "grit".  I don't know what "US CAMI" from the Mirka chart means.  Is it the same as grit?  At the same time that the discussion was going on before that provided me with the link above, there was another link to somewhere on the 3M site (I no longer have that link) that gave the following:  3 micron=1500 grit, 12 micron=750 grit, 26 micron=380 grit.  Elsewhere on the 3M site, the following was given: 9 micron=1200 grit, 15 micron=600 grit, 20 micron=500 grit, 30 micron=400 grit, and 40 micron=320 grit.  You'll notice that the two scales from 3M don't even make sense compared to each other.  I wish I still had the 3M links, but I just wrote the info down when I looked at them, and I don't have the links anymore.

     I don't have any idea what to believe.  I have seen in several places in Ebonite literature that 15 micron=1200 grit, and I've been going by that, but that could easily be incorrect.  This mess is unbelievable.  I would really like to hear from somebody in the abrasives business who would be willing to give a complete and highly detailed explanation and comparison between all these scales, with the explanation including why all these discrepancies seem to exist between different companies' versions of these scales.  I'd be willing to pay for this person's time.

Shiv
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Listening to the monotonous staccato of rain on my desk top

Edited on 7/5/2003 5:31 PM

MI_2_AZ--
     No, what I saw before was not that detailed.  It included only the numbers that I quoted.  I notice that the chart in the link you just gave even included a disclaimer at the top.

     In reading this thread over more carefully since I first posted, I noticed that in this link:

http://www.buffpolishgrind.com/techinfo/gritcomps.htm

posted by DanS, that the 3M Scotchbrite colors don't match up with the grit levels that have come to be generally accepted in this forum.  

     This is really frustrating.  It seems to me that the conversion between all of these scales ought to be as straight forward as the conversion between metric and SAE measurements, or Celsius to Fahrenheit.  You don't see differences of opinion on those conversions.

Shiv
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Listening to the monotonous staccato of rain on my desk top

It readily appears that the more information we get about the grit grading, the more confusing the whole mess is getting.  Surely SOMEONE out there in industry has the RIGHT information all in one spot!!!  From what I'm seeing from clicking on the different links, not all of the grit data jives from one source to the next.   Since 3M is so involved in abrasives of different types, you'd think that maybe they have the straight scoop, but I haven't been able to locate their comparison info as of yet.  Of course, I have to admit that I haven't searched that hard yet though.

ttt for the da Shiv.

Edited on 12/5/2003 11:51 AM