Which abrasive grading standard?
John K Jordan
>Recent discussions of finishing and grits confuse me since I found out that 600 paper is not necessarily 600 paper.
A recent article in FWW#176 (Apr'05, "Finish line, True grit", pg 117) describes the difference between the CAMI (US ANSI standard) and FEPA (European, P) grading. For example, 600 CAMI is equivilent to P800. 800 CAMI~=P1500. Micromesh states in their literature that their 1500 paper is slightly courser than common 600 grit sandpaper, whatever that means. I have 0000 steel wool from the hardware store that feels far coarser than the good stuff (Liberon)
Learning about the differing standards was a big relief in a way since I was sure some of my 400 paper was much finer than other and I didn't know enough to understand why. But it was also the source of a new anxiety. Now I look for the P in the grading number but evidently thats not enough.
According to the article, the notation is not always consistent. Sometimes the P is not on the paper but on the packing. Sometime the P is missing entirely. The article gives some examples: 3M uses the P consistently for FEPA papers. Norton uses FEPA for most paper but does not use the P at all, but their silicon-carbide wet-or-dry paper is CAMI. Yikes. Klingspor uses FEPA and marks with a P except some of their garnet and al-oxide paper is FEPA but not marked. Mirka uses FEPA and labels it all with P. The author warned that it was beyond the scope of that article to do a review on every type or brand of sandpaper.
How's a turner to stay sane?!! Is all of this second nature to everyone but me? I just sand until the marks are gone, but grabbing a piece of sandpaper paper could be a wasted step backwards.
It seems to me that discussons and comparisons that mention grit sizes are meaninless without paying careful attention to and reporting the grading standard.
JKJ in East TN
