Official Luthiers Forum!

A great finisher shared this link a while back as something everyone needs to hang on their finish room wall. I agree.
http://www.fingerlakeswoodturners.com/downloads/Sand%20Paper%20Grit%20Comparison.pdf

Following this has helped my recent finishes a bunch because.... not everyone minds their P's

I have found that 3M and others do not differentiate. They put 600 grit on the outside label for paper that is marked P-600 on the paper.
I just ordered a bunch of paper from Fastenal and found the same thing. They were good about getting me the right stuff, but still... it was sold as 800 grit, but arrived as P-800. Using the chart above, you can see that the abrasive on P-800 is 28.9 microns or about the same as 400 grit!

Discovering that Micro Mesh uses it's own grading system was a little disheartening.
Because of what I had on hand, I was using P-600, 1000 (cami), and then 1500 micromesh.
That means I went from 25.75 microns, to 9.5 microns and back to 30 microns.
No wonder my finish ALWAYS left something to be desired.

So, if you are getting ready to sand out a finish, print out the page in the link above.
It will be so worth it.

My current builds are testament. I finally have a bridge between P-600 and 1000 grit, which is P-800, P-1000, P-1200 and P-1500. My finish has never looked so good.
Will post pics when done.

dl

Thanks !
Interesting stuff,
enough to drive one crazy,
if one didn't know all the differences!

To add to the confusion Cami and P grades have a range of particle sizes on the paper, Micron papers are more uniformly graded and Trizact sheets use a different method of polishing. Scrapers and sharkskin anyone?

I noticed in the home store that the 3M sandpapers at 800 and below indicated P-grade, but 1000 and 1500 had no indication of P-grade on the back of the paper. I called 3M to inquire if the 1000 and 1500 were P-grade or not. After waiting (a long time) for the tech support person to ask someone else. I was told that the 1000 and 1500 papers were NOT P-grade. Its interesting that in the same line of papers they would change grades...

_________________
Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

I will have to run out and rummage through my sandpaper. Thanks for posting.

I too brought it up with 3M and they were not real receptive to the suggestion that they label things correctly.

My speculation is that sandpaper at those grits is such a specialty item that the big box stores, and auto parts stores do not have a high enough demand for the product that we need.
There must be a supplier for automotive abrasives, but I have not found them yet, I am guessing because the equipment they use is so far removed from what and how they do what they do.

If anyone knows an auto body finisher, ask them where they think we should be able to get sandpaper in the grits that we need.

dl