help with sandpaper

[pen-turners]

Hey all,
My dad picked up a bunch of sandpaper at a flea market and I have never seen this stuff before. They are almost clear and are 3M Imperial Microfinishing films. They have a marking of 273L 5 Mil NO5 and 60u. Does anyone know what these markings are??? I also have some that appear to be aluminum oxide and are marked 3M 273L 5 Mil TC1 and 40u. Is there somewhere to find a conversion for grits???? Let me know if you can help.

Chris

 

[Carole in VA]

Not sure about the numbers cause I am not in my shop, but the microfilm is fantastic for scary sharpening. Is it adhesive backed?

 

[btboone]

I use some of that stuff in disc form for finishing my titanium rings. The 5 mil would be how thick the stuff is .005", and the grit is the 60u 60 microinch particle size. I use that grit for rough sanding like sanding away a gold inlay after it is set in a ring and work down to 9u, which can go straight to the polishing wheel from there. If I had to guess, I'd say that the 60u is something like a 400 grit, and a 9u is something like 1000 grit.

 

[pen-turners]

I'll have to try it out and compare to my known grits. Couldn't go wrong at $.50 a roll!!!!

Chris

 

[jdavis]

Price is right. Let us know how it works for you.

 

[J. Fred Muggs]

Here's one site with a pretty good comparison chart:
http://www.homesteadfinishing.com/htdocs/Sandpaper%20equivalency%20chart.htm

Seems your 60u is about 230 grit and the 40u is about 320 grit

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