US vs EU sandpaper grits

[alexreinhold]

As if the metric system wasn't enough already...  :-\

When you refer to sandpaper grits, are you referring to US (CAMI) or EU (FEPA) numbers? (see below)

 

[ValeBliz]

As if the metric system wasn't enough already...  :-\

It's the other way around man. Anyway always fepa, P grades.

 

[stratamania]

I always refer to EU P grades.

 

[BroccoliRob]

dude i don't even know how to read this chart. Is it saying cami 60 is equal to fepa P60? and cami 800 is equal to fepa P1500?

but 180 and P180 are like, a li'l diff?

Or is these 2 lists being parallel to each other just for the sake of coincidence and convenience ("convencidence"). Maybe it's just me

i always tell my nephew to study so he doesn't end up as dumb as me.

i says to him, i says "if u dont study, in 20 years when your kid doesn't come him til 2am on a school night and you try to lecture them, they'll be like 'hey old man, whats 7+8?' and you'll take one second too long to answer and bam, they'll hit you with 'yeah that's right, good night idiot' and leave you in your dirty woodpaneled living room with your warm can of PBR and empty cheeto bags feeling soooo small". He's a good kid, tho, so he'll probably be fine

 

[DuckBaloo]

dude i don't even know how to read this chart. Is it saying cami 60 is equal to fepa P60? and cami 800 is equal to fepa P1500?

but 180 and P180 are like, a li'l diff?

Correct. The columns are ranked to demonstrate the equivalent grit between the two systems.

For the OP, since pre-finish and filling is in the 220-400 range, there isn't enough difference to matter (my local woodworking store mostly sells P, so that is mostly what I buy). I don't use anything finer than 400 until I wet sand, and that's all 3M wet/dry (cami).

 

[dratini357]

I don't use anything finer than 400 until I wet sand, and that's all 3M wet/dry (cami).

Now I'm confused.

This is a 3M 800 grit that I bought in California a few weeks ago, and it says P800 on the back.
Does this mean this about 600 Cami?

 

[DuckBaloo]

I don't use anything finer than 400 until I wet sand, and that's all 3M wet/dry (cami).

Now I'm confused.

This is a 3M 800 grit that I bought in California a few weeks ago, and it says P800 on the back.
Does this mean this about 600 Cami?

Well, I may have made an incorrect assumption. I don't actually have any 3M wet and dry on hand to check. I usually have a couple variety packs.

But P800 = ~700 cami

 

[Rick]

I wonder what the grit size is based on.  I used to think it was grains per square inch.

 

[stratamania]

I don't use anything finer than 400 until I wet sand, and that's all 3M wet/dry (cami).

Now I'm confused.

This is a 3M 800 grit that I bought in California a few weeks ago, and it says P800 on the back.
Does this mean this about 600 Cami?

It does not mean much in all practicality. It would be closer to 400 CAMI. 600 CAMI is somewhere in between P1000 or P1200.

The American grading system CAMI is not used widely and given that you have 3M Paper purchased in California is testament to that.

FEPA (Federation of European Producers of Abrasives) which includes probably most if not all the leading manufacturers have pushed standards in terms of ISO and EU for many years. The chart posted is a useful chart for those transitioning from one to the other.

Here is another slightly more accurate chart. Which also shows what the grit sizes mean in terms of Average particle size in inches/microns.

http://www.autobodystore.com/paper_grading.htm