Green Sandpaper Revisited

Wrong. Worn 180 paper is simply that: worn 180 paper. It may remove wood at approximately the same rate as new 240 paper, but it is *not* equivalent to the finer grade. The abrasive particles are still the same (180) size, they're just dull, and the scratch pattern reflects that.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

Yeah, right.

Talk to the Tormekers about what happens when you break the corners on the grains.

Or the users of garnet paper....

You're talking to a Tormeker now, George. I've had one for three years. Since you're apparently unfamiliar with the way it works, know that it uses a stone that's *harder* than the grains to break them into finer grains. It's not the same process as wearing the grains down through use.

Likewise not the same as wearing the abrasive particles down.

Believe what you want. It doesn't change the facts: used 180 is not the same as new 240.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

Breakage of the sharp edges is what it does, same as sanding wood. AlOx does _not_ wear down in contact with wood. Defies physics.

The smaller sharp points from brittle fractures are effectively finer. When you re-dress your Tormek, you break away the fractured grains, exposing fresh gross points.

Gee I don't know about this Doug. George may be on to something. I will do a test......I will just use 180 grit until it cuts like 240 and then like

320 and then like 400 and then like 600......and on and on....well you get the idea........... Think about it Doug, we only have to buy one piece of sandpaper from now on......................YMMV...........

Cute.

Now let's have a quick reality check about sandpaper. The grit is determined by screen sizes. For our example, let's say that the screen which traps the 150 grit is above, ours is going to be labeled 180, and what passes us to the screen below, 240. We begin with a range of sizes, and adhere them to a backing. The process vibrates them a bit to distribute, so you've got a bit of the gold-panning effect, where the bigger roll upward.

Now the larger of those particles, because they are larger, extend farther from the adhesive or back. They are brittle, and so fracture, producing _smaller_ grains with tighter abrasive points. They are also more vulnerable, due to friction, to that phenomenon we all love, breaking free of the adhesive so as to leave ugly marks as they are chewed through our smoother surface. As both effects favor the ones who stick their necks out, worn sandpaper approaches the grade of the lower mesh size as it is used.

With this green stuff, the adhesive appears to be very good, holding grit far beyond any I've used, including some red resin-on-resin (look at sanding belts) types. This means I've still got grit making sanding dust beyond the time the paper-backed 180 has shed virtually everything and is burnishing the surface like the Kraft paper it is.

I wouldn't mind seeing some substantiation of this claim that the abrasive particles *fracture* (as opposed to wear).

Think that if you want. Me, I always figured there was a reason that sandpaper was made in different grits, some coarse, some fine.

No doubt you do. Trouble is, it's dull 180-grit particles. And those are *not* the same as sharp 240-grit particles.

Do a test: using fresh 180, well-worn 180, and fresh 240, sand up some areas on a piece of plexiglas where you can see the scratch pattern easily.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

I tried it.. damn paper backing wore out after only 100 uses... cheap disposable crap!

mac

Please remove splinters before emailing

Look it up. You'll learn more if you have to put the effort into it. You refuse gratis information.

While you're at it, give some thought to how they came up with that Mohs thingie of what scratches (wears) what. If wood "wears" AlOx - which it does by breaking the sharp edges - not rounding them, why doesn't it just blunt your gouge, which is cut by AlOx?

So then I do just need to use one piece of 280 grit on a project and keep sanding with it until it "fractures" all the way to 2000 grit and the piece is completed?

It's like being in the classroom again. Surrounded by those who know nothing, but keep spouting off.

For you, and the others who haven't the sense to shut up or the ability to look up

In other words, that's just your opinion, which you are unable to substantiate.

Hello.... it *does* blunt the gouge. That's why I have to resharpen it from time to time.

Try the test I proposed, putting scratch patterns on plexiglass, and post your results. A photo in alt.binaries.pictures.woodworking would be interesting.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

So... put up, or shut up.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

Point out to me where in that article that they claim that "fragmented" sandpaper cuts like the next finer grit....... If you can't then might I suggest you head back to that classroom.........By the way......watch much O'Reilly Factor?????

M.J. Orr

~

As I said, floppy as overdone mafalda, but holding on tightly each time it's reattached.

The second point mentioned - the adhesive holds tightly to the grit, even on the edges, where you'd expect a bit of peelback or breakdown.

The shelve life

That remains undetermined. The stuff I got is fresh - to me. Unfortunately that's about all we can say about any paper we get. Unlike the higher-carb beer they don't give us a "born on" date.

Then there is the way it's used. I am a low-heat sander, so I don't have a lot of problem with velcro melt, or with cloth separation, where they seem to use some pretty crummy glue. One variety of paper which I'm _not_ buying again is extremely prone to paper/cloth detachment, and smells like hide glue, which seems utterly inappropriate for the purpose.

Ok, one last time to learn to think. If the finer papers are made with smaller pieces, and the bigger pieces break up into smaller ....

Unfortunately

higher-carb

*You* learn to think. Smaller pieces does not necessarily mean a finer cutting edge. What do you get if you break a square in half?

One last time: learn to back up your claims. Where can you substantiate your claim that worn sandpaper of one grit is equivalent to paper of a finer grit? You do that, and I'll admit you're right. You can't do that, and I'll continue to say you don't know what you're tallking about.

Just because worn 180 paper removes stock at about the same rate as new 240 paper does *not* mean, as you appear to think it does, that it's doing the same job. Try the test I suggested on plexiglass, and look at your scratch patterns.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?