Ok One last time........Just for you.....!! How many particles are on 180 grit paper? How many particles are on 2000 grit paper. Fracture the 180 grit particles all you want there will NEVER be any more particles on that paper.
M.J. Orr
OK, join the rest. It isn't the shaggiest dog in the world.
SHEESH!
Does this mean that a closed coat paper of one grit sands finer than an open coat paper of the same grit? Does it make a difference what the abrasive material is?
-- Martin Long Island, New York
I had noticed that older worn sandpaper would give a smoother surface than the next finer grit of fresh paper would. After pondering this for a while, I figured that it was due to clogging, and you ended up burnishing instead of sanding. I think this is at least possible. robo hippy
mac davis wrote:
Probably less clogging than simple grit shedding. As mentioned many times, the stuff breaks into smaller pieces and dislodges from the adhesive. With higher smooth paper to grit ratio, you'll heat rather than cut, eventually.
I take clogging to be that fiber grab which I can remove with my file card or that crepe stick. What always happens when you try to sand a piece too wet.
Geo
I got it - too bad I have loads of the Rhino "waste-of-money" paper as well!
Ray
SNIP ......... ========================= Not necessarily true. Open coat and closed coat use the same grit size, but don't have the same number of points per given area.
Ken Moon Webberville, TX
Doesn't alter the fact that worn 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?
Well, now we've finally gotten to something I agree with.
It isn't the same, it just leaves a finish which compares with, because the maximum grit size has shrunk..
Or do you still believe the bush burns but is not consumed?
So then Ken, do you beleive that worn 180 grit open coat is the same as new
240 grit open coat OR that worn 180 grit closed coat is the same as new 240 grit closed coat???For bonus points just answer...... Yes/No
Odd... My position hasn't changed. I've been saying from the beginning that they're not the same. You agree with me now?
I dispute that. Do a scratch test on plexiglass so you can *see* the difference.
Worn 180 will *not* leave the same finish as new 240. Characterize, or cariacaturize, that statement however you wish; it's still correct.
-- 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?
As long as we are still revisiting this important issue; didja ever notice how friends, relatives and customers, as they fondle a velvety smooth bowl, feel our pain with a real concern for the agony of skipped grits and the heartbreak of recycled papers?
I tried to substitute a used 2200grit brown paper bag from A&P for a
2600grit paper bag from Kroger's, but it wasn't the same.Grits are often fractured or torn from their backing in steps of 100,
120,150,180, 240, etc. instead of 90, 140, 195 etc. Who picked these numbers ...why? How many grits are available or must we recycle worn intermediates for the inbetweens? :(Turn to Safety, Arch Fortiter
Mike, Ken was commenting on Derek's statement that finer grit paper has more cutting points per square inch. If the cutting points per square inch is an indication of fineness, does that mean an open and closed coat paper of the SAME grit will give different finishes. Just so we are on the same page, an open coat paper has less abrasive material and more open area to resist clogging.
To all, For a given grit, does the finish you get depend on the abrasive material used for the sandpaper.
Does particle size distribution have an effect on finish? Or do we believe that every particle on the paper is the same size?
-- Martin Long Island, New York
Arch,
Please stop it, you are killing me!
ROTFLMAO
We have a microscope here so the people involved could send me two or three samples and I could publish the result.
Course -- I think that spoil the fun and the debate. ;-)
I am pretty sure that garnet fractures - and that's how it stays "sharp" but for AlO (Aluminum Oxide) paper? Not sure. Suspect that it abrades and clogs - not fractures and clogs. At least that's what the standard "material engineering" texts would have you believe -- assuming I can remember where I saw it. :-)
...So maybe you split the argument up to consider the various types of sandpaper and we can all gird for battle here. :-))
George wrote:
Sorry had that backwards... :-(
There is an implication -- when something breaks in two - you now have two smaller pieces. So.... You would have to measure and see the degree of degradation of particle size...
However, since not all pieces would fracture you would probably get some scratches from the larger pieces until _all_ pieces fracture. A little tougher than it sounds I would think -- to ensure that many thousands of particles all had at least one fracture...
So I would think that measurement would show a significantly smaller number of "large" scratches as time went on - but probably at least _some_ larger scratches from the "few" remaining pieces still within the original particle size distribution.
An applied scientist would tell you that "100 Grit" meant most of the particles would be "darn close" to 100 - but there would be a distribution of particle sizes (probably fairly sharp) about the mean (average) particle size. Now if you fracture the majority of the pieces all you have to answer is "How do they break?". Do they break in two? Or... does a small piece break off a piece that stays on the paper.
Inquiring minds want to know! Or do they? :-))
They've already been published. Read the referenced "Sandpaper 101." That some will not acknowledge it in no way alters reality.
Note the crystalline structure
Thus the original post, where I remarked that this particular type of abrasive seemed to have the right stuff. It held the backing and the grit so firmly that the first did not delaminate, and the second were selectively demolished, though not released, so as to cut without heat buildup (from the slick spaces between grit) producing a finish equal to the next finer grit.
Not surprising, given that a fracture or two would reduce even the largest to the level of the largest in the next grade.
So, _I_ have done the research. I would say if you have not,you should, or not attempt puerile challenges to one who has.
"Reality" also includes the fact that "Sandpaper 101" does not in any fashion substantiate your claim that worn 180 paper is approximately equivalent to new
240 paper. [snip of analysis, assumptions, and conclusions -- but no actual research]
Uh-huh. You haven't yet done the _very_basic_ research which I challenged you to do: produce test scratch patterns on a piece of plexiglass, where they will be readily visible, from new 180, worn 180, and 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?
I was fine up to this point. What is your point?
My apologies if I have offended you.
My point was that I am in the habit of going back to basic research when a topic like this does come up. And looking for myself is not a problem. :-) -- in case you thought it wasn't.
The reference books with material similar to what you quoted are on the shelf above me.
Now I agree with you on all but one crucial point. What will be left after some use. Will _all_ the pieces have fractured? -- or just most? Unless all the pieces fracture you don't get a finer grade of sandpaper.
Only a look with a microscope would tell you the final answer. The test with plexi glass might give you the answer as well.
Enough said. I should not have responded the first time.
lighten up.
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