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Comparable abrasives


#1

I have a question about finishing jewelry pieces. I usually end up
using different types of abrasives for different parts of a piece.
Maybe a sanding stick for flat, open areas, abrasive sponge or maybe
bristle disc or something else for a hard to reach area, and so on.
If I could just use one abrasive method to cover the entire piece,
for example, graded sanding papers, there would be no problem. That
doesn’t always seem practical. When I switch from one method to
another, I’m never sure how they match up as far as abrasive grit.
How does a “fine” 3m sanding sponge compare to a 440 bristle disc?
How does that compare to my “medium” Moore’s disc? Did i just move
backwards from a fine to a more coarse grit? Some abrasives, like
sandpaper, usually have a grit or micron size specified, but I’m not
even sure if they are really equivalent between different brands, and
many abrasives are not specified that way (just “coarse”, “fine”,
etc.).

I don’t know if there is a solution to this, but as a scientist-type,
I wonder if there is some way to test these to at least rank them in
some way, as to equivalent abrasive level (grit?). I was wondering
about some sort of scratch test. Is there such a thing, or some other
technique to shed light on this?


#2

Hi Todd,

I have a vague memory that somebody either did a comparative abrasive
chart (on silver) some few years ago (like 5-10) but I can’t remember
who, or even if it got past the talking phase. I suspect it came up
first here on Orchid, so a search of the archives may be of some use
to you. Can’t think of any keywords beyond the obvious.

FWIW,
Brian


#3

have a vague memory that somebody either did a comparative abrasive
chart(on silver) some few years ago (like 5-10) but I can’t remember
who, or even if it got past the talking phase. I suspect it came up
first here on Orchid, so a search of the archives may be of some use
to you. Can’t think of any keywords beyond the obvious. Thanks
Brian, I did find some previous posts as you mentioned. I was
wondering if one could do their own test, something like: take a
piece of silver, abrade it in one direction withone abrasive, then
abrade with the second abrasive at right angles to the direction of
the first one. Then look to see if the first set of scratches is
visible under magnification. Not sure if this would work, as one
would have to somehow apply the two abrasives “evenly” in some way.
If sandpaper, using the same pressure and number of strokes, etc. If
the twoabrasive types are very different (bristle discs and sponge
for example) it might be challenging to make the test valid. Maybe
there is some clever approach?


#4

I’m a big “fan” of 3M abrasives for the creative arts market. If you
go to their site you can get all the info you want on their products
from Tri-m-ite wet or dry papers, radial bristle discs, cubitron
bands, Imperial films and papers and sanding bands, their diamond
bands and psa diamond products. up to their FX wheels that conform to
your work pieces. the list is exhaustive, but the grit/technical info
can be gleaned from their site. Its all there you may have to use the
sitemap. If you go to shows they usually bring copious amounts of
printed materials too - make your own comparative charts!..

another excellent reference I use is from Karl Schmid’s fine Tools
abrasives comparison chart- it’s pretty detailed and complete for
basic abrasive products. from micronised grits to say a standard 80
grit ruby paper. lots of useable info there too. The link to the
Schmid site is : http://www.ganoksin.com/gnkurl/ep807g rer


#5

hi Todd,

Errrr. no. The whole point of progressively finer abrasive is that
it cuts less, per stroke. (but leaves smaller and smaller grooves in
the surface.) So if you stroke a surface with 10 strokes of 80 grit,
and then 10 strokes of 220, of course you’ll still see the 80 grit
scratches.

My memory of the whole abrasive ‘chart’ discussion was that the end
goal was a chart of final finishes, not anything to do with 'x
amount of metal gone per stroke of Y abrasive". There are way too
many variables to make that practical outside of computerized gear.

FWIW,
Brian


#6

A few years ago, I ATTEMPTED to prepare a chart comparing the
different abrasives that I used from time to time. I’m not convinced
that it’s right, so user beware. I used the the was
provided by the manufacturers to describe their product and
intrepreted it as best as I could.

Jamie


#7
Errrr. no. The whole point of progressively finer abrasive is that
 it cuts less, per stroke. (but leaves smaller and smaller grooves
in the surface.) So if you stroke a surface with 10 strokes of 80
grit, and then 10 strokes of 220, of *course* you'll still see the
80 grit scratches. 

Yes, that assumes the second abrasive was finer than the first, and
it would tell you that such this was the case. If the second abrasive
was coarser than the first, the scratches would be removed, and it
would tell you that the second abrasive was coarser. Remember, my
point is that you might not know before hand.


#8

Thanks to all for all the Jaime, your table is very
close to what I am interested in. The only thinkg is that it is
assembled from from different manufacturers. One wonders
if they are comparable. Being the scientifical type, I was trying to
think up a method to directly compare the different abrasives. My
initial thought is that onecould take a large piece of SS and use a
coarse piece of sandpaper to score it. I would put a fixed weight on
the small bit of sandpaper and drag it across the SS sheet with a
string to create even abrasion all the way across. I would do this
with, say, 3 different successively smaller grits, making 3 lines
across the SS sheet. Then I would take each abrasive media to be
compared, and drag it across at right angles to the original lines. I
might drag them across several times at the same location to simulate
repeated rubbing with the abrasive. Then a macro lens photo or
microscope could be used to take pictures where the lines intersect.
Visually, onecould perhaps determine the RELATIVE grit (coarseness or
whatever you wantto call it) of each abrasive by observing how they
abrade each of the 3 reference lines. One tricky thing would be the
bristle discs (how fast, how much pressure).


#9
I was trying to think up a method to directly compare the
different abrasives 

Well Todd, the problem is that abrasives are much more complex than
that. You can Google abrasives and find volumes written about them,
if you are so inclined. I think the effort in question is less than
worth the effort myself, but whatever floats yer boat…

I’mnot an abrasives expert, but there are some things in play that
everyone should know anyway. First factor is “aggression” - how
sharp and how tough the abrasive is. Silicon carbide or carborundum
is maybe the most aggressive abrasive out there. Next is probably
aluminum oxide, which is emery among other things. Diamond is hard
and sharp but lessaggressive, surprisingly. Now, andybody who knows
more about abrasive than I do is welcome to correct me or embellish,
because I’m not an expert, as I said.

What that means is that you get a sheet of carborundum sandpaper and
stroke it across a sheet of metal. The grit cuts deeply and quickly
and most importantly the crystals largely stay intact. Then you
stroke it again and it’s roughly the same as the first stroke - it
cuts deeply and quickly. Do the same thing with aluminum oxide -of
the same grit - and it’s nowhere near as sharp or tough. It cuts
less on the first stroke, and many of the crystals break, leaving a
softer edge. So the second stroke is only 90% (whatever) of the cut
of thefirst stroke. As you keep sanding the sandpaper gets "softer"
and you actually almost end up with a finer grit sandpaper in the
end. Almost, not really. Diamond has it’s own properties - the
diamond crystals cleave easily, but when they do they expose fresh,
sharp edges, not soft ones. So it’s not just a matter of comparing
grit sizes, youalso need to factor in WHAT the abrasive is - it’s
not all about grit size.

Then you have the backing material and the glue used to bond the
grit to it and you get into pretty much infinite possibilities.
Andthat’s just sandpaper, it’s not even getting into wheels and
points andslurries.

Whole books have been written about this stuff, as you’d expect.