akroes
off to a rocking start
Member since October 2014
Posts: 11
|
Post by akroes on Oct 7, 2014 13:24:21 GMT -5
After reading through a number of threads and hundreds of posts here, I am still puzzled by the use of the terms 'grit' and 'polish'. I fully understand that we start with a coarse abrasive and work through multiple levels of less and less abrasive media to get the results we want. Each step removes the scratches of the previous step (and some of the surface of the rock) but leaves some of its own scratches. Repreat with finer media until they are so small (the scratches, not the rocks!) that they are essentially invisible to the eye and we have a smooth glossy look. But at what point does a 'grit' size become small enough that we call it 'polish'? Or maybe there is actually a difference in how they work, so they are not finer and coarser levels of the same thing? I see that I can get AO 1000 grit, or just AO - is there a difference? What is the corresponding 'grit' number (if that is the right question) for Tripoli, Rouge, AO, TD, TO, etc? Do any of these interact with the rock on a chemical level as opposed to just being abrasive?
Tony
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Oct 7, 2014 17:18:53 GMT -5
Greetings [akroes] Tony if i were to give you a number it would be 17,500 grit, every thing below that number is just a pre-polish, i know of just three substences that are not polishes even if they come in 17,500 grit or beyond. 1: Silicon carbide is an abrasive and not an Oxide. 2: Boron Nitrate is an abrasive and not an Oxide. 3: Diamond is an abrasive and not an Oxide even at 100,000 grit, if you ever look at a faceted stone done by diamond you will notice that the faceted stone is not polished, but just ground clean. Please check out my Sticky's below. -- Please click images to open larger images in a new Tab, same with everything that is Underlined! I currently have a 3lb Beach (UK), Lortone QT 12/66 (USA) rotaries & 2x Viking Vibrasonic (Diamond Pacific) (USA) virbrating tumblers, with Silicon Carbide grit F80, F220, F600, F1200, with Tin Oxide (1.0 micron) & Aluminum Oxide (1.0 micron & 0.3 micron) polishes. I hail from (The Barony of Seabegs) Bonnybridge, Stirlingshire, U.K, where aliens (15mb) sometimes come for a visit & about 4 miles west from that monstrosity & 7 miles west of this new monstrosity! Sticky's: their contents are resource information 1#: Vendors worldwide (2mb), 2#: How to use the forum, 3#: How to identify rocks & minerals, 4#: Save money on expensive grits & polishes, 5#: Aussie Lapidary Forum: Rock Tumbling Guide!
|
|
|
Post by Pat on Oct 7, 2014 22:08:58 GMT -5
akroes. Good question I'll be reading all the responses.
|
|
akroes
off to a rocking start
Member since October 2014
Posts: 11
|
Post by akroes on Oct 8, 2014 13:37:07 GMT -5
Not sure I follow you, Andrew. So what is the difference (in action or process) between a grit and an oxide? I understand your comment about the diamond - that's the way I see all things - the finer they are the cleaner they 'grind' the surface. But you seem to be making a distinction that an oxide is different somehow. Do oxides interact with the rock differently (some other method than grinding them down)? If so, how?
Thanks!
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Oct 8, 2014 16:32:57 GMT -5
Greetings [akroes] Tony the best way I could describe the process is compare it to the sensitive toothpaste adverts on tv, where they show an enlarged tooth with micro-holes and their toothpaste fills the micro-holes on a tempory basis. Think of the rocks being the same as that enlarged tooth with micro-holes, what an Oxide does is first fill-in those micro-holes, then eventually covering all the rocks in a film of Oxide polish, (that film is only the thickness of the polish you are curently using,) at the same time all the rocks in barrel or hopper are abraiding with each other which eventualy causes the rocks to develop a glaze (as if they were being varnished), normally after 5 days in a rotary or 48 hours in a vibe the rocks are polished enough to fool the naked eye, however with time the polish can get better with a month in a rotary or a week in a vibe. An Oxide is another name for metal ore! The Oxide polish needs a rough surface on the rocks to adhere to in the first place, freshly broken rocks and rocks that had broken in the polish cycle will not have a polish and those rocks can ruin the entire polish batch. For noobs nine times out of ten, the rocks that are ready to go in the polish cycle, need to spend extra time in F80 (60/90) grit. But the polish you use is dependant on the rocks, Chalcedony, Glass and Quartz groups virtually polish with any Oxide. Please check out my Sticky's below. -- Please click images to open larger images in a new Tab, same with everything that is Underlined! I currently have a 3lb Beach (UK), Lortone QT 12/66 (USA) rotaries & 2x Viking Vibrasonic (Diamond Pacific) (USA) virbrating tumblers, with Silicon Carbide grit F80, F220, F600, F1200, with Tin Oxide (1.0 micron) & Aluminum Oxide (1.0 micron & 0.3 micron) polishes. I hail from (The Barony of Seabegs) Bonnybridge, Stirlingshire, U.K, where aliens (15mb) sometimes come for a visit & about 4 miles west from that monstrosity & 7 miles west of this new monstrosity! Sticky's: their contents are resource information 1#: Vendors worldwide (2mb), 2#: How to use the forum, 3#: How to identify rocks & minerals, 4#: Save money on expensive grits & polishes, 5#: Aussie Lapidary Forum: Rock Tumbling Guide!
|
|
akroes
off to a rocking start
Member since October 2014
Posts: 11
|
Post by akroes on Oct 8, 2014 18:28:52 GMT -5
Ahhh! The light bulb goes on!! Now I see what you mean. That is definitely a vastly different process - and it makes your example of the 'grinding only' diamond process clearer as well. Thanks for the info!
Now I go back to reading about this 'burnishing' everyone is talking about on the 'vibe instructions' thread
|
|
meviva
Cave Dweller
Member since July 2013
Posts: 1,474
|
Post by meviva on Oct 8, 2014 20:27:28 GMT -5
So polish is a coating on the rock not the actual surface of the rock shining? I've always wondered about that.
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Oct 8, 2014 21:16:22 GMT -5
With all respect due Andrew;
In my learning, grit is silicon carbide (rarely aluminum oxide, & in lapidary almost never zirconium oxide) and is largely used for "rough"and "pre-polish". These steps, with ever decreasing particle size, change the surface in ever decreasing ways. Grit removes small amounts of material. Once the material is completely covered in scratches of the size made by the current size grit; it is time to move on. Or, that is to say, once the scratches from the previous material are erased, it is time to move on.
Polishes (mostly metal oxides, not the sausages) are very tiny miniscule grit particles that are almost, but not quite has hard as Silicon Carbide grit, but still much harder than the item being polished. Polish, usually Cerium, Chrome, Tin or Aluminum Oxides**, (but sometimes diamond as well), change the surface of the material being polished in the very same ways as "grit" just on a much much smaller scale.
The scale of scratches made by polish is so small, that the surface begins to fail to interfere with the reflection of light, making the surface seem to our eyes like "glass". Some materials may not take a "glass" or "wet" polish and they will exhibit less sheen depending on the makeup of the stone.
For instance, agates can usually be polished to a very glassy finish. But sandstone such as indian paint stone do not have the structure necessary to accept a glassy sheen. Of course there are infinite steps in between based on the makeup of the subject.
Even if not exactly scientifically correct, I used this language to teach a 9 year old young lady (and her mom) to polish agates. They went home with two quite beautiful cabochons that night at class.
I hope it works for you too.
**Sapphire!!
|
|
|
Post by captbob on Oct 8, 2014 21:25:11 GMT -5
Turn away chilluns, here comes the "the Easter Bunny is not real" truth next.
*sob*
but, but... it sounded SO good!
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Oct 9, 2014 10:51:02 GMT -5
So polish is a coating on the rock not the actual surface of the rock shining? I've always wondered about that. We did discuss this in another thread, but I cannot find it. My info came from an old school lapidary guy and a new school industrial polishing house I spoke to recently. captain, I have no clue what to make of your post.
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
|
Post by jamesp on Oct 9, 2014 10:57:29 GMT -5
Polish is fine abrasive. Here is a size chart:
|
|
|
Post by captbob on Oct 9, 2014 11:04:01 GMT -5
captain, I have no clue what to make of your post. While Andrew's post with the toothpaste analogy sounded good, it was rather like the Easter Bunny - sounded good, but wellllll..... I was agreeing with your - removing the previous scratches until the scratches are moot - explanation.
|
|
|
Post by captbob on Oct 9, 2014 11:08:35 GMT -5
AND JamesP...I'd like to see a better, more comprehensive chart with more emphasis on grit/polish sizes that we actually use (rather than a sand paper chart) so that I may copy it for future reference. And, I would like that by noon tomorrow. Thank You Very Much
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
|
Post by jamesp on Oct 9, 2014 11:20:50 GMT -5
AND JamesP...I'd like to see a better, more comprehensive chart with more emphasis on grit/polish sizes that we actually use (rather than a sand paper chart) so that I may copy it for future reference. And, I would like that by noon tomorrow. Thank You Very Much Here is one in every language for captbob. You did not specify size....
|
|
|
Post by captbob on Oct 9, 2014 11:41:50 GMT -5
|
|
akroes
off to a rocking start
Member since October 2014
Posts: 11
|
Post by akroes on Oct 9, 2014 11:48:16 GMT -5
....Even if not exactly scientifically correct, I used this language to teach a 9 year old young lady (and her mom) to polish agates. They went home with two quite beautiful cabochons that night at class. I hope it works for you too..... Yes - perfectly - and it matches with how I thought things worked to begin with. Apparently I have the mind of a 9-year old girl! (I keep it in a jar on my desk!) Thanks, PS: my UV-10 and grit (and polish as well {Grin}) arrive tomorrow just in time for me to be gone on a weekend camping trip . Oh well, maybe I can look for rocks while I am in the woods..... Tony
|
|
|
Post by rockpickerforever on Oct 9, 2014 11:58:27 GMT -5
Do you take it out and play with it occasionally? It is good to keep your mind active and well exercised.
Where are you going camping? Are there rocks there to collect? Jean
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
|
Post by jamesp on Oct 9, 2014 12:35:03 GMT -5
What I think of your chart Was that gun mounted on your PT boat ? Must chill captbob.... Holy cow, it only has grit sizes and no polish sizes !! What next, torpedoes.
|
|
|
Post by deb193redux on Oct 9, 2014 13:14:35 GMT -5
With all respect due Andrew; In my learning, grit is silicon carbide (rarely aluminum oxide, & in lapidary almost never zirconium oxide) and is largely used for "rough"and "pre-polish". These steps, with ever decreasing particle size, change the surface in ever decreasing ways. Grit removes small amounts of material. Once the material is completely covered in scratches of the size made by the current size grit; it is time to move on. Or, that is to say, once the scratches from the previous material are erased, it is time to move on. Polishes (mostly metal oxides, not the sausages) are very tiny miniscule grit particles that are almost, but not quite has hard as Silicon Carbide grit, but still much harder than the item being polished. Polish, usually Cerium, Chrome, Tin or Aluminum Oxides**, (but sometimes diamond as well), change the surface of the material being polished in the very same ways as "grit" just on a much much smaller scale. The scale of scratches made by polish is so small, that the surface begins to fail to interfere with the reflection of light, making the surface seem to our eyes like "glass". Some materials may not take a "glass" or "wet" polish and they will exhibit less sheen depending on the makeup of the stone. For instance, agates can usually be polished to a very glassy finish. But sandstone such as indian paint stone do not have the structure necessary to accept a glassy sheen. Of course there are infinite steps in between based on the makeup of the subject. Even if not exactly scientifically correct, I used this language to teach a 9 year old young lady (and her mom) to polish agates. They went home with two quite beautiful cabochons that night at class. I hope it works for you too. **Sapphire!! ^^ Shotgunner has closest to my understanding from various readings. While there is some discussion of polishing action that might not be 100% abrasive, it is mostly just the abrasive account, aka finer scratch theory - especially when tumbling. This link outlines Finer scratch theory, Flow theory, and Chemical polish theory. ( www.attawaygems.com/NMFG/mystery_of_polish.pdfOxides are used as pre-polish (1000g) and polish (50K grit) because they are readily available in small sizes and can be manufactured or sorted into homogeneous sizes. With the advent of cheap indistrial diamonds, oxides had competition. Some polishes outside of tumbler, and more damp than wet, may have paraffin fillers or some such to coat surfaces. SOem lapidary shops used to mix AO and other ingredients to make super polishes. - but these were for buffs - not for tumblers. Or, were even more specialized for faceting lap plates. Unless you are a materials scientist, you can do fine in tumbling and polishing on buffs using the "Finer Scratch Theory" - it may not be 100% accurate, but you will almost never notice. I like this conversion chart: www.gessweincanada.com/category-s/11328.htmFinally, the effectiveness of a grit/polish is not just its size, but whether it tends to have hard edges or rounded, and whether it tends to break into a few pieces almost as large as original, or quickly breaks into many many tiny pieces. (i.e., wears out too fast). Some
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
|
Post by jamesp on Oct 9, 2014 14:06:41 GMT -5
Whats wrong with abrasive ? I must have a simple mind. No matter how you cut it abrasion is occurring. A list of how it does it could be a mile long.
here is a definition for what it is worth:
: a substance (as emery or pumice) used for abrading, smoothing, or polishing
Edit:
But, it could be a coating. Or by heat. Glass artists create a polish by heating their glass work with a torch and melting the surface scratches away. Not so simple.
|
|