donsimpson
starting to spend too much on rocks
Duncan and Mari's Dad
Member since September 2006
Posts: 176
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Post by donsimpson on Feb 22, 2007 14:05:38 GMT -5
Discount Agate House in Tucson sells all kinds of lapidary supplies, including 8,000 silicon carbide grit. Does anyone know what you would use this for? The owner's cryptic response was "for anything that's hard to polish."
Thanx, D
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stefan
Cave Dweller
Member since January 2005
Posts: 14,095
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Post by stefan on Feb 22, 2007 14:14:31 GMT -5
It is like a SUPER SUPER prepolish- It would work well for most softer stuff (sodalite, maybe softer wonderstones, feldspars, calcites) Not really required for the likes of Jaspers and agates
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RockyBlue
fully equipped rock polisher
Go U.K.
Member since June 2006
Posts: 1,719
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Post by RockyBlue on Feb 22, 2007 14:40:02 GMT -5
Hey D! I buy my sc sandpaper from Supergrit for my belt and disc sander to use on my knife handles,i can go up to 8000 grit that will fit my disc,and i can go up to 600 grit on my belts,i go that route because i can`t tumble them because i have to keep the bottom edges flat and sharp.....Rocky
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snowdog
fully equipped rock polisher
RIP David Fildes, aka: snowdog
Member since January 2005
Posts: 1,527
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Post by snowdog on Feb 22, 2007 15:50:02 GMT -5
bet it is cheaper than the 8000 diamond paste maybe ? -- would prob be good to use on opals too --- some jades like to go way up on the grits before they "shine" too --- the diamond paste go on up to 100,000 or so , so this is pretty big compared to those ;D
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donsimpson
starting to spend too much on rocks
Duncan and Mari's Dad
Member since September 2006
Posts: 176
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Post by donsimpson on Feb 22, 2007 16:27:55 GMT -5
So what is the screen value for polish?
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rallyrocks
fully equipped rock polisher
Member since November 2005
Posts: 1,507
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Post by rallyrocks on Feb 22, 2007 16:44:14 GMT -5
So what is the screen value for polish? It varies depending both on the abrasive/polish composition as well as the subject "to be polished" material. 8,000 is knocking on the margin of polish for some materials, but I think most of the oxide based ones we use should screen out at 10,000 or higher. As mentioned diamond pastes go to 100,000 and beyond, but in my experience a majority of stones will take a glass-like polish at 14,000 or 50,000, some even as low as 8,000, while a few won't even take a proper shine using 100,000.
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Post by deb193 on Feb 22, 2007 17:25:05 GMT -5
I think things like tripoly is as course as 1000g. good AO should approach 50,000g. I also read that typical Cerium Oxide particle sizes are about 3 microns (8000g, but I think it is smaller than that). This is from CoolWrite web site ( www.cabbingmachines.com/polishes.shtml) There are two types of Aluminum Oxide: "A" and "B". Because the brand name "Linde" used to be almost synonymous with high quality Aluminum Oxide, many people still use "Linde A" and "Linde B" to describe the two types. Our Aluminum Oxide is the highest quality (99.9% pure) and equivalent in quality to Linde.
Aluminum Oxide "A" is used for polishing tourmaline, beryl, garnet, topaz, peridot, danburite, etc. Sometimes topaz, peridot and danburite don't polish well with Aluminum Oxide and polishing with diamond is required.
Aluminum oxides labeled as "A" are not all equal in quality or performance. Check the size of the grit. In order to be of top "Linde" quality, Aluminum Oxide "A" should be .3 micron in size, and Aluminum "B" should have an extremely small micron size of .05. To put this into perspective, 50,000 grit is .5 micron and 100,000 grit is .25 micron.
They offer these grit-micron conversions: www.facetingmachines.com/grit-mesh-micron.shtmlMoma's minerals sells 0.5micron AO, and gives a useful list of suggested polishes for different materials here. They mention a 0.3micron AO sold as Sapphire powder. I think I asked Shawn at the rockshed once what the microns of his AO was and if I recall he said 1/2, which is about 50,000 - but don't hold me to that. Memory is fuzzy. The polish achieved also depends onthe shapes tht the grit particles break down into. AO for example tends to break into more rounded bits that some others. While we are onthe topic, one interesting article I read was on the theory of polishing. It is not clear that it is done by scratching/abraiding. www.lapidaryjournal.com/feature/nov05.cfmA lot of this is theoretical knowledge from reading, because all I have ever used in my tumblers is RockShed AO. Anyway, don't assume everything by the same name is the same size. If it seems cheap, likely is is larger or more poorly graded micron sizes.
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Post by puppie96 on Feb 23, 2007 3:37:48 GMT -5
I tried diamond on my rubies/sapphires for like 3 months and it did not work.
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Post by deb193 on Feb 23, 2007 7:31:42 GMT -5
A lot of the stuff written about polishes is actually for damp polishing on a wheel or polish disc. It does not always translate into the tumbler. You have to be careful if you want tumbling-only discussion. FOr example, I have never heard of using diamond abrasives in a tumbler.
Once I asked about polishing slightly softer stones, such as Rosetta SZtone, some jades, petrosky stones, some starburst jaspers ... etc. I got lots of responses about how great Zam was for petrosky stone or Rapid Polish 61 was for jade, or great results with TXP, M5 ... etc.
The short of the story is that after about $30 worth of polish purchases later, when I was getting ready to see which one worked best in the Lot-O, I realized that the folks who had replied to me were all cabbers, or were speaking about results they got on a wheel, buffing plate, or flat lap. Silly me, I had assumed that on a tumbling board, I would get replies about polishing in a tumbler. Puppie, I don't think diamond works in tumblers. I wish I understood exactly why.
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stefan
Cave Dweller
Member since January 2005
Posts: 14,095
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Post by stefan on Feb 23, 2007 10:46:50 GMT -5
I think one of the reasons Diamond craps out in the tumbler is the lack of Heat and Friction- Puppie I remember the thoughts on Tumbling with diamond- I seems to think I was convinced that it WOULD work (sorry if I miss guided you) For diamond to work it need a bit of heat (opens the stones pores a bit) and friction (abrades away the scratches) As for an 8000 SiC grit- It is gonna be harsher than an AlO- The silicon breaks down into smaller sharp grains- AlO tends to round off (that is why we don't have a Silicon Polish) Daniel- That is too funny (ok not really) but for the softer stuff in the tumbler I like the Tin Oxide- it won't polish Jade (I think Cromium Oxide is the only Tumbler polish that will do the jade) but should be good on everything else
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donsimpson
starting to spend too much on rocks
Duncan and Mari's Dad
Member since September 2006
Posts: 176
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Post by donsimpson on Feb 23, 2007 11:06:47 GMT -5
Nobody said there was going to be any math!
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