|Tumbling - first stage - 90 grit.
Here's what I am currently tumbling in my Lortone Qt-12 Rotary Tumbler:
Pietersite, Ametrine, Golden Rutilated quartz, fossilized red horn coral, Dinosaur bone, chrysoprase and a
few other random things. I normally tumble the more expensive materials so that I will have something nice
for my efforts!
Click to enlarge any photo - some expand 2X - huge full screen photos!
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|Another view of the batch of gemstones that have completed the rough 90 grit stage and are ready to advance to the next step in the process.
The next step is the medium 220 grit grind. Since I use valuable premium material, and since each batch is worth about $400 to $800, I want
to insure that only well shaped stones with no pits or deep cracks are advanced to the next stage.
Keep in mind that only the first coarse stage affects the shape! Whatever shape you have that you put in the subsequent stages will not
change at all. The medium and fine grits don't remove much material and do not change the shape - only a very thin layer of rock and
scratches are removed.
|Since I removed rocks that weren't ready to advance to the next stage, this meant that I had to add material to the barrel to keep it filled to
the ideal capacity. There's several things that you can do but it's important to only add material that's at the same stage. I usually have a
container of rocks that have already been thru the rough stage but just wasn't nice looking. I kept them to add when needed to bring my
barrel level up to optimum levels. In this particular case, I had some small chips of ametrine that I added. I forgot to take pictures at the
time though. Since these are small they not only bring the barrel level up, they also act as grit carriers!
It's best to have a mix of sizes so that the stones are polished quickly and evenly. If you only have large size rocks they don't grind or
polish nearly as quickly as they do when you have small sizes as well. I also add ceramic shapes to buffer the stones and to act as grit
and polishing media carriers. As the next page will show - I didn't add enough of these and the quartz variety stones such as rutliated
quartz and especially the ametrine had bruising on the edges!
|I started the first grind stage on Feb. 26 & made this page March
16, 2018. This batch of stones finished up about 6 weeks from the
start date! To check out how the stones turned out (Hint: they're
great!) then check out my
TUMBLING RECIPE RESULTS PAGE
|Step 1 : Coarse stage. coarse 90 grit - 1 pound. I TableSpoon Borax, ivory soap flakes. Run one
week. 12 Pounds of rock. Water to just under last top layer of rocks. 5/8 full.
Step 2: Coarse stage continued. Empty out and rinse and add same ingredients as above. Add new
rocks as needed to bring barrel to 5/8 full. Run one week.
Step 3. Medium Grind stage. Medium 220 grit - 1 pound. Borax and ivory soap flakes. add rocks or
ceramic shapes to bring barrel to 5/8 full. Run one week.
Step 4. Fine grind stage. Fine 600 grit - 1 pound. Borax and ivory soap flakes. add ceramic shapes or
smooth rocks to bring barrel level to 5/8 full. Run 1 week.
In this instance, I ran for almost 2 weeks because I didn't have time to advance to the next step. This may
have contributed to some of the quartz bruising.
Step 5. Polishing stage. Tin oxide 1 1/2 cups. It is very expensive but worth it. 1 TBLSPN Borax and
ivory soap flakes. Run one week. I have a separate clean barrel just for polishing so as to be sure that it
is not contaminated with grit stuck in the rubber walls of barrell.
Step 6. Burnishing stage. Thoroughly clean rocks and add water to TOP of tumbler. Add dawn dish
detergent and Tide Free laundry detergent. Run for 30 minutes and not longer. You can tell by how
dirty the water is that this really makes a difference!
I've read to only use ivory soap for burnishing as it will damage the rubber barrels. I've not noticed any
problems using dawn and Tide Free but it may be because I only burnish for 30 minutes or so. I
definitely wouldn't try using anything other than those two and not for longer than 30 minutes either.
The rubber barrels are expensive (the QT-12 is $85 not counting shipping) so you don't want to risk
ruining a barrel!
|LORTONE QT-12 ROTARY TUMBLER
|Shown above is the ceramic cylinders that are used to cushion the stones and to act as grit carriers and polish media carriers. These cylinders
make sure all surfaces of the stone are exposed to the grinding or polishing media. These act to buffer and cushion the stone and really help
with quartz to avoid having bruised edges. These are somewhat expensive but last a good while. I get them, and all of my tumbling supplies from
Kingsley North as they have the very best prices on pretty much anything in the lapidary or mineral collecting hobby when it comes to supplies
Shown below is a bag of them that I've saved for polishing. I use the ones in the bag just for polishing to insure that there isn't any grit
contamination. These rinse off pretty clean but there is no sense taking any chances and it's just faster to have dedicated ceramic shapes set
aside just for polishing. Also shown is a bag of plastic pellets which are also used for the same thing, with a couple of special cautions: you
can only use the pellets in one type/size of grit or polish. This is because grit can become embedded in the pellets and cause scratches when
you change to the next lower grit size. Personally, I just use them in the polish stage, and not often at that! The plastic pellets can ONLY be
used in a rotary tumbler and NOT in a vibratory tumbler. You'll note that in the bag of pellets that there are some small pieces of tumbled stones
that I haven't bothered to pick out. Once, I found some pretty valuable brandberg amethyst slices that I had left in this bag!
The ceramic shapes last pretty much forever when just used for polishing as they don't wear down. I don't use them in the coarse grind because
they would disappear in a rapid and expensive way. I mainly use them in the medium and fine grinds and they do get smaller and smaller. The
ones I changed over to "polish only" show how they've decreased from their original size and shape!