Advice needed please

[TerraGazer]

I need help please. I initially posted this under techniques and got no reply and hope I am okay to post this here.. This is my 1st attempt to polish rocks. I am using a harbor freight vibratory tumbler, as I wanted to keep the organic shapes of my stones. Vibrating mostly very smooth banded hard (7) wonder stones that I had found in dry river wash along with a larger angular agate and a purple quartz stone. I am using resin filler (the little pyramid shapes) and the required moisture for a "slurry". So, prior to 1st grit, all the banded hard wonder stones were very smooth, already as they were river washed. I ran the first grit for about 9 hours. . And was extremely pleased with end of 1st grit outcome... I then pretty carefully cleaned the bowl of sludge and grit. I then 'thought' I had cleaned rocks pretty good too. Again, I was pretty happy at his point as I was seeing nice colors come through etc. But! After about 8 hours of 2nd grit I pulled some random stones and rinsed them, only to find some of my initially smooth stones now have tiny pock marks. Others are still very smooth and pretty much exactly where I would want them to be at prior to pre-polish.
So can someone explain what happened: Did some of the larger more angular rocks pinhole pock the small, those softer-ish ones?
Or
Did I miss cleaning out all the 1st grit ?
Or
Have I been way too impatient and let the 2nd grit do the rest of its job before getting anxious about the pinholes?
Any and all help, pointers, criticism and grumbling, etc. is welcomed and invited !

 

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[CaliRockhound]

Hi TerraGazer,
I have done some tumbling of rock. With a vibratory type tumbler the filler should be ceramic cylinders (non-abrasive). The resin is most often used with the rotary type of tumbler. One school of thought is to leave the original rough grit in for the entire grinding process, just check daily to see if the moisture is enough so that the stones slide past each other. If not, just use a spray bottle to add a little at a time until the stone slide past each other. You should get another bowl just to do your polishing, that way you avoid any chance of cross contamination and again use clean or new non-abrasive ceramic cylinders for the polishing step. After the polishing you'll probably have to burnish your stones. It is an easy step and only takes about a hour to do. All you'll need is a couple of shavings off a bar of ivory soap and a little water and you'll end up with a higher polish. You can check this out by doing a search on the internet for vibratory tumblers technics.
As far as the pits that have shown up in your stones, chances are those are areas that are just a little softer than the surrounding stone or the pits were exposed as there are often little holes called vugs that were hidden by the layer of grains above it. You can try and start with the original course grit to see if they disappear.
The agate and the purple quartz (amethyst) are all approximately a 7 in hardness and can be tumbled together.
Hope this helps

 

[JLeonhardy]

I have a dual barrel lotto that I love.

I'm assuming you mean the wonderstone that's a rhyolite, which is softer than the quartz agates and amethyst you're tumbling. In addition, it's been my experience that agate is about a half step softer than amethyst. Sometimes more if your agates are in a rind or aren't pure quartz.

First, forget about using and media until the polishing stage, unless you're using it as a filler.

When I'm using the rough grit, I'll mix the hardness of the stones (currently running fluorite and amethyst), mostly because the harder rocks will take down the shape of the softer rocks faster. It's the quartz thats pitting your wonderstone.

Also, with vibe tumblers, you usually don't need as much water as for a rotary tumbler. The lotto's I have are designed to work on a couple of tablespoons of water, and they'll take agates start to finish in about three weeks. Double check the instructions for the proper amount of water.

When you get to the polish stage, especially with soft rocks like wonderstone or fluorite, a dry polishing stage with media works really well, though I prefer soft media like crushed corn cob. For wet polishing, I prefer the plastic pyramids cause the act as a great polishing vehicle as they wear down.

Before the polishing stage, I run them in the vibe in a soap mix, then I run them through the dishwasher in a plastic bowl or container with holes punched in the side and bottom.

 

[Eu_citzen]

I'd also like to add that some rocks are made up of several minerals - sometimes of different hardness.
If one of them has Mica in them, like granite, they can turn out real bad after a few grits.