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Sanding/polishing porcelain beads in a tumbler

I'm looking to tumble porcelain bisque (not the final firing, still soft enough to sand off impefections), and polish the final fired porcelain beads in a tumbler. See attached photos of a final fired porcelain bead for the scale.

I'm wondering if you know what media, burnishing compound etc I should be using, and for how long.. I already have a 3lb capacity Lortone Tumbler with stainless steel shot currently for polishing metal. But I believe this tumbler also does rocks.

Picture of Sanding/polishing porcelain beads in a tumbler
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Triclaw2 years ago

so what did you do ?

Triclaw2 years ago

use grog

Triclaw Triclaw2 years ago

ok I get what you are doing now , by hand would be a ton of work . Use grog at a 50 or smaller mesh and I would not add any compounds to the tumbler it will mess with glaze if that's what your going to do with it.. I would fill the tumbler tight with the beads then add the grog stop and check half hour intervals . As for small river rock can get a pet or craft stores its the natural polished stones . Antler is harder to get but it can be cut and shaped to fine blunt point to smooth clay and burnish it

http://ceramicartsdaily.org/pottery-making-techniques/ceramic-decorating-techniques/going-low-tech-a-step-by-step-guide-to-burnishing-pottery/

Also I forgot that porcelain does not burnish well ,Sorry been a bit seen ive worked with porcelain

jarris (author)  Triclaw2 years ago

Any particular type/size? And should I add any burnishing compound?

Triclaw2 years ago

35 to 50 you will have to keep an eye on it .Why do you want to polish it as bisque you can burnish it in green state very easly and get a great polish that way with some river rock or deer antler , the tumbler is going to eat away the detail and make it round if you leave it too long I would suggest to try to burnish it as green ware leather hard either way glaze will be hard to stay put on a polished bead

jarris (author)  Triclaw2 years ago

Burnish by hand? The idea is to be able to produce these a little more easily by incorporating mechanical methods. First, I need to take a layer off as the way the beads are created are by joining two halves, sometimes the slip spills out and I have to fix the seam. In the process the marbling is sometimes covered by a layer of the joining slip, and ends up a bit muddy. By sanding at bisque I can take off a layer and reveal the marble beneath.

So before I burnish I do need to make sure that the seam is seamless and that the marble is revealed. Because this is porcelain, I find that sanding at bisque gives me a finer surface because of the 12% shrinkage compared to no sanding. And I can't imagine the objects would lose a huge amount of detail, they are fairly abstract, no surface design.

Also if I do sand at bone dry I find it quite difficult to tell what has been sanded vs what is dust settling in surface depressions. When I sand at bisque I can at least wash the bead and see what I'm dealing with.

I'm not sure what you mean by river rock or deer antler? Where do I get these in smaller scale and with a defined edge. Most of my work does have a somewhat sharp inner line that needs to be sanded/polished.

caitlinsdad2 years ago

I'm not sure but look at harborfreight for their sandblasing media which is also used for the rock polishing/tumbling thing. I would say getting some of each type to experiment wouldn't be too costly. I got a box of the 80 grit glass microbead media for one of my projects. I think they have stuff that ranges from soft walnut shells to progressively harder media which might be appropriate to tumble for polish. Good luck.