Removal of rough iron pieces on stoneware fired BRT

[Alice Bell]

Hello, just wondering if anyone has a solution to the rough bottom of fired Buff Raku Trachyte. The iron pieces are very coarse, is sanding an option? 

[Babs]

Grinding is an option.There have been a few posts about what people use.

Some crystal glazers gribd all the time.

Diamond disc attached to wheel. Carboradum bitheads or stones.

Eye protection and mask would be essential

[Hulk]

Hi Alice,

I've glued 6" diamond wheel to a bat (my least favorite bat, which can still be used for clay, flipped over...) for polishing feet - works great! I run the wheel at a moderate speed, wet. The sludge (wet dust) likely wouldn't change how my clay behaves - I'm cleaning up before and after anyway.

A courser grit would probably be better; this was so inexpensive tho'

 

[Mark C.]

Have you tried wire wheeling the bottoms-(bench grnder fited with a wire wheel.)works great on most stoneware

[1515art]

I really like the idea of grinding wet to eliminate dust issues, I’ll have to pick up a suitable diamond abrasive wheel, I’ve glued wet sanding disks to old throwing bats but their useful life is short. I did lapidary work many years ago and we used a flat lap that didn’t seem much different than a wheel head with a 1” lip to dress the backside of polished stones a much more involved version of Hulks method. 

Sometimes I’ll chuck a finished piece on my giffen grip and hang a bag of water over the wheel head to provide a steady drip of water then use a diamond burr while spinning the ceramic ware on the wheel. Not the easiest way to go about finishing the bottoms, but if I’m not in production mode I’ve saved a few glaze disasters and am able to produce very clean edges with glazes that like/need to run and have smoothed bottoms with it.

[Hulk]

"...steady drip of water then use a diamond burr while spinning the ceramic ware on the wheel." 

Good idea! 

Regarding the diamond wheel glued to an old bat, I went with 1200 grit because it was cheap and for sure would leave a polished surface. However, it is a bit slow - a 600 is probably fine enough to get a nice polish, and would be faster. Back to the other hand, 1200 is forgiving and doesn't "grab" much. 

[Magnolia Mud Research]

I have used the following techniques to make the bottoms of coarse clay body items smoother.  They all work, some better than the others.  For really coarse clay bodies, the combination of 1, 2, and 6 are what I try to remember to do. 
Random order of use:

1. burnish the contact area at the stiff leather hard stage.
2. apply terra sig to the contact area at bone dry stage and burnish.
3. smooth the bisque ware contact area using fine emery paper taped to a smooth surface, or with a medium and then fine grain sharpening brick. 
4. fine emery paper (~200+ grade) glued to a bat on the wheel. use wet.
5. polish glazed fired items with emery sharpening brick.
6. polish glazed fired items with a medium to fine flap wheel on a grinder or drill press.

Diamond wheels are OK, but are overly expensive, in my opinion, for most items unless the sales price of the final ware item covers the cost of the diamonds. 

LT

 

[liambesaw]

I got the 300ish grit and 1200 grit ones, but I use a rough stoneware. 10-15 bucks isn't expensive 

[1515art]

40 minutes ago, Hulk said:

"...steady drip of water then use a diamond burr while spinning the ceramic ware on the wheel." 

Good idea! 

Regarding the diamond wheel glued to an old bat, I went with 1200 grit because it was cheap and for sure would leave a polished surface. However, it is a bit slow - a 600 is probably fine enough to get a nice polish, and would be faster. Back to the other hand, 1200 is forgiving and doesn't "grab" much. 

Specifically, I use an old camel,back bladder it has the bag (naturally), hose,  valve, a hook to hang  and a snip of the mouthpiece with a diagonal cutter makes the nozzle. Holds plenty of water and you have great control over the drip. If you have access to medical supplies an iv drip works too.

[Hulk]

Burnishing helps loads!

[Babs]

Metal rib at trimming time using giffen grip is a quick burnishing method which might just be enough.

[Alice Bell]

7 hours ago, Magnolia Mud Research said:

I have used the following techniques to make the bottoms of coarse clay body items smoother.  They all work, some better than the others.  For really coarse clay bodies, the combination of 1, 2, and 6 are what I try to remember to do. 
Random order of use:

1. burnish the contact area at the stiff leather hard stage.
2. apply terra sig to the contact area at bone dry stage and burnish.
3. smooth the bisque ware contact area using fine emery paper taped to a smooth surface, or with a medium and then fine grain sharpening brick. 
4. fine emery paper (~200+ grade) glued to a bat on the wheel. use wet.
5. polish glazed fired items with emery sharpening brick.
6. polish glazed fired items with a medium to fine flap wheel on a grinder or drill press.

Diamond wheels are OK, but are overly expensive, in my opinion, for most items unless the sales price of the final ware item covers the cost of the diamonds. 

LT

 

Wonderful thank you!