Grinding Pots to Remove Glaze or to Smooth Foot - Asked by Louis Ford

[George Lewter]

Louis Ford

• Does anyone have suggestions on what works best when grinding glaze from the bottom of pots? We have a bench grinder (with 2 discs) that grinds, but will quickly take a chunk out of the pot along with the glaze.

Richard Ruckert

• Louis - watch this video this might help https://www.youtube.com/watch?v=ldZvMvPZZuY&feature=plcp
• It's a video on how to inexpensively turn your wheel into a flat lapping machine

George Lewter

• A bench grinder can work if the wheels are perfectly round and balanced. If out of balance there is some vibration and the large mass of two wheels adds some hammering momentum to the grinding action. This is what causes the chipping of the clay.
• For grinding small amounts of material a Dremel type tool with diamond bits works great. Even if they vibrate a bit, They don't have enough mass to break off chunks of your foot. Both the tool and an assortment of diamond grinding tips are quite inexpensive at Harbor Freight. 
• You can spend more money on a Dremel brand tool and are likely to get less vibration and depending on the model, more power.

•  Even if you make the flat surfacing tool for grinding bottoms, a rotary tool with diamond bits is still handy for rounding over sharp corners and flattening glaze defects and bumpy bits of grog protruding through the glaze on the rims of pots. 

[George Lewter]

Richard, 

The video you linked to is great, and answers more than just the problem of grinding off glaze drips.  Flattening the foot to eliminate wobble is very desirable, as is having a very smooth bottom surface that will not scratch a buyer's furniture.  I've seen people like a piece, pick it up, feel the bottom, frown, and walk away.  Steven Hill always smooths the bottom of his pots, and I took that lesson away with me. There are numerous ways to smooth the bottom, but the method you found is the most elegant I have seen for getting truly flat bottoms on a whole batch of pots.  Thanks.

The video is at --- http://www.youtube.com/watch?v=ldZvMvPZZuY&feature=plcp

You can get an 8 inch diamond coated flat lapping disk at http://www.amazon.com/Grit-Diamond-Lapidary-Faceting-Flat/dp/B009TZ... (currently $24.99).

Wet grinding will eliminate dust issues and prolong the life of your disk. A small fountain pump would be in order if you want the full recirculating water system. Or you could rig a gravity feed system to supply a small amount of water that you would manually remove from your splash pan.

[George Lewter]

I found diamond grit lapping discs for Hsin-Chuen Lin's potters wheeltop technique on ebay for $18.95.  The 8" diameter in 170 grit was what I thought was the best to work quickly and still leave a smooth finish.  

[George Lewter]

An inexpensive, yet very effective way to smooth your feet of clay is to purchase a diamond sanding block. It takes a minute or so to rub out the grog and clay roughness on the bottom of a small or medium sized pot. You will be left with a very smooth bottom that people will notice when they compare to the work of others who don't bother with this finishing touch. Stadea sells these blocks in a number of grits, and you can expect to do 100 or more pots with a given block. They sell for less than $20 each plus shipping. It is worth noting that stoneware and porcelain fire very hard. Though silicone carbide grinding materials will smooth your pots, you will be replacing your grinding medium much more often than if you use diamond grit. I think the longevity outweighs the higher cost for the diamond grit.

50 Grit for fast cutting, 120 grit for smoothing, 200 grit general smoothing, Set of 4 assorted grits from China $15.79 at this posting, Set of 7 assorted grits Stadea Brand $57.99 at the time of this posting. 400 and higher grits can be used to polish glaze areas where you have ground out defects or smoothed over excessively rough crystalline surfaces.

[Patricia Bridges]

See Patricia's blog --- Unnecessary Roughness

 

[Norm Stuart]

That is clever attaching a lapidary disk to the bat. I've used the same pumps from Amazon to put into ceramic fountains, but I'd never have thought to put it all together with a potter's wheel. A very Rube Goldberg set-up.

[Ray West]

Go to www.facebook.com/sequoia.pottery for information on grinding and flattening pottery feet.

[Lawrence Weathers]

Hsinchuen's Video and technique is excellent but will cost $100 plus.   I use a not quite as good but much cheaper approach.  I just put a silicon carbide, cemented cutting disc on my wheel head. It really works pretty well for smoothing the bottom of pots it's not aggressive enough to grind off large glazes lumps running onto your shelf.