Grinding The Bottom Of Your Pots

[Rebekah Krieger]

I haven't seen much information about this, but the clay body I use tends to have a lot of grog on the bottom leaving a rough foot (and lip sometimes)  I had my husband grind a practice bowl smooth.  It worked except the grinder left the food of the bowl looking dirty. (the clay body is white)

 

What can be done to avoid this? is there another way? I read about using a sander on the bottom of porcelain but I don't know if also goes for cone 6 stoneware.

[oldlady]

try using a rubber rib on the last part of the trimming stage.  push that grog back level so it does not stick out above the surface.  do NOT use a damp sponge last.

[Mark C.]

My fellow stoneware studio production potter uses a brass wire wheel on a bench grinder-this is also what I use if I have any stoneware in a fire. This does not leave marks and smooths the bottoms -this is after the glaze fire. You can use wire wheels but they can darken the bottom some.

I rub all pot bottoms while unloading my porcelain glaze loads with a ceramic rubbing stone its about 2 to 3 inches wide and about 3/4 inch thick-they are white and can be had a ceramic tile stores (not big boxes usually)

these bars are often sold as three sections joined together and you snap them apart-they are the same material as Oldlady is speaking about in below post only larger and flatter for rubbing.

Mark

[Biglou13]

Do you have formula for self made , pottery based rubbing stone?

 

Have you tried wet sanding.

 

There is a wet diamond wheel process but wheel is pricy.

[oldlady]

pottery supply places sell a small white stone stick about 4 inches long by 1/2 inch.  about $3.50.  it is a handy size to take to any sale just in case you missed using it as you unload the kiln.  most of my work has flat bottoms and they are fired on sand so cleaning up immediately as they come out of the kiln is necessary.

[bciskepottery]

I use 3M diapads to finish the bottoms of pots . . . here is one source

http://www.toolocity.com/diamond-hand-polishing-pads.aspx (It looks like they are out of some grit blocks now) 

 

Basically, a version of "wax on, wax off".  I dip the sanding blocks in water and polish away.  I recommend 100 and 200 grit blocks for most items, although I do have a couple of 400 grit for making a surface really smooth.  I use these on Highwater's Little Loafers and Red Rock, Standard 266, 306, and 381, and Laguna Dark Brown and Soldate 60.  Those run the gamut from smooth clay to groggy clay.  Do not recommend using them for dry sanding; too much dust.  And, they clean up bisque really nice, too. 

[ayjay]

i use a diamond stone to just quickly run over the bottom and take off any sharp edges at the transition from flat bottom to sides - I don't find it ever needs much it's pretty much done with the trimming and sometimes a touch up with a bit of scratch (Aluminium Oxide paper) after the bisqued stage.

 

I've also recently started, since seeing the idea on here, putting terra sig on the bottom of my pots (none of those are fired yet).

[Rebekah Krieger]

Thank you for all the responses!!! My husband has a grinder, and a sander at work.  I will look into these things! I think my problem is I have been smoothing the lip of my pieces with a damp sponge or damp leather. depending on what is nearby.   But as far as the foot goes, I haven't done anything other than regular trimming.  OH The things I learn from you! You are all so amazing for all your constant help!! 

[Nancy S.]

I had the same problem!! So now I burnish the bottom of my pots when they're leatherhard, using the back of an old spoon. Pushes the grog in and makes it nice and smooth.

 

FWIW, if your old spoon is tarnished, using it to burnish will rub the tarnish off and the impurities that end up on the clay will fire out in the bisque.

[Guest JBaymore]

As a woodfirer I live by the grinder.

 

I use a slow speed wet grinder for finish of most work (Hig speed wheels create heat and vibration.... bad for ceramics work).  HAcve both silicaon carbide and alumina media.  Some stuff I use a diamond blade on a 4" angle grinder for rough first work.  Also sometimes use a wet daimond blade on a Dremel.

 

best,

 

.................john

[Pres]

I use a wooden bat with a sanding pad(S/C P120 paper made in Canada) put the bat on the wheel with pins, use a medium to fast speed to smooth the bottom. This leaves very little in the way of a mark. I do compress the bottom of the pots also with a rib unless I use a wiggle wire to cut off.

[yedrow]

I'm a firm believer in dealing with the problem as early as possible when it comes to clay. Like 'oldlady' said, use a rubber rib to burnish the bottom. After that, there is a green wheel for the Dremel that works quite well on small imperfections.

Joel.

[docweathers]

To grind the bottom of pots smooth, I got a 14 inch silicon carbide cement cutting disc and center it on a 14 inch plastic bat by fastening a 1 inch OD washer into the center of the bat. You can then just lay the grinding disc on the bat so that hold the center hole slips over the washer. it works well for smoothing bottoms of pots but it is not aggressive enough to grind big lumps of glaze off. A bench grinder still works best for that.

[Mark C.]

I need to do lots of pots and taking them to a potters wheel is just not fast enough. The only time they see a wheel is when they are born then trimmed-they its trial by fire and maybe a grinder next to kiln before price stickers and boxing into van or on to galleries-taking them say 300 at a time back into my studio would kill me not to mention how slow this would be.

My porcelain only needs to be hand rubbed with a rubbing stone-The bench grinder with a green stone found here(these are cool running crystolon bench grinding stones)

http://www.amazon.com/Norton-Pedestal-Abrasive-Straight-Thickness/dp/B007MRXHAE/ref=sr_1_1?ie=UTF8&qid=1380086264&sr=8-1&keywords=norton+green+grinding+wheels

I have an 8 inch doulbe wheel grinder but 6 inch is more common.I use the 60 and 80 grits-you can find them cheaper but norton is the brand and  cystolon is the specific wheel

Also a bench grinder with a brass wire wheel for stoneware and other uses.

I keep a 120 fine wheel for steel sharpening and smoother work.

The courser stone is for glaze drips

I also keep to dremels at the ready one with a green carbide wheel the other with a fine point diamond bit.

With these tools I can process whatever comes out of the kiln every week or two.All these tools are within 3 feet of car on car kiln.

Mark

[neilestrick]

220 grit wet sandpaper- the black stuff.

[Chris Throws Pots]

Hey rebbylicious and All,

 

Here are two resources for pottery pedicures which I've found particularly interesting. I still haven't started messing with the process - I finish the trimming of every pot by burnishing the foot with a green Sherrill Mud Tools rib and/or a polished stone - but some day...

 

1: Hsin Chuen Lin's extra fancy, arguably over-complicated, but ultimately super cool method that turns your wheel into a wet grinder. It requires a bunch of equipment, including an extra splash pan, but it's pretty slick.

 

2. Jeff Campana's writing "Foot Fetish" about his trial and error process of grinding feet for a glass-like finish. http://jeffcampana.com/blog/

 

Enjoy

 

Chris

[Biglou13]

I use 3M diapads to finish the bottoms of pots . . . here is one sourcehttp://www.toolocity.com/diamond-hand-polishing-pads.aspx (It looks like they are out of some grit blocks now) 

 

Basically, a version of "wax on, wax off".  I dip the sanding blocks in water and polish away.  I recommend 100 and 200 grit blocks for most items, although I do have a couple of 400 grit for making a surface really smooth.  I use these on Highwater's Little Loafers and Red Rock, Standard 266, 306, and 381, and Laguna Dark Brown and Soldate 60.  Those run the gamut from smooth clay to groggy clay.  Do not recommend using them for dry sanding; too much dust.  And, they clean up bisque really nice, too.

 

Ty for the link super fast shipping

They work amazingly well, much better than any of the sandpaper/pads I've tried.

Lowest I got was 100, wish I would have gotten one more coarse

Pads are much stiffer than I expected.

I've only had them for a day, are you getting good life span on yours? Have you had issue with them getting clogged?

the bottoms get super smooth, so no scratching the good furniture

They work so well that they create somewhat of a knife edge with the newly smoothed bottom, but easily remedied with same pad.

[jrgpots]

I keep reading this thread because it makes me chuckle. My Moma told me never to grind my bottom no matter how rough it was. She said someone would love it just as is it was without having to advertise it. I wonder what my mother would say about all of these potters gringing their bottoms and then talking and posting about it.....lol

 

Jed

[Babs]

Carboradum  stones, and carboradum bits that fit onto drills are good, the latter come in round heads, different sizes. that get into corners. I use them hand held, small and easy to take with you.

Compression after turning feet does press the coarse bits back into foot , but some do tend to exude after glaze firing so the above combination does work.

Jed, I guess your Mom didn't have to deal with, "Will this scratch my dining room table??"

[jrgpots]

She placed doileys under everything. But you have a good point. You need to grind you bottom before you put it on the table.....right?

 

In all honesty, I use a freedom 1/4 hp wood carving/jeweler's tool with the green grinding stone.

 

Jed

[bciskepottery]

 

I use 3M diapads to finish the bottoms of pots . . . here is one sourcehttp://www.toolocity.com/diamond-hand-polishing-pads.aspx (It looks like they are out of some grit blocks now) 

 

Basically, a version of "wax on, wax off".  I dip the sanding blocks in water and polish away.  I recommend 100 and 200 grit blocks for most items, although I do have a couple of 400 grit for making a surface really smooth.  I use these on Highwater's Little Loafers and Red Rock, Standard 266, 306, and 381, and Laguna Dark Brown and Soldate 60.  Those run the gamut from smooth clay to groggy clay.  Do not recommend using them for dry sanding; too much dust.  And, they clean up bisque really nice, too.

Ty for the link super fast shipping

They work amazingly well, much better than any of the sandpaper/pads I've tried.

Lowest I got was 100, wish I would have gotten one more coarse

Pads are much stiffer than I expected.

I've only had them for a day, are you getting good life span on yours? Have you had issue with them getting clogged?

the bottoms get super smooth, so no scratching the good furniture

They work so well that they create somewhat of a knife edge with the newly smoothed bottom, but easily remedied with same pad.

 

 

I have a 50 grit I use for really rough stuff . . . but I also try to minimize the amount of post-firing clean-up by making clean, compressed bottoms.  Mostly I use the pads to remove any kiln wash that sticks to bottoms and feet, and to smooth a rough surface where -- even after ribbing the bottom when done -- some grit comes to the surface after glaze firing.  Yes, the blocks are stiff . . . I use them whole (as is) and I also cut them into quarters -- the edges seem to wear out faster than the middles on my work.  They can get clogged . . . when that happens I usually wash them out in water. 

 

As far as life-span, that depends on how much clean up is needed.  I've used some for a months, others wear quicker if the surfaces are rougher.  I usually buy a half-dozen or so at a time, so a fresh one is always handy. 

 

For glaze drips, I use my dremel with a grinding bit.  The diamond pad can, however, be used to polish up the surface after the dremel does its thing. 

[docweathers]

I didn't realize how great my own $20 el cheapo bottom grinder ( described above) was until I looked at the horizontal jewelers grinders at $2-$3000.

[Guest JBaymore]

Norm,

 

I've had my eyes on a lap wheel for a long while.  Just haven't been able to pull the trigger on the price yet.

 

I do have a slow speed wet bath grinder ...... but the lap wheel is the perfect tool.  Sigh...........

 

best,

 

........................john

[Min]

Diamond flat lap on wheel head with a clay pancake works. Some of the flat laps are very thin peel and stick type, the one I have has an aluminum backplate, about 1/4" thick, 120 grit, need to keep it wet while using. 

 

http://www.ebay.com/sch/Rocks-Fossils-Minerals-/3213/i.html?_from=R40&_nkw=diamond+flat+lap&rt=nc&LH_PrefLoc=1

[jrgpots]

Diamond flat lap on wheel head with a clay pancake works. Some of the flat laps are very thin peel and stick type, the one I have has an aluminum backplate, about 1/4" thick, 120 grit, need to keep it wet while using. 

 

http://www.ebay.com/sch/Rocks-Fossils-Minerals-/3213/i.html?_from=R40&_nkw=diamond+flat+lap&rt=nc&LH_PrefLoc=1

Great idea