Burnishing

[Jeri]

I am very much a novice. Three years ago I returned to what I love doing so very much; pottery, after being away from the use of a pottery wheel for 35 years or so (since high school). I’ve unfortunately forgotten a great deal and have been reading as much as possible to catch back up.

 

The problem I am having I’ve been working on burnishing pots, and I’ve been having a bit of trouble. I’m using a polished stone rather than terra sig. My problem is they keep exploding in the kiln. The method I’m using is to rewet bone dry ware after I’ve sanded it smooth. Am I not allowing the burnished pot to fully dry once again, or am I doing something else wrong?

 

Everything I’ve read thus far states to burnish only the outside, is there any special reason for this? One of the items I wish to burnish is an agate stoneware bowl, as I believe it may be a better solution than clear glaze to bring out the beautiful marbling effect of the contrasting clays.

 

Jeri

 

 

[savant]

Have you tried firing a pot that you have not burnished? just to see if the problem is in the throwing. If you have done this with successful results

I would think that you maybe haven't let your burnished pots dry completely. Has for not burnishing the inside of pots, I use terra sig on the inside of

mine all the time with great results.

[faber]

try this- use a rubber kidney to smooth the pot just after throwing it, this will start the process of pushing the grog in. Then when your pot is leather hard put it back on the wheel and smooth again with the rubber kidney. Don't use water and don't push to hard.You should not have to sand your pot before the final burnish. When your pot is bone dry burnish it with your stone but instead of using water use a small amount of cooking oil burnish and oil small areas at a time. Try not to push to hard if you do the surface of your pot could crack, just use the weight of your stone. I hope this helps.

[Jeri]

Have you tried firing a pot that you have not burnished? just to see if the problem is in the throwing. If you have done this with successful results

I would think that you maybe haven't let your burnished pots dry completely. Has for not burnishing the inside of pots, I use terra sig on the inside of

mine all the time with great results.

 

 

 

Yes, I've fired the agate pots before with great success, and used a clear glossy glaze.

[Jeri]

try this- use a rubber kidney to smooth the pot just after throwing it, this will start the process of pushing the grog in. Then when your pot is leather hard put it back on the wheel and smooth again with the rubber kidney. Don't use water and don't push to hard.You should not have to sand your pot before the final burnish. When your pot is bone dry burnish it with your stone but instead of using water use a small amount of cooking oil burnish and oil small areas at a time. Try not to push to hard if you do the surface of your pot could crack, just use the weight of your stone. I hope this helps.

 

 

 

I'll give this a try, I plan on starting another set of pots today. Thanks for the tip!

[pauline]

I am very much a novice. Three years ago I returned to what I love doing so very much; pottery, after being away from the use of a pottery wheel for 35 years or so (since high school). I’ve unfortunately forgotten a great deal and have been reading as much as possible to catch back up.

 

The problem I am having I’ve been working on burnishing pots, and I’ve been having a bit of trouble. I’m using a polished stone rather than terra sig. My problem is they keep exploding in the kiln. The method I’m using is to rewet bone dry ware after I’ve sanded it smooth. Am I not allowing the burnished pot to fully dry once again, or am I doing something else wrong?

 

Everything I’ve read thus far states to burnish only the outside, is there any special reason for this? One of the items I wish to burnish is an agate stoneware bowl, as I believe it may be a better solution than clear glaze to bring out the beautiful marbling effect of the contrasting clays.

 

Jeri

 

 

 

[Lucy]

I've had good success by burnishing with a stone just prior to leather hard. You do have to handle the piece carefully, but this has worked well to get a good burnish without having to rewet the work.

 

I like the idea of testing a piece without burnishing. See if the piece is the problem or the burnishing. Be sure the work is really, really dry before firing.

[savant]

how is it going with the brunished pots?

[nelsonsa]

I use a small light bulb to burnish greenware. Lightly sand then apply baby oil to a small area of the pot then brush on water to that area and rub with the light bulb.

Some potters use just the water.

nelsonsa

[kelleyisfj]

Hi,

I like to use the techiques I learned from Mata Ortiz potters for burnishing. Although they handbuild, you can use the same principles with thrown pieces. At leatherhard, I use a fine, #32 hacksaw I've cut in half. Using the edge with the teeth, scrape over the surface in multiple directions. This will reveal the high and low sections. Don't brush off the raised bits but use them to even out the surface with the smooth edge of the hacksaw It's amazing how consistent the surface will become. I don't burnish when it is leather hard--too easy to make dents in the surface. When it is DRY take a dry clean-up sponge and begin burnishing with that. You should get a bit of sheen. Then, rub a small amount of vegetable oil on the pot and let it partially soak in until you get a white sheen on the surface. Take your polished stone and rub very gently using the weight of the stone only. Go into your meditative state and enjoy burnishing! I don't see why you couldn't burnish the inside the same way, as long as you can reach it. I just burnish the part you can see on the inside. Make sure your clay has very little grog to get a good burnish.

 

Can't imagine how you would have trouble with explosions unless you make your pieces too thick and get air bubbles. I try to keep mine no more than 3/8 inch thick.

 

Of course, to keep the burnish, you need a very low kiln. That might be a good topic of discussion--what temp do people use for burnished pieces? I've heard everything from 018 - 010.

 

Good Luck!

Kathleen

[hansen]

Jeri: Most likely the pieces are either too thick, not quite dry, or you are firing too hot too soon. Unless there is a problem with the agate clay body. Proper agate or marbled clay formulation involves using the SAME CLAY tinted in different colors. Clay incompatability could be the source of the problem. Burnished wares need only be fired just past quartz inversion, say maybe cone 022-018. In a way, your clay is best formulated specifically for the way you are going to work with it.

h a n s e n

I am very much a novice. Three years ago I returned to what I love doing so very much; pottery, after being away from the use of a pottery wheel for 35 years or so (since high school). I’ve unfortunately forgotten a great deal and have been reading as much as possible to catch back up.

 

The problem I am having I’ve been working on burnishing pots, and I’ve been having a bit of trouble. I’m using a polished stone rather than terra sig. My problem is they keep exploding in the kiln. The method I’m using is to rewet bone dry ware after I’ve sanded it smooth. Am I not allowing the burnished pot to fully dry once again, or am I doing something else wrong?

 

Everything I’ve read thus far states to burnish only the outside, is there any special reason for this? One of the items I wish to burnish is an agate stoneware bowl, as I believe it may be a better solution than clear glaze to bring out the beautiful marbling effect of the contrasting clays.

 

Jeri

 

 

 

[Jeri]

My apologies for not replying sooner, life happens and took me away for a spell. Thank you to everyone for your comments and ideas.

 

Savant and Lucy, I have in the past had several successful firings with both unbrunished pots and unburnished agate ware.

 

Faber, I gave your suggestion a try this morning, so far so good. I’m looking forward to being able to put it in the kiln within the next week or two after the pots have fully dried.

 

Nelsonsa, I like the thought of the light bulb, perhaps the end of it will be easier to hold onto than the polished stone. They keep trying to jump out of my fingers.

 

Kelleyisfj, Sounds very interesting and something I’ll have to give a try. I get excited about trying new ideas and methods, even if they seem to fail at first. It’s all part of the learning process.

 

Again, thank you everyone for your thoughts and comments. I’ll let you know how the pots I worked on today come out of the kiln.

 

Jeri

 

 

[anna]

My apologies for not replying sooner, life happens and took me away for a spell. Thank you to everyone for your comments and ideas.

 

Savant and Lucy, I have in the past had several successful firings with both unbrunished pots and unburnished agate ware.

 

Faber, I gave your suggestion a try this morning, so far so good. I’m looking forward to being able to put it in the kiln within the next week or two after the pots have fully dried.

 

Nelsonsa, I like the thought of the light bulb, perhaps the end of it will be easier to hold onto than the polished stone. They keep trying to jump out of my fingers.

 

Kelleyisfj, Sounds very interesting and something I’ll have to give a try. I get excited about trying new ideas and methods, even if they seem to fail at first. It’s all part of the learning process.

 

Again, thank you everyone for your thoughts and comments. I’ll let you know how the pots I worked on today come out of the kiln.

 

Jeri

 

 

 

[anna]

Peoples,

i do not understand the use of oil.

In the firing all the oil will burn away, so why use it?

I use very thin plastic bags to burnisch.

In each hand i hold a frotted bag, put my claypiece on the wheel and let the wheel do the turning for me, while i hold the frotted bags against the pot.

easy!

[JeanB]

Hi Jeri

It seems to me that the re-wetting of the clay is where your problem lies. Years ago I modelled a tortoise. The last work was on the shell which took time as it was to be very realistic and of course the clay was drying out. The exact area which I was re-wetting, exploded clean away from the body. The effects were gross and I still can't bring myself to throw away the head and feet which had such character! I burnish in the last stages of leather-hard, usually with the back of a spoon and sometimes with some baby oil to keep the work at that stage of leather hard until I'm finished - it seems to stop the drying process. I have never had reason to burnish inside a pot except for the neck but as burnishing aligns those tiny clay particles so tightly together, it may seal in moisture. I have never been advised not to burnish inside though and would go ahead with your bowl. My work is pitfired which is quite a harsh process where you lose a lot of work but so far I have only had some very fine small cracks on a few pieces.Burnishing is a great finish as you are not separated from the clay by the glaze - it feels warmer too.

I'd love to know how you are getting on.

Cheers

Jean

[Jeri]

Burnishing went great, love the soft tones and feel of the pots. I'd like a little bit more of a shine though. However, I'm sure that with more time and practice I'll get it mastered. I like using the rubber rib when leather hard much better than sanding, and reweting the clay as I go. Thank you all!

[faber]

Jeri, I'm so glad it all worked out. Here is an idea for more sheen it works for me. When you are finished burnishing use a round soft sponge (the kind you use for pottery they come in student kits or you can buy them seperate,most likely you have one). Wrap the dry sponge in a thin plastic grocery bag, make sure to not have any creases in the bag that is around the sponge, then lightly buff your pot with it. You will be amazed at the shine you get. I only fire to 018 when I burnish but I am pit firing and my pots are not functional. This will not work with any pot that needs to be functional. Good luck and Happy Potting.

[Jeri]

Thank you for the suggestion! I will give it a try with the next pot I work on. It's so great to have the support system like this, and I am so very greatful for everyones replys!

 

Jeri, I'm so glad it all worked out. Here is an idea for more sheen it works for me. When you are finished burnishing use a round soft sponge (the kind you use for pottery they come in student kits or you can buy them seperate,most likely you have one). Wrap the dry sponge in a thin plastic grocery bag, make sure to not have any creases in the bag that is around the sponge, then lightly buff your pot with it. You will be amazed at the shine you get. I only fire to 018 when I burnish but I am pit firing and my pots are not functional. This will not work with any pot that needs to be functional. Good luck and Happy Potting.

 

[venetiancat]

Hi Jeri,

I burnish my wares all the time, and I find that it works best using a polished stone when the pots are a "black" leather hard-that is to say, leather hard when the clay is its darkest before it begins to dry out. I use a Giffen grip to hold the pot in place, or simply stick them to the wheel head with a little water, and burnish using the wheel. I fire to cone 04, and the burnish still holds. I also burnish before applying terra sigillata (you can read about terra sigillata here on my website) and then buff the pieces with a chamois.

 

 

 

kelleyisfj Hi,

I like to use the techiques I learned from Mata Ortiz potters for burnishing. Although they handbuild, you can use the same principles with thrown pieces. At leatherhard, I use a fine, #32 hacksaw I've cut in half. Using the edge with the teeth, scrape over the surface in multiple directions. This will reveal the high and low sections. Don't brush off the raised bits but use them to even out the surface with the smooth edge of the hacksaw It's amazing how consistent the surface will become. I don't burnish when it is leather hard--too easy to make dents in the surface. When it is DRY take a dry clean-up sponge and begin burnishing with that. You should get a bit of sheen. Then, rub a small amount of vegetable oil on the pot and let it partially soak in until you get a white sheen on the surface. Take your polished stone and rub very gently using the weight of the stone only. Go into your meditative state and enjoy burnishing! I don't see why you couldn't burnish the inside the same way, as long as you can reach it. I just burnish the part you can see on the inside. Make sure your clay has very little grog to get a good burnish.

 

I'm going to try this Kathleen, I LOVE Mata Ortiz pottery, and I hope to study with them someday.