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Making clay 101


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#41 Biglou13

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Posted 26 July 2013 - 06:04 PM

ok round 2

i used soup from round 1 as liquid and made more clay

i started with all dry material in bucket approx 20# dry material added about a gallon of the soup...to thich.....added approx 2 more quarts mixing with drill mounted paint stirrer. got a point of loose mud but had cottage cheese size lumps, added alittle more soup and continued to mix until there were barely any lumps left. poured mix into 2 pillow cases which are inside 2 rootmaker flower pots, drying

much better attempt than 1st try!!!!!

ill post images when dry enough to wedge.

old lady can you pm me or repost order of mixing........
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#42 oldlady

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Posted 26 July 2013 - 07:12 PM

sorry, i just found this and did not know you were asking for something from me.

 

there really is no order for mixing ingredients, just be sure that you mix some of the  dry ingredients in a dry container and add the dry bentonite and stir it in well before adding any water.  bentonite turns into a gel when it gets wet.  make sure you mix it well into other things so it does not sit in a clump. wear a respirator so you do not breathe anything in that mix. 

 

when i make glazes, i put the things into order by amount of ingredient from small to large.  this is because i have an old Ohaus scale with weights that hang on the end of the bar once you measure more than what the slides will handle.  i have 500 and 1000 gram weights.  more than once, before i realized what i was doing, i would weigh something like 800 grams of an ingredient and mark that finished.  then i would forget that the 500 gram weight was still on the scale and try to weigh 350 grams and actually wind up with 850 of that second ingredient. that is ok if you eventually notice what happened before finishing the recipe.(and if you can do the math to alter the amount of everything else to fit the error!)

 

if you are buying equipment these days, i understand that digital scales are reasonably inexpensive and accurate so you do not have to alter the order of the ingredients by amount. 

 

hope this answers your question.  sometimes your very spare way of asking things confuses this old head.


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#43 Biglou13

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Posted 13 August 2013 - 06:18 PM

I'm a little confused about silica(quartz,flint). I've read where some use it as grit, other times its the"glass" in a mix be it clay or glaze.

I understand there needs to be a flux present to melt it.
when is silica grit/grog? when is it a "glass" maker and melts?
Is this a situation where size does matter?

I have a silica sand . the screen size is 140. Sure prolly to big for glaze,
but is it to big to be used a silica component when making clay?

I got some large by product from sand mining, quartz "pebbles" Much as large. As 1/4 inch. I'm told its mostly quartz, ocassional clay pebble, tiny sharks teeth, and even fools gold (iron pyrite). How would this holdup as inclusions in clay?? currently firing to cone 6 ox, but will eventually be used in wood fired also. (Yes of course I'm testing soon)
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#44 Biglou13

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Posted 14 August 2013 - 08:14 PM

Good question big.....

Here is some insight.

"The term 'silica' can be misleading. It is important to understand the difference between 'silica mineral', 'silicates', and 'silica glass'."
......... http://digitalfire.c...ilica_1245.html

Quartz also Sio2

"Unlike silica glass, the quartz phase of silica is subject to inversion and accompanying volume and form change when fired through 573C. Room temperature quartz is called alpha quartz, beta quartz exists only above 573C.

Quartz sand is often used in bodies as grog for texture and to increase thermal expansion. Powdered quartz is used in glazes and bodies also. Quartz of very fine particle size (-400 mesh) will typically enter the feldspathic melt or convert to cristobalite during firing if fluxes are lacking, coarse powdered grades help to 'squeeze' glazes into fit. Intermediate sizes (200-300 mesh) seem to be best however, since their greater surface area exerts more compressive squeeze per unit.".....
- http://digitalfire.c...uartz_1171.html

Flint yet another. SIO2. Silica...
"A metamorphic rock high-silica content stone sometimes referred to as pottery quartz or potter's sand. Once calcined to 600C flint-stone can be easily crushed to powdered crystals. As with cristobalite, substituting quartz with flint can avoid the quartz-splitting syndrome.

Flint is usually contaminated with limestone (thus the CaO content and the LOI). There will also be trace amounts of iron and MgO. European glaze recipes often call for flint. It is typical to simply substitute quartz."

http://digitalfire.c.../flint_316.html


Ps. The clay I made in earlier post was just wedged, It was still a little moist. But it's clay nonetheless!!!! Can't wait to thow and build. With it.
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#45 Biglou13

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Posted 14 September 2013 - 09:26 PM

When making a clay body, will using 120 screen silica vs 200 make a difference?

How about 300 screen silica?
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#46 JBaymore

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Posted 14 September 2013 - 09:32 PM

The larger the particles of material, the slower they become involved in any melting.  So the answer also ties into firing cycles and the objectives of the material.  Are you using this to get glassy phase developed in the body?  If so, the larger particles will delay their involvement in a melt with the active fluxes present.

 

best,

 

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


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#47 Biglou13

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Posted 16 September 2013 - 07:47 PM

The latest recipe is a slightly modified slightly modified lehman 12-d body. See above post.. I changed red art for lizella, and used percentage of 140 and 325 silica. And decreased bentonite. (Drying slurry)

This first test 2 small yunomi just got finished In a 3 day wood firing. (Original recipe) I need to go pick them up.
Is a three day firing long enough if its held at the higher temps for a period of time. To,get the flux (nepsy)to glassify the silica? Along with ash deposits.

Also digital fire alluded to the point that smaller particle used less flux. Will the inverse apply more flux will balance the larger silica particle?

I really need to get a ceramics chemistry text book at this point any suggestions?

Sensei john and others , Again thanks for the help.
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#48 JBaymore

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Posted 16 September 2013 - 08:05 PM

I really need to get a ceramics chemistry text book at this point any suggestions?

 

"The Magic of Fire" book that comes with the Level II version of Insight glaze calc software.  Plus the online tutorials that teach you how to use Insight.  Plus having Insight (free time limited download) and learing what iot does and how to use it.  And a copy of the latest (last) version of Daniel Rhodes "Clay and Galzes for the Potter" updated by Robin Hopper (which is out of print and now expensive... but a GREAT intro book).

 

best,

 

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


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#49 Biglou13

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Posted 17 September 2013 - 08:16 PM

Rhodes book ordered.

Other when get off I pad.
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#50 Biglou13

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Posted 21 September 2013 - 06:35 PM

ok i have a new clay drying technique....

i use the slurry method..... then dry the clay in pillow cases in  rootmaker flower pots.

 

i took one pillow case full and put it on top of grate of air conditioning condenser, 

 

i got a few  weeks of drying in a day.


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#51 Biglou13

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Posted 01 October 2013 - 07:50 PM

latest batch made and wedged in about a week,   drill mixer pillow case technique  ala marcia s.

my 50 pounds dry yielded 81 pounds wedged. prolly lost a few pounds to buckets and pillow cases.

ps.  maybe im a glutton for punishment  but i wedged 81 pounds of clay by hand,  cut and slam and traditional sprial ish wedging?

 

first mix got wodfired will try and pick up on friday. will post pics asap.

 

second batch i tweaked recipe.  ill post pics to compare when wood fired.


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#52 Biglou13

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Posted 01 October 2013 - 08:59 PM

Saw a great clay body, Flashed red in wood fire, (frutani red ish)

Pried out recipe out of him.. 75 % cedar arts 50 mesh bonding. 25% gold art. After a little research I found out they are the same clay, only size is different!!! I can can see mr axe. Rolling his eyes.... And when Jedi' s roll their eyes padwan learner spat attention.
Ok the clay performed spectacularly in wood fire. Also was told it performs well at cone 6 ox electric and loved almost all glazes. It's cheap, performs well across broad spectrum of temps and glazes.....easy recipe, cheap, Yohen!, there is data along with test tile on digital fire.

Ok sounds to good to be true......so I'm suspect, No disrespect to teacher who passed it on.

Any one with any experience with this?
Comments?

( thinking out loud thinking of adding small ish percentage epk/and or helmer along with appropriate amount of nepsy, Custer, But will test as is )
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#53 JBaymore

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Posted 01 October 2013 - 10:33 PM

If that is the WHOLE recipe above... it will tend to develop cristoolite in extended wood firings..... not enough glassy phase to tie up the inherent free silica and the silica ejection from the clay crystals when chemical water is driven off.  Don;t doubt the color rendition though.

 

Remember my comments (elsewhere) about some of the best LOOKING bodies being "bad" clay bodies.

 

best,

 

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


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#54 Biglou13

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Posted 02 October 2013 - 10:29 PM

If that is the WHOLE recipe above... it will tend to develop cristoolite in extended wood firings..... not enough glassy phase to tie up the inherent free silica and the silica ejection from the clay crystals when chemical water is driven off.  Don;t doubt the color rendition though.
 
Remember my comments (elsewhere) about some of the best LOOKING bodies being "bad" clay bodies.
 
best,
 
......................john


Sensei (yoda)...... I forget nothing you say. Hopefully I won't have to pour boiling water on this body. Often beauty comes from radical thought, walking on the edge and pushing the envelope, safe is often just that, I like the idea that this body is somewhat outside of the box..... The bizen (silty) body will have to wait. ( although it has similar red flashy hi iro). My next tests will be with gold art, cedar art
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#55 Biglou13

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Posted 03 October 2013 - 10:37 PM

Made clay today very small batch under 5 # dry mix.
$6 drill from pawn shop
$7 mixing tool
$12 scale
$0 5qt bucket I had
$0 Old pillow case part 1of 2 hight tech clay drying system
$1. High tech root maker pot aka clay drying system
$0. Rain water collected

Making your own clay......... Priceless

The mix in picture will hopefully be a very flashy in woodfire.

I use three 5 gal buckets for 50# batch.

Attached Files


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#56 Biglou13

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Posted 04 October 2013 - 07:05 AM

If that is the WHOLE recipe above... it will tend to develop cristoolite in extended wood firings..... not enough glassy phase to tie up the inherent free silica and the silica ejection from the clay crystals when chemical water is driven off. .........
 
best,
 
......................john


Found this on net...

"........If feldspar is present in the body then any available molecular silica is taken up in the formation of silicates, and thus cristobalite does not form. If it does then it too is taken into solution. A good strategy in formulating a body is to use enough spar or naturally fluxed clays to be sure that any potential cristobalite is drawn into body glass (check with dilatometer test) and then re-establish fit with fine quartz. In this way quartz is compressing the glaze at 573C rather than cristobalite at 220C. A typical cone 10 porcelain with 25-30% feldspar will show no evidence of cristobalite on its expansion curve (as measured in a dilatometer). Conversely, high iron often non-vitreous stoneware bodies can generate high cristobalite levels........" (Hansen, T. (2008). Cristabolite. Retrieved from http://digitalfire.c...istobalite.html)

After reading your post John, and more time on net, and my notes. I went off a tangent from the 70/30. Here is my attempt at a flashy body for woodfire, yet stable at lower temps. And pictured in a previous post. (Also inspired by ingredients on hand)

Gold art 55
Saggar. 15
Helmer. 11
Lizella. 5
Feldspar. 9
Nepsy. 5
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#57 neilestrick

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Posted 04 October 2013 - 09:48 AM

Also was told it performs well at cone 6 ox electric and loved almost all glazes. It's cheap, performs well across broad spectrum of temps and glazes....

 

If it can handle several days in a wood firing, it will be way too loose at cone 6.


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#58 jrgpots

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Posted 04 October 2013 - 08:34 PM

I have followed a few threads about water in the clay making.....some say rain water only. Others say distilled is best. Could you use tap water that is run through a filter removing chlorine, some Na and K ions? What type of effects would using reverse osmosis (RO) filtered water create, since the RO system removes all ions? Does it make much of a difference?

Jed

#59 Biglou13

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Posted 04 October 2013 - 09:51 PM

I can't say from a ceramics chemistry point. But all those impurities in water are very very very minute. Municipal water systems are relatively clean, I doubt that tap vs ro vs distilled vs rain would make that big a difference in clay body. I'm not doubting there is some effect, or affect on the clay. But I think there. Are bigger fish to fry, when it comes to clay bodies.

It's h2o also what is locally sourced. In pre modern society they used what they had. Sure I'm using manufactured clays, much of it local, but I have to draw the line worrying about water. Many around primary water sources are wells. I plan on using well water for my next clay. Actually there is a spring near the studio, sulfur smell in water. John b. Spoke about local clays in japan. I think it's these subtleties that make the beauty in a clay body. Kind like bread or bagels in newyork city. People say it's the water. On anagama-west website there a recipe where they tried to replicate shigariki clay at a chemical level, while the clay was functional, it was a failure in replicating.
I m hoping my local water adds flavor to my clay
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#60 Biglou13

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Posted 14 October 2013 - 09:13 PM

inspired by ingredients on hand looking for a flashy woodfired clay body.....

Gold art 55
Saggar. 15
Helmer. 11
Lizella. 5
Feldspar. 9
Nepsy. 5

Any opinions to from any of the gurus of clay...... Or anyone?
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