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Commercial Clay Reviews: PART 2

Updated: May 10

The world is severely lacking in clay reviews. Sure, there's the occasional vague Reddit post from five years ago. And then there's a couple of archived encoded posts from 2001, discussing some classics like Frost porcelain, or Standard 257. So if you're reading this, please comment IN DETAIL your experiences with clay bodies, so for the sake of humankind we can make better informed decisions without suffering the consequences of spending $85 on a new clay body on blind faith alone!


SHEFFIELD POTTERY #92700 CONE 9/10 PORCELAIN WITH MOLOCHITE GROG


Their website description: "Cone 9/10... This domestic kaolin porcelain with Molochite Grog is a very plastic and workable good throwing body. The addition of molochite porcelain grog adds tooth, limits shrinkage, and adds workability for hand building.


It's also suitable for hand-building and coil forming. It trims easily and has good dry strength.

Grog 5% White Molochite

Color In Oxidation: White Color In Reduction: Slightly Gray

Shrinkage c/9/ox. 14.25%

Absorption c/9/ox. 0.00%


My experience

Sheffield 92700 porcelain with NO glaze

  • How does it feel? The clay is firm, and tight. What do these terms even mean? What I mean is that, even when the clay is on the wetter side, the clay sticks to itself rather than create a sticky mess. (I experienced that with the Troy Porcelain from Standard.) It also means that even when throwing with a lot of water, it didn't become soup.

  • I am able to throw with less water, compared with the Standard brand clays.


  • The Sheffield clay is less creamy than the Standard brand clays. The Sheffield porcelain is smooth in that there aren't noticeable groggy particles, but there is a sandy/ toothy feeling. This allowed me to throw a lot taller, and it didn't sag as badly in the firings.

Sheffield 97200 cone 10 reduction with white glaze

  • It trims well without becoming loose and fluffy, which can happen when clay is too wet while attempting to trim. This happens when I try to trim the Standard brand clays. It doesn't happen with the Kentucky Mudworks either.

  • It does have high green strength. What does that mean? It means that I can handle it with little risk of warping, denting, and scratching, at the leather hard and bone dry stage. Compared to Standard cone 7-10 white stoneware #130, which does tend to warp/deform more easily during handling. If I were to accidentally put the Sheffield porcelain greenware down on a table top with force, or if it was put in a cardboard box tightly between other pieces, it probably wouldn't break as easily compared to a traditional grolleg porcelain. Don't you love my descriptive examples?

  • The color is a concern you are looking for white, or clear glazing. It is very stone grey in reduction when gas fired. In the first photo (octopus pitcher), there is no glaze at all on the exterior of this pieces. There is only black underglaze, and then the bare clay which looks very gray. Gold luster accents. Due to the combination of the clay body and the reduction atmosphere, the naked underglaze has a graphite quality, with a metallic sheen and stony surface.

  • In the second photo, the Sheffield porcelain is gas fired in reduction with a satin white cone 10 glaze. The glaze itself contains a few speckles, not the clay body. Notice how it is not a bright white effect, and the stony cool grey color still comes through the glaze. This is neither a good nor bad thing, just something to look out for if you were expecting bright or warm whites.

Overall, I love throwing with it, and throwing large. The glaze results were okay.



#113000 Ben's Mix White Stoneware Clay For Wood Fired Kilns from Sheffield Pottery


According to the website, " Ben's Mix White Stoneware: Porcelain / Stoneware a new Helmer kaolin based clay body which is showing exceptional results in wood firing at cone 10+. Fluxes ash nicely so it looks fantastic unglazed or with Shino in reduction."


"It has a little stoneware clay but much more of the air-floated kaolin so this body throws like a porcelain not like a stoneware.

It's not quite as short as a pure grolleg porcelain but still very little tooth.

Expect porcelain-like shrinkage.

It has great flashing results in wood because of the high percentage of Helmer.

This clay is not recommended for beginners"

****No information given about shrinkage, absorption, and color description (which I would describe as a cool grey/buff).****


Then, there are beautiful photos of UNGLAZED wood-fired pieces made with this clay. They're all bright and amazing with tons of gloss and flashing. Lol.

Unfortunately this was not my experience.

Sheffield's Ben's Mix stoneware/porcelain wood fired. No glaze on exterior

DISCLAIMER: I know how wood-firing results can vary greatly due to shape and size of the kiln, the type of wood used (yes, I am familiar with the different mineral compositions of pine vs oak, etc), the heat work, the air flow... All of those factors can be different every single time. Which is why I would LOVE to hear and see photos of other people's experiences.


MY EXPERIENCE

  • minimal to no flashing (compared to Standard's Troy porcelain when fired in the SAME wood firing kiln)

  • Very hard to throw with. Stiff, hard to center, and cracked easily.

  • "Not for beginners". That's already a red flag to me. I am not a beginner and I've had many more issues in general with this body than any other cone 10 clay body, including Sheffield's 92700 (which I liked), Standard's 181, Standard's 182, Standard's 130, Standard's Troy.

  • Seemed to trap more of the smoky and carbon-like effects rather than flashing. I am saying this as a general statement for ALL the pieces made with the Ben's Mix clay, versus all the pieces in the SAME kiln made with the Troy. So I'm looking at a range of about 25-30 pieces that were placed throughout the kiln.

NOT SHEFFIELD: This goblet is Standard's Troy porcelain fired in the same kiln as the Ben's Mix, NO GLAZE exterior except for slip marks
  • The description says it should throw like a porcelain but I disagree. It felt nothing like porcelain and every bit like a white stoneware: in the toothiness, the color, and the weight.

  • Even thin pieces weighed considerably heavier than similar pieces thrown in a different clay body, wood fired or not.

Overall, it ended up having a smooth finish which can be nice, but it was lackluster and didn't live up to the expectations. I am open-minded to hearing about other people's experiences, and I'm sure in different firing methods, or even different glazes, this clay could yield different results. If you have personal experiences and photos of this clay, please show us!





STANDARD V.P PORCELAIN #551


Online description: "Very plastic white porcelain. Good for throwing. Does not contain ball clay.

Cone 6 Average Shrinkage 13.0% Absorption 0.3%"


Great, we know nothing. So here's my experience:

Standard VP 551, clear glaze over blue slip
  • A creamy, warm white color. Not as bright white as a "real" cone 10 grolleg porcelain.

  • Very smooth (as in no tooth at all) and soft, so that even when it's stiffened up, the thixotropic qualities allow it to feel very mushy without the addition of water

  • Can get soupy quicker than white stonewares such as Kentucky Mudworks and Standard 182.

  • You can get height better than the Troy porcelain and the Kentucky Mudworks (which seem to distort or drag easily).

  • It can dry unevenly. I haven't had this problem in my studio because I let everything air dry. See, all other clay bodies dry pretty evenly all around. This clay was sensitive to placement in my studio and would warp in the shape if one side dried faster than the other. Again, this will happen to any and all clays to a certain degree, I just notice it happens much more to this clay than others.

  • I still really enjoy using this clay. It's not fussy, it's bright, and it can give a lot of elegant shapes, especially when trimming and refining.

standard vp 551 cone 6 porcelain with clear glaze and underglazes
  • It has proven to be rather forgiving, especially if you begin throwing on the stiffer side (it softens as you work, so be wary of water usage). Don't hurt yourself, of course, but starting off stiffer with this porcelain really allows for more ambitious shapes. This is not true for every clay (would NOT recommend starting stiffer with the Kentucky Mudworks Brown Bear and the Standard Brooklyn Red.)

  • Just for comparison's sake, I did need to use more water with this body compared to the Sheffield cone 10 porcelain #92700.





  • Fires a beautiful warm white

  • Reclaims very easily, but beware of the occasional excess silica powder/settlements in the bottom of the bucket. It's not as bad as the Standard #130 cone 7-10 porcelaneous stoneware, which is a NIGHTMARE to reclaim.


SHEFFIELD POTTERY: ELAINE'S CONE 6 PORCELAIN CASTING SLIP


No description given at all, so let's assume it's similar to the Elaine's cone 6 porcelain moist clay body. The description for that is:

"Cone 4-6

A high temperature Grolleg porcelain clay body. It has excellent plasticity for throwing and can be used for hand-building as well. Exceptional purity and workability combined in one body.

Grog:No Color In Oxidation:White

Color In Reduction:Blue White Shrinkage c/6/ox. 14.50%

Absorption c/6/ox. 0.00%"


MY EXPERIENCE

  • Very creamy and bright white in color

  • dries extremely fast, and thickens extremely fast in the plaster mold

  • becomes powdery very easily (see photo below)

  • Indoor environment was around 55 degrees F, moderate humidity.

  • poured in for 12-13 minutes made the cast about 1/4 inch thick. This was too thick and heavy

  • poured in for 7-10 minutes made the cast about 1/8 to 3/16 inch thick

  • green strength is only moderate, and because of the quick drying rate, it crumbled easily and did not leave much room for workability. This is standard for grolleg bodies. If you tried to rewet it after it had become quite dry, it may break into pieces. I am saying this in comparison to the next slip I used (a cone 6 stoneware)

Elaine's cone 6 porcelain casting slip
  • At first, there was cracking in the pieces because it shrunk and dried so quickly in the mold. This required me to keep the pour hole covered so that the mouth wouldn't dry faster than the body, which prevented most of the cracking from happening again, so that was generally resolved.

The insanity of 14% shrinkage
  • The positive thing is that I was able to get the cast out within 2.5 hours, consistently when casting consecutively. This is important for someone who wants to cast many pieces in a day. You would probably have better luck than me if you were casting smaller and less complex forms.

  • Another good thing is that it shipped in a big plastic bucket with a handle, which was clean and convenient.

  • The negative is that it was expensive, and the supplier did not have any more in stock when I tried to order more, and even asked them to confirm that they had it in stock before I placed my order, which they did. This caused me to switch brands and buy from somewhere else.

  • PRICE FOR TWO 3.5 GALLON PAILS, WITH TAX AND SHIPPING TO NYC: $186.26



Miller NS-4 Dover White Liquid Slip (2.5 gallon box)


from LAGUNA BRAND


Online descriptions: "Dover slip is a beautiful and versatile cone 6 white stoneware casting slip. Can be used for casting, slip trailing techniques, or various other surface applications including sgraffito, slip transfer, marbling, or painting.

Opulence Red Wagon on Dover Slip

Bisque Temp: Cone 06-05

Final/Glaze Temp: Cone: 6

color in Oxidation: White

Reduction: N/A

Avg. Shrinkage 11.6%

Avg. Water Absorption 0.0%



MY EXPERIENCE

I purchased three boxes from The Compleat Sculptor located in Manhattan. They had at least 20 boxes in stock, although an employee noted it was a popular product, so just call first to make sure they still have some.


The consistency is extremely inconsistent. Some boxes are watery and way too thin, others are thicker and fine. Some boxes seemed to contain way too much deflocculant. This is evident in:

  • rapid formation of a skin on the slip

  • poor mold release

  • brittle ware

STONEWARE SLIP ABOVE, PORCELAIN BELOW (note color difference)
  • very slow and thin cast, even when left in for 20 minutes, and it was only 1/8 inch or less

I was able to learn the right thickness to achieve, and I did this by including reclaim scraps back into new buckets of fresh slip, and no addition of water. I would let the scraps dissolve or soften overnight, and then drill mix it and sieve 3 times until it was smooth. Sometimes I would need a lot of reclaim, other times just a little. Sometimes!!!! I would just leave the lid of the bucket off and let it evaporate!!!! Sometimes the new boxes of slip were totally fine!!!! And I wouldn't have to adjust anything!!! DO YOU SEE HOW MANY FACTORS MAKE CERAMICS AN UNPREDICTABLE AND IRRELEVANT PROCESS!




Opulence Butterscotch on Dover stoneware slip

Pros of Miller Dover White Stoneware Slip from Laguna:

  • High greenware strength, and is durable enough for me to grab it and handle it without it deforming/ breaking

  • was not as powdery as the porcelain slip

  • better workability timeframe, in that I can carve easily without crumbling, let it dry under plastic and be assured it will remain wet for longer periods of time

  • you can spray and rewet it and it seems to hold up okay

  • cheaper

  • even though the slip is grey colored before firing, it fires an off-white, which was barely noticeably different than porcelain

Cons of this stoneware slip:

  • had contaminants and larger particles in it. Sieving it through 80 mesh 3 times helped tremendously

  • took 4-5 hours to get the casting out of the plaster mold

  • can feel very floppy if taken out too soon

  • very sticky, and does not cleanly come off the plaster surface. For example, you'll see the clay stain the plaster

  • worst thing was the inconsistency of the product in the boxes

Overall, this casting slip was fine. It just needed some time to get used to, and adjust. When fired, it looked fine and was watertight/ not absorbing any water.

2.5 gallon boxes, $42/each. $5 curbside pickup in Manhattan. Total for three boxes +tax= $142.18


If you are losing your mind slip-casting, here are the things I've learned in my five years of slip casting:

  • climate matters. Things I've cast in the summer come out in 30mins, in the winter the same mold release only after 3.5 hours.

  • The minutes needed change throughout the day. Your mold can absorb the slip for 10 minutes in the morning, but then take 15 minutes later that evening, simply due to the accumulation of moisture from previous castings, evaporation, separation in slip, how old is your mold, how old is your mother, the effects of reclaim vs fresh, and even if you look at it wrong.

  • Luckily, the slip has very rarely become "short" on me. Reclaim has always seemed to fix the issue, although I'm sure other people may have different experiences.

  • One thing for sure, is NEVER to use too much water. Use Darvan if needed. DARVAN 7 is a Sodium Poly Methacrylic Acid that is a deflocculant, causing clay particles to repel each other and therefore the slip becomes less viscous, without the need for water.

  • Check for leaks and crevices in between plaster mold sections. If you can't pull apart a mold after 4-5 hours, its because the suction of the sticky slip is holding the pieces together.

  • ^^^sometimes just putting the mold straps/ belts in different locations locks the mold tighter than other places

Nothing matters except your eyeballs, common sense, and finger tips. My eyes and fingers can do a better job than sitting around mathing when it comes to the thickness and consistency I need for the slip. Math doesn't account for rainy days when molds take longer to release.


Thanks for reading and I hope this was helpful. Please comment your favorite clay bodies and go in-depth!


<3 Michelle Wen









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