Magnolia Mud Research

put six-by-twos under the seat, or use the phone book on the seat, that solved the problem of the low level chair at the dinner table when I was a kid. LT

well, PT Barnum didn't think so. My perspective is that the customer controls of what is bought, while the supplier controls what is offered for sale.

Pres, There is a lot to be said about the 10,000 hours of practice ... . I don't remember the rest of the story. Practice not only of throwing, but designing work that is interesting and desirable. Well thrown pots can be ruined with poor choices of glaze and glaze applications. 40 hours practice per week leads to about 5 years of practice (+/- a year or so). LT

According to my memory, there is a paragraph or two in Val Cushing's handbook on clay bodies for use in cold climates. Fully vitrified porcelain is not one of those clay bodies, as I remember; there is a optimum porosity for freeze - thaw requirements. Also check the Rhodes & Hopper book on clay bodies. Remember that roof tiles and bricks have been used in cold and snowy regions for several hundred years and they have survived lots of freeze thaw cycles. LT

About 10-15 years back (+/-), there were Clayart discussions on reduction in electric kilns. Mel Jacobson discussed his conversion of a small electric kiln to fire in reduction; Lee Love and John Baymore both discussed how the Japanese were routinely using large electric kilns for reduction. From what I remember from these discussions the customer base for electric reduction kilns is unwilling pay the cost of a well designed electric kiln for controlled reduction. As a point of comparison, the heat treatment industry routinely uses electric furnaces for controlled atmosphere treatments of various metals where the atmosphere is in what a potter calls 'reduction'. LT

I don't know for sure when I learned to throw clay, but it must have been about the time I started first grade at school. A new house was being built next door and my dad allowed the neighbor to level some of the hill we lived on. The part next to the house was a hard yellow clay and that was the material I learned to throw with. Took only a couple of days, with my dad as a teacher, to learn to throw straight. (I also learned to bat the clay 'balls' thrown at me). By high school time, I had given up throwing clay and was more interested in chemistry and engineering. Resumed my clay throwing around '05. The biggest difference now is that the clay is softer; back when I first started clay was always thrown dry; now the throwing clay is always wet, soft, and sticks to the bats.

My current fad is the use of soda ash, twenty-mule-team Borax, and TSP solutions sprayed on to raw clay surfaces - especially surfaces created from dry clay embedded in the moist surface of a clay body prior to the surface being stretched. Firing is cone 10 gas kiln.

Art is in the mind of the observer. During the creation of an object the maker is the primary observer. After the object is completed and released, the decision regarding the "artness" of the object is determined by the observer. Different observers may (will) have different decisions on the placement of the object in the art ---- non-art spectrum. The debate within the ceramic "art" domain between art and functional ware is a contrived debate. All ceramic articles have a function even if that function is to just take up space. The observers, owners, users, ... are the decision makers as to the specific functionality of the object. My tea mug has multiple functions. At this moment its (the mug) function is to keep a fan from blowing paper off the desk. The sculpture across the room functions as both a hat rack and a source of inspiration until I put on my hat and go to the studio, then its function is to be a piece of burnt dirt taking up space and keeping the table from drifting off into the ether while it waits for someone to return and take notice! LT

Pres, Recipe for wadding box: Start with a big C-clamp, or a big Double Anvil C-Clamp, or something like IRWIN QUICK-GRIP 0.75-in Clamp, some scraps of 1x4 and 1x6 planks, some nails, glue, etc., your own creativity, and you can make one of those wadding boxes your self. LT

cloth towels (dish towels or bath towels) for cleaning hands while throwing or using clay slips; paper towels after washing hands, sponge to clean tables and shelves, don't pull handles (my mugs have built-in handles)

Clay toys The ceramic I class has frequently required a ceramic toy (~90% ceramic) as one of the final assignments. Students have made dolls, pinewood block derby type cars, checkers and chess sets of all sizes (one chess set used Raku pieces about 6-8 inches tall), jigsaw puzzles, dice, rattles, dominoes, blocks, and some other toys I don't remember. Some were glazed, others were finished with acrylic paints, and some were left unglazed. Many were just fired to bisque and then finished with paints and stains. The assignment was especially challenging to the students that thought only traditional function ware was pottery. The Ceramics II class had a similar assignment, usually early in the semester, called the trompe l'oeil assignment, which in my mind is a sophisticated version of the toy assignment. I had a classmate sometime back that worked with miniature cups, saucers, tea pots, bowls, bottles, etc. all less than 1 inch in size, all wheel thrown. She sold them at festivals for dollhouse ware. I have made fortune cookies, apple popovers, dice, puzzles, tic-tat-toe boards and a bowl of grits; some were fired to only bisque, others fired to cone 10, with either oxide staining, burnished clay, or raw clay as surfaces. The aesthetically successful ones were gobbled up at the club sales, the not-so ones become road rocks. I'll look around the storage cupboard and see if I have any pieces left for photos - don't hold your breath. Making toys requires an additional set of skills besides those of just manipulating clay. Toys are expected to be "toyed with", not just become decorations on a desk or in a cabinet. Therefore, the toy must also be functional and robust enough to be used as a toy. The ceramic pinewood derby car required several tries before the student got the weight balanced and the wheels and axles aligned in three dimensions. He learned a lot about making stuff from the assignment. LT

Backfill is an aesthetic detail and is used to avoid an abrupt "end" of a line. However, I always compress and round the transition from the handle material and the object material using the side of a 3mm diameter skewer so that there is smooth curved transition from the handle to the mug. Sharp (acute angle) corners are stress risers (in mechanical engineering jargon) that often lead to the origin of cracks in drying and firing. Rounding these joins reduces the likelihood of cracks. When examined up close, both of the illustration cups in Callie's post have this rounded transition at all of the joins; yet the blue cup handle seems to lack the general flowing lines of the handle on the white cup. LT

I follow the concept in this quote from Chuck Close: “Amateurs look for inspiration; the rest of us just get up and go to work.” Chuck Close ( https://www.goodreads.com/author/quotes/166434.Chuck_Close )

The warping of a particular ceramic object should be related to the gravitational forces of the object and the thermal effects on material strength (aka softening), so how will adding a "waster" (which I understand is just a slab of clay between the ware and the kiln shelf) prevent warping? LT

Several recent posts got me thinking about how to search for information on a topic of interest, therefore: Where do you go to obtain more information (and/or background) on ceramic related topics, ideas, suggestions, insights, or questions you pick up from colleagues, general reading, online forums, in casual discussion, or your own pondering? How do you approach searching for information? Where and how do you start? What do you do when your first internet search turns up essentially nothing? How do you evaluate the "correctness" or "reliability" of the sources you use? Are certain sources more reliable that others? Does the reliability of a source depend on the nature of the information you are seeking? Are older sources more reliable than younger sources? How do you resolve conflicting information in your search for answers to your questions? LT

2,3,3,4 tentative, until the library delivers the book. lt

Callie, I'll take a stab on why this procedure works to produce copper reds in an oxidation kiln: The iron oxides and powdered charcoal provides a oxygen fugacity buffer where the dominant carbon gas form is carbon monoxide (CO). The CO reacts with the copper ions in the glaze to reduce the copper to the copper specie that produces the red colour. I haven't done the calcs, so consider this as an SWAG. Your question would make a good exercise for a Geo-PChem exam. LT

1: 3 2: 2 3: 1 4: 2,3

You know you are not meant to be a potter if ...... You are more excited by the details of a process or technique than the pots you make using these skills. See Tony Clennell's posts over the last month: http://smokieclennell.blogspot.com/2018/02/confession-im-not-potter.html LT

nerd, Based on your statement: "Even when I slow down, pay very close attention, still pull the top of the cylinder slightly off and open," and my observations of many students (including myself) I am guessing that you are pulling your hands of horizontally from the top and you are moving them rapidly while the wheel speed is slow. If so, the most likely cause is the surface tension between the clay and your hand - usually the fingers. The corrective action is: move your hand away from the clay surface slowly to allow the wheel to rotate several times as you move your hands off the clay. LT

Joseph, Good ideas worth consideration. I use the Currie tile as a quick technique to cover a wide range of composition(s) for the purpose of 'zeroing in' to a range that will justify detailed effort. My preferred glaze test tile is an inverted "T" with stamped details similar to what I use on my work. These are extruded (about 3-4 inch tall inverted "T") and cut to about 1.5 inch wide (wet). These are used for line blends over a narrow range. Yes they may take more kiln space, but their purpose is different than the Currie tile. Also the narrowed line blend needs less tiles therefore less kiln space. I also work on one glaze at a time. LT

Currie grid tiles I prefer stretch-throwing slabs followed by compressing and smoothing the surface with a rolling pin or a squeegee. I then place a tar paper template on the tile, trim the outside dimensions, and make the indentations with a purposely made stamp - currently the end of a broken tree limb shaped into a square. The stamp provides some texture that helps evaluate the 'breaking' tendency of the melt. Making a tile takes less than five minutes start to finish and only needs about 18 inches of work space and nearly zero of storage space for the template and stamp. The stamp is then available for other decorative effects. I have thought about making a wooden drape mold, but it requires ~40 individual stamps and a lot more storage space. After a making a few tiles it is easy to estimate the correct amount of clay needed for a tile. A good starting amount is by volume: V = width x length x thickness in cm. Take that amount of soft clay and make the flat smooth tile. My tiles are about 16 x 26 x 1 cm and I start with about 15x15x2.5 (cm) chunk of clay from the bag and wedge it into a cube before starting the stretch-throwing technique. When there is not sufficient space to throw, I just use a mallet to 'beat the clay into shape'! LT

Actually the author is Tom Turner.

Pieter, Pieter Mostert Posted 06 August 2017, 02:21 PM "I'm afraid my knowledge of glass and glazes doesn't expend that far. Do you have a reference where I can read up on this?" Here is a quickly developed list of sources that might be useful: Mysen, Bjorn, & Pascal Richet. "Developments in Geochemistry 10, Silicate Glasses and Melts - Properties and Structure" Elsevier, 2005 (ISBN 0444520112) This book covers just about everything. *|* Shelby, James E. "Introduction to Glass Science and Technology 2 ed." Royal Society of Chemistry. (ISBN 085404639) *|* Lecture notes from an introductory college course on glass for ceramic engineering students: Structural Theories of Glass Formation http://web.mst.edu/~brow/PDF_structure1.pdf http://web.mst.edu/~brow/PDF_structure2.pdf *|* Notes and reading topics for the 2013 online course "Atomistic Modeling of Glass Structure & Glass Properties" pre-lecture readings: http://www.lehigh.edu/imi/teched/AtModel/Lecture_3_reading_geochematerials.pdf http://www.lehigh.edu/imi/teched/AtModel/Lecture_3_reading_structure_silicate_glass.pdf http://www.lehigh.edu/imi/teched/AtModel/Lecture_3_Assignment_Micoulaut_Atomistics_Glass_Course.pdf the formal lecture presentation: http://www.lehigh.edu/imi/teched/AtModel/Lecture_3_Micoulaut_Atomistics_Glass_Course.pdf *|* A presentation from: GEO-RAMAN Xth MEETING 11-13 JUNE 2012, Nancy (France) sponsored by European Mineralogical Union (EMU) title: Raman Spectroscopy of Silicate Glasses and Melts in Geological Systems presented by Stephanie Rossano & Bjorn Mysen http://georaman2014.wustl.edu/previous/2012/georaman10.uhp-nancy.fr/planchesInternationalschool/015%20SilicateGlassesAndMelts-S-Rossano.ppt.pdf *|* The applications of glass and the structure of glass from molecular dynamics seminar notes presented by Dr. Gavin Mountjoy, University of Kent, Canterbury, UK http://www.kent.ac.uk/physical-sciences/staff/profiles/gm/MD_glass_seminar.pdf *|* My experience has been that the details of the physics and chemistry of silicate melts (aka "glazes" in studio potter lingo) is discussed best in the domains of igneous petrology and materials science disciplines. The Seger model is not wrong so much as it does not account for about a hundred and twenty years of progress in understanding the structure of a silicate melt at the atomic level. Both models just count species and use the ratios of species as variables, but the most recent models do a better job predicting physical and other properties than Seger's model. Currie's scheme of a grid test is a very useful technique; the scheme provides a large amount of data in a small package that almost eliminates the position in the kiln variable associated with individual test tiles; and the scheme can be applied in a way to minimize the leftover glaze(s). LT

Curt was asking about what appeared to be "counterintuitive to me because I see iron as a flux". I suggest looking at the non-bridging oxygens per tetrahedron for the melt (I haven't done the calculations) for each tile. It could be that the iron is allowing the aluminum to become a network former by charge balancing. The Fe to Al atomic ratio may also be an informative variable. LT