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Magnolia Mud Research

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Everything posted by Magnolia Mud Research

  1. success means Mission Accomplished.
  2. Chicken Scratch

    The following assumes that the reason for adding 'stuff' to the clay body is for decorative effects: Instead of adding grit to the entire clay body, just make a thick slip or paste using the regular clay body to which the 'chicken scratch' or any other material such as rice, crushed river rocks, metal filings, ... is added. The 'slip/paste' is then used coat the designated surfaces. Application can be by brushing, thin slabs, sprigging, pouring, etc. Compression of the applied layers of 'slip/paste' is recommended to insure adhesion to the substrate. The process allows the one to try various 'additives' to the clay body without having to deal with the forming or maturing of the main substrate of the ware being made. The 'slip/paste' can be applied selectively to areas where needed to create the visual or tactile surfaces of the design. After application of the 'slip/paste' the coating can be carved to produce sgraffito-like contrasts between the coating and the substrate color/texture. Paper resists also can produce surface contrasts. I have used this concept on cone 10 ware with high technical success using various sands, crushed iron nodules, chopped pine needles, sawdust, rice, crushed bisque, coarse fire clays, and garden dirt. The aesthetic success rate is moderate. Some forms are enhanced and others are deteriorated. Some additives I have not tried that might work are: crushed glazed ware, dried glaze lumps from left over glazes or hard pan muck from the bottom of a glaze bucket, crushed glass bottles, raisins, and chicken scratch. The main constraint is that the combustibles should burnout during the bisque step and any meltable components should NOT melt during bisque step. As the ad said 50 years ago: "Try it. You'll like it!" LT
  3. You can make one (of these 'tools') out of a soda straw by carefully cutting a nib in the end of the straw and then adjusting the distance between the two tines. The ease of use of the tool depends on the surface tension of the liquid (ink, slurry, ...) along with the liquid wetting characteristics on the nib and on the surface to which the liquid is being applied. I made a similar tool once using two coffee stirrers separated with card stock and held together with tape. LT
  4. Electric-Propane kiln conversion advice

    Agree with Neil, additional thoughts on burner auto shutdowns when the flame is blown out: When designing and operating a gas fueled kiln think about safety as well as the mechanics of the burners. Keep in mind that propane (C3) is significantly heavier than air (relative density 1.5), and will collect in low pockets and flow downhill. Natural gas (NG) is lighter than air (relative density 0.65) and rises and dissipates upwards. flammable range for NG are about 5-15% volume in air and for propane the range is 2.1-10.1% volume in air. LT
  5. Kiln Over firing

    Keep in mind that an 'empty' kiln fires differently than does a properly loaded kiln. I am using 'empty' to mean only shelves, shelf spacers, and cone packs. LT
  6. Making terra cotta bricks

    Or you can just use several layers of newsprint. The top layers stick to the bricks, the bottom layers stick to the board, and middle layers are free to move and peel away when the bricks are lifted. Cardboard and tarpaper should also work. LT
  7. Glass Transition video

    The ACerS CTT (CeramicTechToday) blog post today opens with a video relevant to glazes and the vitrified portion of mature clay bodies. It provides scientific insights via an entertaining series of analogies. Quote: Video: Glass transition concepts illustrated in humorous video Published on December 20th, 2017 | By: Faye Oney If you’re a glass scientist you understand basic concepts of glass transition, glass relaxation, and crystallization. But if you’re a student studying chemistry, physics, engineering, materials science, or glass and ceramics, initially the concepts may not be as easy to grasp. For the rest of us non-scientists, and especially right-brained people — well, let’s just say that we really do try hard to comprehend glass science concepts! http://ceramics.org/ceramic-tech-today/video-glass-transition-concepts-illustrated-in-humorous-video LT
  8. PQotW: Week 37

    You only need to have read the book LT
  9. Soda Firing Questions

    About 30 (+/-) years ago, alumina beads, similar to what you are describing, were used to remove alkali vapor species from hot gases in research pilot plants developing the technology for the production of syngas from coal and biomass to be power stationary gas turbines. The beads captured the sodium and potassium species as alkali aluminate, a reaction product of the vapor species with the alumina. Much of the work on alumina pellets for alkali vapor removal was done at Argonne National Laboratory. The important point for potters to keep in mind is that porous alumina pellets are very reactive with sodium vapor species in combustion environments at temperatures above about 600 c. The good news is that the reaction product is not a glaze, just a crystalline solid that is soluble in hot water. ANL was issued patents on an alkali vapor analytical probe based on alumina bead technology. LT
  10. Crystalline Glaze Chemstry

    Tom, well done! I am encouraged to see that someone else believes that it is possible to make good crystalline glaze application without the glaze running off the pot! LT
  11. Soda Firing Questions

    While I have no specific recommendations for the choice of refractory for cabako's kiln, I do want to comment on where to look for insights. The interior of a black liquor furnace (a industrial device used in the manufacture of paper) is exposed to similar refractory corrodents as found in a salt/soda pottery kiln. Anyone seriously studying deterioration of a soda/salt kiln should not ignore the understandings of refractory corrosion that have been published in the black liquor furnace literature. I recall reading a late 1990's paper on refractory corrosion in black liquor systems. The European electric power industry has for several decades sponsored studies on resistance to alkali corrosion from biomass combustion (again an industrial environment analogous to a salt/soda kiln environment). The answers to many of a studio potter's questions on kiln materials for salt/soda kilns are already published in the refractory and other industrial & scientific literature, but these studies will not be found using 'salt firing' or 'soda firing' as internet search terms. LT
  12. PQotW: Week 37

    3,2,3,1 LT
  13. Beginning wheel throwing projects

    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
  14. Question About a Bread Cloche for Baking

    Sumi von Dassow has written some books and CM/PMI articles on cooking pots. Check out her website for bread crumbs on this questions. LT
  15. Bottom Depth Tool

    Ron, Your wood turned form is beautiful, and ditto the measuring tool! LT
  16. NCECA

    John, The CLAYART room has been inside the NCECA location at least since 2013.
  17. Bottom Depth Tool

    I agree with Mark on the getting the "feel for this bottom thickness" from practice. Practice may not make perfect, but it does lead to consistency. As a beginner, and I found that a couple of wooden coffee stirrers from the famous coffee shop will work just like Ron's. Lay one stirrer horizontally across the bowl, cup, etc. as in Ron's and drop the other stick vertically in the lowest point inside the pot, make a mark on the stick where it crosses the top of the horizontal stick. Then do the same outside the pot so that the stick rests vertically on the bat surface (wheel if your work bat-less) and again make a mark on the stick. The difference between the marks is the thickness of the bottom. I use coffee stirrers for lots of chores and nearly always have several either in my pocket, or handy in my tool kit. I tend to evaluate the bottom thickness against the width of the coffee stirrer and estimate how many stick widths I need to remove by trimming. I then trim the inside area of the foot so that the amount removed is appropriate. Then I trim the rest of the foot. My mentor always (except when he didn't) marked the position of the inside bottom on the outside of the pot with a line of some sort. Then when the pot needed trimming this line was used to guide the trimming. Trimming is related to throwing by forming habits that get's the job done efficiently for the person doing the job. It is easy for me to trim my pots because I generally know what expect in the bowl. Trimming another potter's pot (as is often the case at bowl-a-thons) requires deliberate attention to certain steps at the right time to avoid ruining a pot. This situation is where my coffee stirrers really pay off. LT
  18. I have stainless steel table knives sharpened and reshaped into trimming tools. A spoon sharpened into a tool for cutting foot rings on tea bowls a serving spoon bent to form a chattering tool, and the 'of course' use of that thing-aha-my-jig that was originally sold to pastry chefs for making pie crusts and is now used make thin slabs of clay out of thick ones; aka the rolling pin. LT
  19. The issue with Laguna Iron Phoenix glaze...

    or maybe it just don't matter. LT
  20. single firing, cone 6 stoneware

    ... an intriguing idea ... it would require standing up, walking 25 meters from the throwing studio to the 'scrap barrel" in the glazing studio and returning without my hands drying or dripping. LT
  21. Ian Currie Test Tiles Forums?

    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
  22. Ian Currie Test Tiles Forums?

    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
  23. single firing, cone 6 stoneware

    Scrap glaze At the college we have more than 10 glazes ranging from clear through the whole spectrum to black and white, along with a barrel of 'wash water' where the stirrer is washed. Any unused glaze from testing assignments or "whatever experiments" along with leftover glazes goes into a 10 gallon barrel labeled "scrap." Scrap is constantly changing. It is used to glaze the insides of bottles and jugs. It is often used as a background coat for applying contrasting texture, color, or 'value' (light-dark) glazes over it. Even after 5 years the scrap barrel has not overflowed. We did have it go to almost empty a couple of semesters ago. Some students prefer scrap because it is always interesting . I always use the "wash water" to tint the "unglazed" areas on vases, bowls, sculpture, and foot rings. lt
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