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Magnolia Mud Research

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Everything posted by Magnolia Mud Research

  1. Magnolia Mud Research

    Kiln firing variations

    Yes, barometric pressure is an important combustion variable. High barometer readings means that there is more molecules of oxygen per unit volume of air than in air with a low barometer reading. The ratio of the two barometer readings gives the ratio of the number of molecules in the same volume. The temperature and the absolute humidity readings also effect the combustion. When the absolute humidity is high (high relative humidity AND high ambient temperature) the air is diluted with water. Said another way, you must "pump" more air into the kiln just to burn the fuel you are supplying the kiln. The absolute altitude of the kiln is also an important variable. Moving a kiln from Miami to Denver will change the way it appears to fire. Regardless of power or natural draft burners. It's all summed up in PV = nRT (a.k.a. Ideal Gas Equation) LT
  2. Magnolia Mud Research

    Terra Sig question

    I don't use TS with stains, so have no direct experience. However based on simple fluid mechanics of particles settling in water, the general situation is as follows: The density of stains and oxides added to the TS are significantly more dense than the particles of the clay and will sink much faster than the clay particles unless they (the heavy particles) are significantly smaller than the clay particles -- which in my experience is unlikely. Conclusion: The stains and oxides will always be hard to keep in suspension. I am inclined to use a high speed blender to re-suspend the materials just before using adding the "extras" to the slurry. The OM-4 TS we use at school works fine just shaking the gallon jug just before using the TS on naked Raku pieces or foot rings of bowls and cups. Given your observations, I would also try on a small sample adding vinegar, etc. to see what happens. It the treatment helps, go for it. I'd also make a backup source of pure TS for backup. LT
  3. Magnolia Mud Research

    Terra Sig question

    Dick, Once you have separated the TS from the large particles there is no need to worry about flocculation/deflocculation of the material. Just adjust the concentration of particles to the value (usually measured by specific gravity) that you like. Vince Pitelka likes 1.5 specific gravity. Direct answer to your two questions: 1. No. In still water, the visible particles will settle over time, regardless of the flocculation/deflocculation. 2. This depends on what additive is used to adjust the flocculation/deflocculation condition. Since the most common reagent is sodium silicate, or soda ash, you will be adding flux to the clay particles and will lower the temperature at which the particles become a glaze. I often dry the TS and then crush it to powder and store the powder in a candy tin until I need to make a TS. Then just let leftover dry and put back into the tin until next needed. See Vince's TS web page: https://sites.tntech.edu/wpitelka/terra-sigillata/ A very thorough document. LT
  4. Magnolia Mud Research

    Confusing Glaze Result

    Joseph, Have you fired the subject clay body without the slip and glaze, that is fired it raw, and compared it with a fired raw piece from the older bag of the subject clay body? LT
  5. Magnolia Mud Research

    Glaze or clay effect?!

    If you use a "dry powder slip" applied to a moist cylinder and compress the "dry slip" into the surface before stretching the cylinder, the sodium silicate and the heat gun is not necessary. The technique is one of many that exploits the aesthetics of contrasting areas. I often use dry clay (OM4, EPK, Red Art, Local clay) as the dry powder. LT
  6. Magnolia Mud Research

    Food safety in glazes

    an addendum to my prior post: alternative sources for: Mastering Cone 6 Glazes by: John Hesselberth & Ron Roy Publication Date: July 11, 2013 Book Size: 6" x 9" Pages: 240 Binding: Perfect Bound $24.95 https://www.thebookpatch.com/BookStore/mastering-cone-6-glazes/d2bea83c-2c34-4ed0-8a00-a6f12113515d https://itunes.apple.com/us/book/mastering-cone-6-glazes/id573583135?mt=11 $19.99 Available on iPhone, iPad, iPod touch, and Mac. Category: Art & Architecture Published: Oct 25, 2012 Publisher: Glaze Master Press Seller: John Hesselberth Print Length: 168 Pages Language: English
  7. Magnolia Mud Research

    Food safety in glazes

    Get the book: MASTERING CONE 6 GLAZES and read it carefully, not just for the recipes and pretty pictures, but for the insights on glaze stability. The book is available from various sources including iBooks and directly from the authors. Spend time on the book website: http://www.masteringglazes.com/ authors' websites: John Hesselberth: http://frogpondpottery.com/ Ron Roy: http://www.ronroy.net/ lt
  8. Magnolia Mud Research

    Glaze shivering with Penn State Shino and Rod's Bod Clay

    The name is Shino # 1. it seems to have been originated by Unknown who wrote the recipe on the 5 gallon bucket. I have no information of the source of the bucket.
  9. Magnolia Mud Research

    Glaze shivering with Penn State Shino and Rod's Bod Clay

    this is the Shino I use at cone 10. Water/solids ratio is ~0.7 weight ratio. Crackle, yes on some clay bodies. Never observed shivering. component % wt Soda Ash 8.1 Neph Sy 39.3 Spodumene 30.6 OM4 17.2 EPK 4.8 Total 100 LT
  10. Magnolia Mud Research

    Graphite drawing on clay

    Your take is what I meant. All you will be doing is drying the sodium silicate thoroughly with some possibility of chemical reactions with the substrate.
  11. Magnolia Mud Research

    Graphite drawing on clay

    Tomás My answer is No! you are not wasting your time. Graphite will burn off in a typical bisque or glaze firing. Wikipedia chatter implies that the graphite ignition temperature is around 800 C. However, it will not burn off at oven temperatures. If you fired the substrate to a higher bisque temperature than normal, but still within the porous region, the surface will still be able to capture the graphite marks and the pieces will be stronger. If you are satisfied with the strength of the available bisque ware then just draw and then coat. Finished with a thin spray coating of "water glass" (aka sodium silicate) followed by a thorough drying at oven temperatures should produce a non-smudging object. Try it. That is the only way you will know for sure. Your approach is essentially no different than the naked Raku, or horse hair Raku, or pit firing techniques where the marks are made by carbonizing. You are just skipping the firing smoke and fuss. Congratulations for thinking outside the typical pottery box. LT
  12. Magnolia Mud Research

    22k Gold Decals with positive/negative charge?

    My speculation is a combination of surface tension and static charging of the non-conductive coating and backing of the decals are the main parameters behind the observed behaviors. It would be interesting so find out what happens if a drop of alcohol (changes the surface tension) were added placed on the clusters of decals or if the water were dosed with salt (increases the conductivity of the liquid phase). LT
  13. Magnolia Mud Research

    Help with drying

    A suggestion: Make several "test" bowls at one sitting. Does not matter if thrown or handbuilt, but thrown is more informative. Cover number 1 very carefully to keep moist for a long period. cover number 2 very lightly cover number 3 more than lightly but not as much as for long storage. cover number 4 more than 3 but less than 1 cover number 5 more than 4 but less than 1 ... etc until you run out of space or get bored. Put the pots on your shelf and check them first thing every time you go to the studio. Evaluate how moist the pot is relative to trimming or making attachments, and other needs. Don't stop the experiment because of cracks; a cracked pot can still tell you a lot about how it dries. Recycle later after you get the drying information. After a few inspections over time you will have a fairly good idea of how to cover your ware between scheduled sessions. Pay attention to the weather -- temperature, humidity, wind, and the AC in the studio -- as these characteristics of the immediate environment at the pot storage are important. Keep notes and use them to guide your decisions. Also learn the technique of trimming dry pots as mentioned by oldlady. LT
  14. Magnolia Mud Research

    Choosing Glazes

    Ms. E, Take a good look at John Post's website. http://johnpost.us/ I don't remember exactly where on the site he discusses his 'system' for the glazing of his student's work, but he has a very effective system that resembles the situation you have described for your workshops. LT
  15. Magnolia Mud Research

    Advancer Shelves: kiln wash or not?

    I'd bet that if you put a coat of OM-4 terra sig on the bottom of the porcelain that the feathers would not need plucking.
  16. Magnolia Mud Research

    reclaiming glaze

    As the old Alka-Seltzer ad said: "Try it, you'll .... it" I see no reason it should not work. Assumptions that come with such reclaim: The solubles in the glaze recipe are negligible. The ink, and any other stuff picked up, from the newspaper will burnout clean with no metallic residue. The rehydrated solids will easily stay suspended at least as well as the original glaze mix. Your handling of the reclaimed powder does not provide any contamination. I would make a reclaimed batch, test it on a test piece to confirm that it remains clear and meets your specifications. If it passes muster, then use that reclaimed batch. LT
  17. Magnolia Mud Research

    cracking bottoms in the kiln

    EPK = kaolin
  18. Magnolia Mud Research

    No glaze over underglaze?

    Are the pieces fired to maturity, that is until the water absorption is essentially zero? The porcelains I use at cone 10 fired without glaze do not absorb oils. LT
  19. Magnolia Mud Research

    White marks on Final Pieces

    Yes, you can refire to a higher temperature. You might talk to the clay supplier about the color changes as the firing temperature is increased. My suggestion is to make several 'test pieces'; small - say the size of your fist. Fire each one to a different higher temperature; this will give you information of the surface appearance after firing. Then on the basis of the testing, you can choose the firing temperature for your initial piece. From another approach, there are lots of ways to treat the surface of sculpture. Many of my sculptural pieces are intended for controlled environments (kept in the house or barn) and after the bisque firing, the pieces are rubbed with a thin coating of raw moist clay - different naturally colored clays provides a palette similar to earth-tone chalk used in drawings. Applied carefully, the surface does not flake. There are many 'dry glaze/stain' alternate approaches (relative to glazes, etc.) for sculptural ceramics. LT
  20. Magnolia Mud Research

    White marks on Final Pieces

    The important question is what did you plan to do after the bisque firing? What finishing technique was planned? If the piece was to be stained or glazed and fired to a higher temperature, go ahead and do that. If the bisqued firing was intended to be the only firing, then the issue of surface color of the bisque may be more than just an educational artifact. I have noticed with some bisqued clay bodies that washing of the bisque ware with tap water and allowing it to dry will change the surface color somewhat. Don't know why. LT
  21. Magnolia Mud Research

    gas kiln.

    Sometime back, in a Clayart posting, Mel pointed out that all you need to do is to count the bricks in the drawings from CM article or the 21st book. For more info go to Mel's Website: http://www.melpots.com/ and email him about building your kiln. LT
  22. Magnolia Mud Research

    Drying chamber

    Dan, Do an internet search for "wood drying cabinet" or something like that. There are lots of versions that will work. My approach has been this: Make a tent from a plastic drop cloth with several small (40 watt) light bulbs at the bottom where the air will come in, and have a hole at the top to exhaust the moist air. You will need to provide some forced ventilation for the room that contains the "tent" so that the moist air does not recycle back into the tent. The light bulbs will heat the air and the warm air will rise. As it rises it also provides the energy (heat) to evaporate the water from the clay. You can control somewhat the relative humidity in the tent by keeping an open container of water at the bottom of the tent. Vary the area of exposed water to make adjustments. It is a "trial and error" approach to control but with some patience you can make the system work for you. The number or size of the light bulbs sets the energy input. The sizes of the entrance and exit of the "tent" along with the temperature differences between ambient and the "tent" insides will be the other major handle for control. LT
  23. Magnolia Mud Research

    Black speckles in porcelain - sand?

    I have done the same thing, except I use the red sandy clay from the bottom of my Texas ponds (or from the bank of the pond when the pond is full). Dry the clay/sand; then crush the dried stuff with a mallet, and screen through a kitchen strainer. Throw the big lumps back in the pond and use the fines. Wedge into wet porcelain using slam-cut wedging technique and have a go. I add some where between 1 or 2 cups of dry clay/sand into a block of porcelain that is about 4x4x8 inches. If you don't have a pond, use the red sand from you nearby garden supply center. LT
  24. Magnolia Mud Research

    Any Wood/Salt kilns near Austin, TX?

    Josh, Visit Armadillo Clay in Austin and ask them. Also chat with the ceramics department at UT-Austin.
  25. 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

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