Jump to content

Magnolia Mud Research

  • Posts

  • Joined

  • Last visited

Everything posted by Magnolia Mud Research

  1. 1. The 10-12% sugar was added to the 100% of the other ingredients and is not a ratio of sugar to cement; put another way, to 100 grams of the glaze components I added 10-12 grams of sugar. Since it worked, and was a "let's see if this will make an interesting glaze" project and the slurry remained OK, there was no incentive to optimize. I was interested in the fired glaze, not the recipe. The glaze was a beautiful clear over a low iron stoneware; with a pinch of cobalt it make a nice blue. 2. My mixing process was to estimate the amount of water needed based on the true volume of the solids and use a volume ratio of water to solid volume starting point around 0.6. the solid ingredients are added to the water with vigorous mixing in this order: solubles, mix, clays next, mix, light rocks, mix, and heavy rocks last, mix; add a little more water (with vigorous mixing) if the slurry is too thick, and a final vigorous mix. The glaze is ready to use. for the cement glaze, the sugar was added to the water first. Yes, this is NOT what the standard studio textbook teaches ; it is how I was taught to put solids into a slurry (but then, ik ben een chemisch ingenieur). 3. A long range problem with Portland cement as a calcium source for glaze is the storage time of a bag of Portland cement is short, on the order of a few months; once the bag is opened, moisture migrates into the bag and the bag becomes a big lump. LT
  2. I don't remember there being any "rotting" or "stinking" in the container that set in on the shelf for several months after my testing placing a stick of bare copper wire in the container will be a deterrent on "rotting and stinking". LT
  3. The project began from a very early CM magazine article using Portland Cement (PC) [a mixture of tricalcium silicate (3CaO · SiO2), dicalcium silicate (2CaO · SiO2), tricalcium aluminate (3CaO · Al2O3)]. LT
  4. @Piedmont Pottery @Callie Beller Diesel @Min sometime way back I was working with some calcium silicate materials as part of a glaze research project. The problem was how to prevent the calcium silicates forming "concrete" from the glaze slurry sitting still for several days. The answer came from a Professor researching concrete; very small amounts of sugar are often added to the concrete mix when the pour is more than an hour from the mix station to the pour sight; using that data, and a SWAG adjustment from a an hour to "forever", a 10-12% sugar level (of the glaze solids) was arrived; the two gallons of glaze slurry with 10-12% sugar was still just a slurry (settled as soft and easily stirred without needing screening) after a several months setting in the glaze room. LT
  5. mica is possible, but so is a white grog made from high fire kiln wash (alumina+kaolin) added to a red or dark clay body, or grog made from bisqued high fire porcelain. I have used crushed fired dry kiln wash mixed with red clay in a surface slip and get similar contrasting effects for coatings. LT
  6. two articles addressing spray equipment is available on Vince Pitelka's website: https://vincepitelka.com/wp-content/uploads/2019/03/Spray-Equipment-and-Compressors.pdf https://vincepitelka.com/wp-content/uploads/2016/03/Using-the-Gravity-Feed-HVLP-Spraygun.pdf My experience with spraying glaze requires a slurry that is "less viscous" than dipping/pouring glaze slurries, which generally means more water and lower specific gravity. Also remember to always stand upwind of the ware when spraying. LT
  7. Functionality of anything, and especially ceramic art/pottery items, is determined by the user, not the maker; regardless of the maker's intent! A large ceramic vessel designed and manufactured to separate butter from fresh milk is functioning as an umbrella stand. A heavy cylinder of fired clay (closed on one end) is functioning as a paper weight one day; a pencil holder the next day, and recently was functioning the amount of epk going into a batch of glaze, and the when the rain stops will be functioning by holding a window partially open! meanwhile its function is to hold down the table on which it sits so that the table does not float to the roof of the building. I know of a large collection of ceramics items that functions only to fill the space in the corner of a brick building awaiting an opportunity to function in a different way. Yes the use of the word "functional" for ceramic items is ambiguous, but As "The Eagles" says in the opening track of "Hell Freezes Over": "get over it!" LT
  8. a lead article in July 2021 issue of Industrial Heating magazine: How Long Should My Thermocouple Last? https://digitaledition.industrialheating.com/july-2021/how-long-should-my-thermocouple-last/ yeah, the author is focused on commercial applications and the examples are not pottery kilns; however, the discussion of the corrosion of the thermocouple and the protection tube however is generic and does address some important insights not often mentioned in the studio pottery discussions. LT
  9. switch from "hump" molds to "slump" molds; thin use the half-dome steel forms; the clay shrinkage will pull away from the form without cracking. coat the form starch. has worked for me using glass, metal, and "found object" forms. LT
  10. Dianna I have used low fire clear glazes from Amaco (and several other brands) on clay bodies fired to cone 3, to cone 5, and to cone 10 in a gas kiln without problems. The cone 05 maturity for these low fire glazes are slightly above the bisque temperature of these clay bodies; this means that the clay body acts as a sponge for the melt and soaks the glaze. Try it, and see what happens on your clay, the way you apply the glaze, and the way you fire your ware. plan on using cookies until you are determine cookies are not needed. Always remember that thickness of the glaze application is important; thicker often means running. Glaze "fit" may be a bigger problem than running. LT
  11. I’ve used Corn Huskers Lotion in the studio for a long time; it has no oils, don’t smell, does not act as a glaze resist, and is compatible with ceramic materials.
  12. keeping the "shed" cool enough to prevent combustion of the "shed" is important; equality important is to keep the controller of the electric kiln cool enough to properly control the firing; that temperature is likely to be lower than the safety fire protection temperature of the building. LT
  13. I have used watercolors on bisque ware followed by glazes. Treat both as if you were making a watercolor painting. adding some soluble organic material that will act as glue when dried can also help: skimmed milk, sugar, clear water color medium, ... I have used clear acrylic and cobalt blue acrylic paint on both greenware and bisque ware and the acrylic does act as a repellant to water based glaze. Mixing the clear glaze into a clear acrylic would probably work, but why go that route? cobalt acrylic paint does work on both greenware and bisque, but the bonding is poor unless something similar to baking soda added to the "paint' to assist in the low temperature bonding when firing. Keep tinkering with the materials. LT
  14. Vince Pitelka wrote about his homebuilt pugmill: https://vincepitelka.com/wp-content/uploads/2016/03/Building-the-Harry-Davis-Pugmill.pdf The "motor" can be any device, hand cranked, water fall, windmill, etc. I recall reading years ago about using a hand driven sausage grinder for small amounts of clay. a pugmill is just a tough version of a bread/cake mixer. clay mixing has been around a lot longer pugmills. think outside of the standard box and improvise! LT
  15. my first and second choices: #1 "The Craft and Art of Clay" by Susan Peterson; any after edition 2. #2 "Hands in Clay" by Charlotte Speight & John Toki; I have edition 5, any are good art ceramics. For sound science: the engineering textbook "Introduction to Ceramics" by Kingery, Bowen, Uhlmann; second edition. LT
  16. @Rick Wise @neilestrick the IUPAC (International Union of Pure and Applied Chemistry) has the "official" meaning of the terms "flocculation" and "deflocculation" see: https://doi.org/10.1351/goldbook.A00182 flocculation https://doi.org/10.1351/goldbook.D01555 deflocculation https://www.degruyter.com/document/doi/10.1351/pac200779101801/html the document for the official definitions of the terms. see pages 1820 & 1824 logic also implies that something can't be deflocculated until it has been flocculated and vice versa. LT
  17. Try 1 part iron oxide plus 1 part frit (which ever one you usually use at low fire) plus 1 part bentonite or equal parts iron oxide plus gerstley borate. Test it and see if it's doing what you want, dilute or increase the iron or frit/gerstley borate as necessary. BTW, cone 4 is roughly 1160C so thinking you meant cone 04 which would be roughly 1060C. I use a mixture of iron oxide and water as an ink for my logo on greenware. the bisque is fired to ~cone 07 (~950 C) and the marks are fused to the ware; therefore at 1000 C the marks will be well attached. Adding tiny pinch of the moist clay body can act as a carrier for the iron oxide slurry; the optimal ratio of clay body to iron oxide to water is determined by your testing and the way you apply the marks. keep it simple. LT
  18. @Bill Kielb @Min Bill, I won't argue your choice of design. The main point is to make sure that the incoming air is equal of the air being exhausted with the fumes. there are more one way to accomplish the requirement of having a safe environment in the kiln room. This particular room, as presented, has some missing information (aka constraints) that must be considered before making a sound recommendation. My comments are focused on making the assumptions visible especially to the person that will make the final decisions. I made a poor choice of the word "pumping" in the sentence: "If your window is the source of fresh air, you need to put the fan in the window pumping air in" The point is that fresh air must be forced into the room, which means from an area of higher pressure than that in the room. your explanation assumes the leakage rate is sufficient to remove the fumes created in the room and is sufficient to prevent the fumes exceeding the "an unstated" maximum concentration of fumes that will be allowed in the room; that maybe true, but if not, then the problem has not been solved. I have no preference of the designs available, but getting assumptions and constraints visible are important to make a sound decisions. LT
  19. that is the problem! To ventilate a room there must be an inlet source of fresh air and a separate outlet route for the exhausted air. These outlet exit must always be "downstream" of the of the environment of "fresh air" so that these two "airs" never mix, or the system will just be mixing/circulation device. This simple requirement is seldom mentioned in instructions for installation of venting equipment, and in online discussions. If your window is the source of fresh air, you need to put the fan in the window pumping air in and install a separate route for the exit air to leave the room such as the diagram in your initial post with a vent pipe through the wall into a chimney stack outside that terminates sufficiently high to keep the exhaust from being pumped back into the window by the fan. If you want to use the window fan to pump air out then you must find a different source (not the window) of clean air to come into the room. remember: for each volume of exhaust air you pump out must be replaced by fresh air. LT
  20. Yes. the college studio standard clear (and the base glaze for ~ four other glazes) cone 10 reduction glaze has 2-5% zinc and there is no evidence that the zinc evaporates. my memory says that some reduction crystalline glazes also have lots of zinc but i don't have the recipes. question: Has anyone set down and calculated zinc oxide decomposition to zinc vapor in a combustion kiln environment for the various oxygen levels at various kiln temperatures that the glaze mixture will see? All the data should be available in the CRC handbook or the NIST database. LT
  21. Yep; probably more of a "toothpaste" consistency paste applied first; followed by "lumpy butter milk" poured over it all. LT
  22. What I understand from your first post: the experiments are telling you that pieces dipped in water does NOT warp, non-dipped does warp. This does not sound like the clay based drying vs warping: therefore I would not force clay based techniques too much. From what you have posted, the mix does not contain any of the normal studio ceramic materials, especially clay. The following are some questions I would ask if I were a member of a problem solving discussion. in random order (probably will need some in depth thinking and lab testing): 0a. Is this a new reaction to the sintering testing in you company; 0b. are the compositions significantly different from previous tested materials? 0c. is the equipment the same as used previously without warping? What is different (other than the material composition) from previous testing that did not warp? 1. What happens to the test pieces if no water is used? 2. Why are the pieces dipped in water; could some other liquid be used? 3. Have you estimated the heat transfer rates from the kiln energy source to the test piece at various times in the kiln? Are these rates within what is normally used in making these test pieces? 4. How long is necessary to burn out the cellulose binder, and at what oxygen levels are needed to maintain the burn; do these estimated times make sense with the time in vs temperature profiles in the kiln? 5. What are the bonding between the particles dependent on the metal oxide layers, or are they depending on the binding of the metallic layers? 6. Does this "problem" occur on only on these specific recipes or does it also occur on the "other" recipes? 7. Are the orientation in the kiln the same as in the press; have you tried reversing the orientation to be different in the kiln from the pressing? 8. have you "bent" the pieces opposite of the warping to see if that allows the pellets to finish flat? additional thoughts: 9. Have you make a test piece from the press and examined the distances among the solid particles of the pellets? Uneven distances can lead to changes in shape of the pellet on sintering. One approach is to embed the pellet in a plastic block, and slice the block into thin sheets and examine under a magnifying device. same for the fired pellets. compare and contrast the two sets of data. 10. Warping is a result of uneven stresses and/or material strength; what would cause these conditions in the prepration and handling of the pellet and during time between the pellet is removed from the press and the time that the warping is discovered; what is actually happening taking minute by minute from press until warping is observed? 11. What is the friction between the pellet and the surface its support in the kiln; is this enough force to cause warping? 12. What is the material strength of the pellet at various times during the temperature profile from cold to cold; can you see the shape of the pellet at times during the firing; when does the warping become observable? (ik ben ook een ingenieur) LT
  23. As I remember from years ago listening to a college lecture on "glazing": The standard industrial manufacturing of cups, plates, etc. is to fire the green ware to maturity, inspect the pieces, throw away the cracked ones, and then apply a low temperature glaze to the "on spec" items followed with a low temperature firing. The details of getting the glaze slurry to "stick" to the mature ware is an industry manufacturing secret. In other words, such a process is doable. Finding a method for making your favorite low fire glaze "adhere" to the mature ware will be your challenge. LT
  24. I recall a "cup" piece by Ron Nagle that was glazed fired ~25 times. It depends on the firing temperature, the glazes, the clay body, and the heating & cooling rates, and sometimes the amount of cream in your neighbor's coffee two days after the firing. LT
  25. My initiation to ceramics I: the semester started with specific cone 04 Earthenware with a choice of white or red; fired to cone 3 in an oxidation gas kiln producing fully matured ware. at mid-semester the clay body was changed to a specific cone 10 stoneware with a choice of white, tan to dark to be fired a cone 10 in reduction kiln. Ceramics II was again cone 3 (earthenware) firing first half and cone 10 (stoneware) second half. (several years later all classes was cone 10 stoneware reduction). Some where along between earthenware to cone 10 was a semester or two it was all cone 5 (midware) fired in reduction. Today the studio is all stoneware at cone 10-ll reduction. I now use cone 10 clay bodies (because that is the way the kiln is fired) -- any kind -- for structural purposes of an object and use a clay of any cone -- earthenware to wild clay bodies -- as exterior coatings supported by any available high fire rated clay body. Some of my ware uses a cone 04 clay body as a glaze. This works for me. After determining the properties of the "earthenware" clay bodies fired at cone 10, I am comfortable with the way I am using the low fire clay bodies fired in the kiln I use and the way my ware is fired. I am making ceramic art even though the forms are often based on bowls and platters. The clay bodies are mature, the exterior surfaces are glazed with safe glazes. Firing low fire to a higher fired temperature is not normal, but then "ik ben niet normaal!". The cone 3 firing of earthenware was an easy way to make matured ware with bright simple studio glazes. If I were in the business of making drinking and eating ware with a bright strong color palette, cone 3 oxidation of earthenware clay bodies would be high on a choice list; but then I would not be making art, I would be making drinking and eating objects. I am making "interesting objects" with clay ceramics. Over the last five years and so, I have chosen to use any clay body easily available to me, and I make objects that I consider to be "interesting"; I use the term "container" for items that might be considered to be "mug" or some other use; the functionality decision is controlled by the user of the object not by the maker. Each batch of clay is different, and this reduces the boring tendency of making the same form over and over with the same appearance. The leftover low fire clay bodies from my early semesters was available, and I was given the latitude to experiment and to learn something. Improvise, Adapt, Overcome is the driving force for what I make and how I do it. Min, I suggest you take the available low fire commercial clay bodies and find the firing cone that will vitrify to the point that it won't leak without glaze. use that clay body to make your ware, take low fire glazes and fire them to that temperature. Start with firing low fire glazes at the mature temperature for the low fire clay. LT
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.