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  2. I am a beginner in the field of glazing , i want to make some tiles and i heard about a technique called cuerda seca mostly used on tiles work. i searched alot for the recipe or formula for the material used in this technique to be applied by silk screen but can’t get what am looking for, just found one product called artistic line resist but unfortunately it couldn’t be delivered to my country. so please if anyone could help me with that i will be so thankful, all i know about this material that it contains a bit of wax
  3. For wood fire box areas you NEED hard brick . Most folks who build wood fired kilns use 100% hard brick due to the fact that they last. In the areas aways from the wood you could use IFB like K26 or K28. Youi will find in heavy use or higher heat areas K23 will spall over time. You can use fiber to back up any of these materials for insulation. If the wood heat source is distant fiber can work as well. In all the years here (in this forum and elsewhere ) I have seen folks try lots of things that are not standard either to save money or they have a better idea.The outcomes are predictable. Heck I'm one of them-I build a salt kiln with hard brick ,soft brick and fiber roof. I learned where the limits are. I did not try this to save money (except for fuel costs) I did learn a bunch and after building that kiln and firing it 10 times and thats after building 10 kilns so thats saying something. Now the other factor is how much one will be using the kilns they build-once a year -every week or something more or less. You can dig a pit and fire clay but theres not a huge market for sale items from that pit. Whats the intended long term plan for firing?? Many factors to consider. If you have time and are resourcefull used hard brick can be had cheap.I just saw a few pallets on facebook marketplace last month near me for 1.50$-to 2$ a brick depending on how many you bought .
  4. Educational Post Firing Schedule Variables There are several key issues that effect the final firing schedule selected. 1. Functional or Non-functional use. 2. Wall thickness: thrown or hand built up to 3/8". Structural starting at 1/2" up. Sculptural with varying thickness/ parts. 3. High iron/ carbon bodies vs. white body. 4. Single fire vs. bisq. For the bulk of most firings; functional or non-functional and single fire vs. bisq fire comprise most firings. The additional variable is how thick are these pieces? Several universities across the world have done studies using X-ray defraction to measure heat work in gradient kilns. The general consensus being that it can take up to 30 minutes for the atmospheric temperature to reach the core of the clay body in the 3/8 to 1/2" thick range. In order for clay to fully mature, this variable has to be included in the firing schedule for functional wares. Absorption rates increase, COE values can change and firing defects such as pin holing, blistering, and shivering can be attributed to firing schedules. Sodium (Nep Sy) is the flux of choice in the USA and Canada; and is commonly used in other parts of the world. It is a cheap body flux but it does create issues. Sodium begins to melt at 2044F, and potassium at 2012F, as the clay is converting from spinel to mullite at 2050F. In application; at the same time sodium begins to off gas vigorously, the porosity of the clay is beginning to close up. Extending the time climbing to peak temperature allows the feldspars to completely off gas; thereby resolving pin hole issues while maturing the clay. Selecting a preset ramp speed or programming your own depends upon the clay body, piece size, weight, and foot ring contact. In addition, starting at single fire or from bisq also decides ramp speed. Pieces with wall thickness above 3/8", heavy pieces above 7lbs, or pieces with large shelf contact such as platters need slower ramp speeds to allow for even heat distribution. Slower speeds during the quartz inversion range is also advisable for large format pieces Quartz inversion occurs at 573C (1064F) when quartz changes from alpha to beta phase. Silica (quartz) actually expands at this temperature: part of an exothermic reaction. Just prior to this phase change and to just above this temperature: molecular moisture is being driven out of the body resulting in overall shrinkage. These two processes are occurring relatively at the same time: overall shrinkage from the loss of molecular moisture, while silica is expanding during inversion. If pieces are heavy enough, have weight, or have large shelf contact such as platters: cracking can occur. The remedy for this issue is programming a 100F per hour climb from 1000 to 1100F before resuming higher ramp speeds. You can actually increase firing speed to 180 to 270F an hour if firing porcelain or white stoneware. The overall size and weight of the piece may still justify a slow ramp cycle once you pass the inversion temperature range. Wadding, sand, or alumina may be placed under large/heavy pieces to facilitate movement during the firing cycle. Dark and red bodied stoneware produce buff, terra cotta, and brown bodies that potters love. While they produce warm toasty colors, those colors come from iron disulfide. (Pyrite) in addition, lignite coal particles are common contaminants. Both sources of sulfides require special firing cycles to prevent blistering, bloating, and carbon coring. Inorganic carbons burn off from 1250 to 1750F, and require heavy oxidation during this temperature range. Rather single firing or bisq firing: programming a slow cycle of 108F an hour (slow speed) from 1250 to 1750f an hour while oxidizing the kiln is required. If single firing; you are simply programming a bisq fire, while incorporating the final ramps to peak temperature. If firing large, heavy, or large foot ring pieces: then adding a quartz inversion cycle is required. If firing dark or red bodied stoneware; then programming a slow ramp (108F) from 1250 to 1750F while oxidizing the kiln is required to avoid blistering, bloating, and coring. Once you reach 1800F in a single fire, then you can increase ramp speed to 180 to 270F until you hit 2050F. At this temp, speed is then reduced to 108 to 125F an hour to allow escaping spars to escape before the clay body vitrifies. University studies from around the world all report an endothermic reaction at 2050F as observed by X-ray defraction. It is a key reaction temperature in the firing cycle; when the porosity of the body begins to close rapidly. Most clay bodies in the USA and Canada use Nep Sy (sodium) as a body flux. At 2044F, sodium becomes reactive and off gasses vigorously; which appears as pin holes in the glaze. Rather single firing or starting from bisq; slow ramping from 2050F to peak hold allows the extra time for off gassing spars to dissipate. Recommended ramp cycle from 2050 to 2232F is 108-125F an hour. A commonly used peak temperature is 2190F with an extended hold: use the recommended ramp cycle for this program firing. This slow ramp cycle towards peak range also has the added benefit of extending element life. Tom
  5. Do you see the specks on the unglazed foot ring, or just the glazed part?
  6. Yesterday
  7. Right now 40 jars sitting in the shop waiting for honey/spoon lids, 26 in the kiln, Mug throwing next week 75 for the order, probably get them thrown on Tues & Thursday. Recycling thawed out clay is rougher this year, but doable. Now use a heavy wiggle wire to cut bread slabs, spray and slam. Used to put finger holes in the slab, this is quicker and easier. Wiggle grooves hold water well. best, Pres
  8. I've been using some leftover scraps from "Construction Plastic". It's what contractors and such put up, to protect against dust getting out of the work area, to catch paint drips, etc. It's thicker stuff, and keeps the moisture in quite well. It's been so rainy here lately, that my basement stays pretty damp itself. If I just poured some plaster on the floor, it would be one big damp box.
  9. Rust particles (iron) can be all over many surfaces. Check your clay cutting wires-jar lids -vacumme the kiln again as well as the bands around the lid and the lid. It would also help by doing your elemnts with a soft brush on the vacume as well. Seive the glaze-Just think like a small ruct particle . I would also test a pice of clay unglazed to see if the specks are in that body as well in a fire. Since you are using a commercial glaze you have ZERO control other than sieving it. The finer the screen the better for those paricles look really small. looks like rust to me.
  10. are you adding any water to the glaze? Check to see if the iron (or other trace elements) content has increased since you last had pure white glaze. Our water system is having its routine "flushing" for cleaning the distribution piping from corrosion sediments. LT
  11. If putting the glaze through an 80 mesh sieve doesn't solve the problem I would contact Laguna. Let them know everything you've done to solve the issue, glaze and clay batch numbers and your results.
  12. 203 boxes of miscellaneous glazes 24 - 4 oz jars per box need gone quickly. FREE, FREE, FREE Barrie, Ontario
  13. Sneaky? I thought is was rather overt myself. Besides, it is viewership round up month. premium porcelain is 50% grolleg, 25% silica, and 25% Nep Sy. + 2% macaloid (Bentone ma) this is the fix it mix. If you do not have grolleg, then use EPK. EPK will diminish translucency a bit- your call. how much fix it mix you add is directly proportional to the amount of water you use throwing, which equates to how much fines you lose. So you have to make that judgment. For a gallon full of dried reclaim 1/8-1/4 cup of fix it mix will work. Most of the members post pictures of their work in the gallery. I am limited where I can post mine.
  14. OK I have been cleaning out recieptrs long buried -heres is an up date on Old Westwood ceramics receipts before Laguna bought them out price of large cones in 9/1977-2.15 cents per box 1975 1# cobalt carb $7.35 9/1977-back when 100# bags where the norm- #100s of Kingman $6.00 #100 Kentucky ball $6.15 #10 red iron ox. 5.60 Those where the days my friends update bought my second Brent wheel in 4/30/1982 a CXC from Kickwheel Pottery Supply cost delivered $631.70 with splash pan wheel was $570-splash pan $25 shipping $35.70 One last note is I saw an old wholesale tag from 1980 and my ceral bowls where $4 each as well as the mugs.so its all relative .
  15. So much to digest there, THANK YOU. Honestly this kiln has no chill, getting a smooth sane ramp to 1500 is extremely difficult. At least for me at this point in my evolution. Also that digital control panel is mouth watering, and I'm 3 minutes into the video and already my core understanding of reduction is being redefined. Also note that when I do the electric -> reduction chamber route, I take the pieces out at 1750'ish, max. Higher than that and the nitrates seem to burn off. I'll absolutely get some more experiments put together this weekend and ping back with results.
  16. Bought the first one for the HS in mid 80's, and they weren't what I would call cheap back then. . . .the years and popularity has not really increased the price more than inflation. IMHO best, Pres
  17. oh, for heaven's sake! this reads like a sneaky way to advertise your latest contribution to Ceramics Monthly magazine. i am embarrassed. (and that is hard to do!)
  18. bet the receipt for your giffin grip showed a very small amount of money for such a great tool. today they cost as much as my first kiln did, with shelves and posts.
  19. Dearest Oldlady: coleman porcelain actually originated from experimental bodies used at Alfred. This article covers clay recycling, and Coleman in perticular. Premium cone 10 porcelain is 50% grolleg porcelain, 25% silica, 25% Nep Sy, and 2% Macaloid. (BentoneMA) instructions are in the article https://ceramicartsnetwork.org/ceramics-monthly/ceramic-supplies/ceramic-raw-materials/techno-file-clay-restoration/
  20. I wondered if it was rust too. But all the glaze jars are plastic and my brushes don't appear to be rusted on the bands. As mentioned in another comment, I think I need to try sieving the glaze. Surely that will help. Thank you, everyone, for taking the time to reply. I really appreciate it!
  21. we have 203 boxes of 4 ounce jars of these glazes I would give free to a good home. you come and take away. I am in Barrie Ontario Canada.
  22. A recent thread on culture made me think about periods of art history. Being an arm chair historian, I often go through the history of potters before us: Adelaide Robineau's Scarab Vase comes to mind. Historians put art (including pottery) into periods: Medievel, Renaissance, Baroque, and Neo-Classical for instance. (Google "periods in art history"- you will find them) Each period in recent history lasted 100-200 years: the current period began in 1800. So if periods last 200 years, that would mean beginning in 2000, a new period should have begun.....but it has not! Qotw : what name would you ascribe to the current period of art history that began in 2000?
  23. I understand the view, of those opposed to them, as they see it as a crutch, to a process that potters should know. But it is a quick way to center, especially in the bulk, that you are dealing with Mark. It is also a good way to recenter for decorating. I just used mine to day, to recenter a leatherhard piece, right side up, to apply even coats of underglaze. Tap centering that form, right side up, would have been quite difficult. Plus, the feet hold the ware in place, without leaving clay dust on the outside areas, I already underglazed. Also, in my classroom, the Giffen Grip is invaluable. I barely have time to teach the kids to use the wheel to throw the form, so I definitely do not have time to teach them tap centering. So I can still teach trimming, without that extra step and frustration. I still talk about tap centering, and show it to them, I just don't expect them to do it. Regardless, tap centering isn't going anywhere. The Giffen Grip does not work well for altered forms, that aren't symmetrical, and of course, not everyone wants to spend over a hundred bucks, for a Giffen Grip.
  24. Cone 10 porcelain does not have to be fired in reduction, but 99% of people who fire in a gas kiln do so in reduction.
  25. I was going thru an old filing cabinet and found my orginal receipts for my 1st Giffen grip and a letter from Brian the owner thanksing me for buying it. Dated 1984. I know these are still controversial but for me they are (I own 3 of them now as well as the larger one) just another tool in the tool box the past 35 years
  26. are the lids on the glaze containers metal; are you using any metallic containers, tools, brushes, etc. in the glazing steps?
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