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    • Jennifer Harnetty

      Moderators needed!   12/08/2017

      Ceramic Arts Network is looking for two new forum moderators for the Clay and Glaze Chemistry and Equipment Use and Repair sections of the Ceramic Arts Network Community Forum. We are looking for somebody who is an active participant (i.e. somebody who participates on a daily basis, or near daily) on the forum. Moderators must be willing to monitor the forum on a daily basis to remove spam, make sure members are adhering to the Forum Terms of Use, and make sure posts are in the appropriate categories. In addition to moderating their primary sections, Moderators must work as a team with other moderators to monitor the areas of the forum that do not have dedicated moderators (Educational Approaches and Resources, Aesthetic Approaches and Philosophy, etc.). Moderators must have a solid understanding of the area of the forum they are going to moderate (i.e. the Clay and Glaze Chemistry moderator must be somebody who mixes, tests, and has a decent understanding of materials). Moderators must be diplomatic communicators, be receptive to others’ ideas, and be able to see things from multiple perspectives. This is a volunteer position that comes with an honorary annual ICAN Gold membership. If you are interested, please send an email outlining your experience and qualifications to jharnetty@ceramics.org.

earthfan

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Everything posted by earthfan

  1. How To Reveal Lace Texture

    I notice that you have pressed lace into the ornaments. What looks even better is to press the lace into a slab of clay about 8mm thick, wait for it to firm up a bit, then remove the lace. Dry the clay slab and fire it to bisque. Use that as your mold for lace texture. It is easy to do on a small scale and your pieces will look as if they have real lace stuck on them.
  2. Spodumene

    The spodumene supplied by the Greenbushes mine is a fine sand that is 88% spodumene and 12%silica. I fired a little bowl of it to about cone 7 and it converted to beta spodumene, puffed up and turned into a fine pink powder. It did not melt at that heat and didn't even fuse to the bowl it was in. Spodumene has one molecule of lithium oxide to one molecule of alumina to 4 of silica, so it is like feldspar, but with a lower proportion of silica. Spodumene has a negative co-efficient of linear expansion. It doesn't shrink when fired, it gets bigger. Lithium carbonate is Li2CO3 and is slightly soluble. That is what you need to spray on the raw clay to get a sheen. "Ceramics Monthly" of February 2015 has an article on spodumene.
  3. Don't neglect the traditional hand-building methods. It takes a lot of practise to make a large pot on the wheel, but by using coils, a complete beginner can make a large pot at her first attempt. Slab building also has much potential because you can add texture in ways that are impossible on a wheel. A good tool is a long pastry rolling pin and sets of two wooden slats the desired thickness of the slab you want to make. Even better is a potters' harp, but I don't know where you get them nowadays. Always make everything bigger than you want them to be because of the 12% to 14% shrinkage. The limitation with wheel thrown pots is that they always come out round. They can be coaxed into ovals and squares, but there is never the shape variation that is available when using coils. I don't know what sort of wheel you have. Mine is a Venco and it can be easily converted to a work table just by placing a piece of chipboard over the top. Discarded cupboard doors are a good size. Again, fibro cement is the ideal work surface for slab and coil work, so long as it is dampened. Place it over a sheet of plastic to protect whatever you sit it on.
  4. Duncan Gold Luster Question

    A different issue: I want to apply lustre to stoneware. Would it fire onto a glaze that was already high fired, or would it require a layer of glaze that would fuse at a lower temperature?
  5. If you are in Australia, you will have access to fibre cement, which is the best stuff for wedging tables and bats. Fibre cement has a smooth side and a textured side, and, when dry, it sucks water out of slip very quickly. When using it as a work surface it will be necessary to keep it damp, or it will dry out your clay too soon. (Make sure that it isn't asbestos cement.) It is fairly cheap at Bunnings and local hardware shops. You can cut straight lines with the scoring tool they sell for the purpose, but you will want round bats when you start to throw wider things. An angle grinder with a masonry disc will allow you to cut out discs of fibre cement. If possible, get your wheelhead fitted with two removeable pins.
  6. Making A Kiln Lid

    Does the lid have to be brick? My homemade gas kiln is top loading. The lid is a frame of stainless steel with a couple of bits of angle aluminium across the top from which homemade ceramic buttons on shanks of kanthal element wire, suspend 5 inches of ceramic fibre. I get into the kiln by lifting each side onto a hook and swing it out of the way.
  7. Is It Ruined?

    I like the dirty dish story too. Reminds me of an acquaintance who fed a roast dinner to 35 people one Christimas, She roasted a leg of pork, a leg of lamb and a turkey, together with trays of potatoes, carrots and pumpkin in her front-loading kiln.
  8. Throwing Thickness

    When you are considering how heavy a pot can be, you need to take into account the weight of the pot PLUS the weight of the intended contents. Also, whether the user will be happy to use two hands, or will want to have one hand free. A light pot is more practical, so long as the rim is thicker and smoothly rounded.
  9. Crazing

    "went to a big pottery show at the weekend and was shock to see pots at £450.00 with crazing on them tut tut" If people pay 450 pounds for a pot, they are not going to use it, so it won't matter if it is crazed. Many years ago, I went to an exhibition of work by Greg Daly, who writes books on glazing. The work was beautiful big platters with up to 4 different stoneware glazes layered in various ways. I was horrified to see that the glazes were about a centimetre thick and thoroughly crazed. I attended his seminar and, of course, he wasn't giving away his glaze recipes. Which was OK by me because I didn't want them. My latest idea is to raw glaze to stoneware temperature, and decorate at a lower temperature. Still only two firings. Haven't done it yet.
  10. Potters And Pets

    My last cat died at the age of twenty. Now I don't have to feed anyone, ever again, if I don't want to. But women seem to have the instinct to feed something. I don't want a pet because I want to travel. So I feed the bandicoots that live in my yard. And the birds, too, of course. If I still had a cat, I would photograph her playing, and decorate my mugs with cat silhouettes, because cats form attractive shapes. But I have no cat. What I do have, is a visiting kangaroo. I have static photos of him grazing and a couple of him jumping away from me. He is jumping because I am chasing him with my camera. He makes interesting shapes too, but I am afraid that, except for the jumping pose, the silhouettes won't be recognizeable as kangaroos. I would love a sprig of a kangaroo.
  11. Uneven Bottoms! Help Me Out

    Have a look at the containers for sale in the shops, and the containers in which yoghurt, dips and icecream are sold. Every single one has a foot ring of some kind. The bottom of a vessel MUST be concave. I have a plastic cup that has a foot ring of tiny half domes, which I consider to be ideal for dishwashers, because they don't collect grotty water. Vitrified stoneware has a tendency to slump a little when there is a wide span of bottom unsupported between a foot ring. I give plates a double foot ring, one on the outside and another small one closer to the centre point.
  12. Plate Stand For Glazeing

    Small homemade shelves in different sizes allow shallow things like plates to be fired as a stack rather than spread out over a whole shelf. You cut a triangular shape out of thickish chipboard and place it on a smooth surface and pound the mixture into it. The shelf mixture is 50% fireclay and 50% stoneware grog in a mixture of sizes from dust to little chunks. Fire a cone higher than you are going to use it. Perhaps find someone who fires to cone 9 or 10. The more they are fired the better they are, because mullite develops with every firing.
  13. Cracking W/split Rims

    Instead of stamping, could you get the same effect with a sprig?
  14. Staining with oxide is easier on bisque. You can clean off the excess without damaging the texture. Use an eyedropper, rather than a brush, to flow a very dilute mixture of water and oxide into the grooves. On stoneware, straight iron oxide fuses to the clay at cone 8 without any flux.
  15. Wax Resist

    Better than sponge or brush is the hair dye dispenser bottle, the kind with a lid. Water based wax resist, stained with food colouring, can be stored in it. Have the piece centred on the wheel or banding wheel. Shake up the bottle and tap its bottom a couple of times so that you don't get a big glob of wax coming out when you start to wax trail. With the wheel turning, flow a thin line of wax on the highest point of the foot ring. The tip of a brush can be used to spread the wax a little. So only the very tip of the brush gets wax on it and it is easy to clean.
  16. Diy Sieve

    I made a sieve from brass mesh and a plastic bowl with flared sides. Because the sides are flared, it sits into the top of any bucket. The area of sieve is larger than that of the Talisman. I would love another. but our pottery suppliers no longer stock the squares of 100# stainless mesh, I sharpened up one of my turning tools to a point. Using the widest sliders, I put the bowl in my Giffen grip and peeled a groove where the side of the bowl curved around to the base. When it got thin enough, it was easy to cut with an exacto knife. I used a soldering iron to join the mesh to the plastic. Just spots on opposite sides at first, then all the way around. The soldering iron softens the plastic and the wires of the mesh get embedded in it. This needs to be done outdoors, because the fumes are noxious.
  17. Throwing Thickness

    I like a thin walled cup and so do my customers. I don't think that it is possible to throw a cup on a wheel and have it come out too thin, except on the rim. It is easy to make the rim too thin. Slip casting allows thinness, but cups that are too thin let the liquid cool down too quickly. Hand made cups act as a bit of a heat sink, but only if they are warmed with boiling water before filling.
  18. Might I suggest a small offering to the kiln gods: flowers, fruit, joss sticks. To Old Lady: the oz use of abbreviations is extensive. I blame the print media. By shortening the words, they can use larger lettering. eg pollies=politicians; ambos=ambulance drivers (paramedics); garbos=garbage collectors; firies=firefighters; rellos or rellies=relatives; vollies=volunteers. I have heard reference to volly firies, that is volunteer firefighters.
  19. Meat Grinder As Pugmill?

    I don't have any canvas bags, but the legs of old jeans work just fine as long as they don't have holes in them. A friend has a jeans leg attached with some kind of clamp to the outlet of her wheel splash pan . The sewn up hem end sits in a bucket. All the throwing slip and turnings go into the jeans leg. When the jeans leg is full, she ties up the open end and lets it stiffen. The cut and slam method of wedging doesn't require very much strength. You don't have to lift the whole lump of clay, only half at a time.
  20. Meat Grinder As Pugmill?

    The cut and slam wedging method has the advantage of exposing any grotty bits that have somehow got into the clay. My own hair, for instance. Pug machines or kneading, spiral or otherwise, don't help you locate and remove unwanted small bits.
  21. Meat Grinder As Pugmill?

    I have access to two Venco de-airing pug machines. Our pottery club has one for white clay and one for dark. But to take my clay with me when I am on duty, and use the pug machines, is more trouble than it is worth. Two years ago, I pugged several bags of clay that I had wetted down and it wasn't any fun at all. I had to put the clay through twice to get the rid of the two colour spiral that remained in the clay after only one pass. I have not used the machine since. I have gotten very efficient at cut and bash wedging and call it 'exercise'.
  22. Crazing

    Crazing is the bane of my life, even though I work in stoneware. The thing with earthenware is that the glaze will eventually craze, even though it doesn't do it in the kiln. With use, the absorbent body takes in moisture from the air and dishwater, which makes it expand slightly, which stretches the glaze so that it splits.
  23. Clay Storage Environment

    The ideal storage is in an old (dead) fridge or freezer, kept somewhere in the shade. In summer we stop the clay from drying out by draping wet towels over the bags of clay in the fridge. Pieces of plaster soaked in water would serve the same purpose. Plastic bins split.
  24. In Australia we call this glaze 'tomato red' even though it is unlike the red of a tomato. I read somewhere that the red colour is iron phosphate made by the combination of phosphorus from the bone ash and iron in the iron oxide. Does anyone know?
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