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About AnnaM

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  • Birthday October 17

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    Art deco, retro 50's & 60's pottery
  1. PS And you can increase plasticity by using plasticisers to make a throwing body.
  2. Cavy, you can make clay bodies yourself to vitrify at any temperature you like really (within reason), You can't buy low fire vitrifying commercially made bodies unless its somoething like egyptian paste. They often lack plasticity which doesn't suit most people who throw or handbuild. When I started researching these bodies I started a couple of threads on here (it was about a year and a half ago from memory) and I posted some recipes that I was trying, as did some others. The first thread was called Cone 04 porcelain I think. You can also use recycled glass cullet with is much cheaper than frit. If you have access to university data bases you can find lots of information in the ceramic engineering/industrial journals or dental ceramic research. They have a far greater knowledge of the chemistry and behaviour of clay bodies (probably as they appraoch them from a completely different paradigm) than most of us ceramic artists! They are also more experimental as industrial requirements for ceramics are so different to the requirements of potters and artists (ie ceramics in various technologies). You just need to push and test. The recipes on the other thread are a good place to start. Throughout history there have been lots of different iterations of what makes a particular clay body (despite what comtemporary porcelain purists will say) and many large scale crockery producers use lower firing bodies as it speeds up their production, but they have developed their own bodies that are hard enough and durable enough for daily ware. Its a worthy pursuit to try, even if for nothing other than to understand your materials and their limits better
  3. AnnaM

    groggy recipe

    Hi Babs! yes I will post some more when I have a finished piece! Its all research tests and experiments for school at the moment! I'm well, I hope you're good x Anna
  4. AnnaM

    groggy recipe

    Hi Cavy, Yes thats mine, its evolved quite a lot since then! Anna Mallyon
  5. I screen print my own decals using decal paper, onglaze powder mixed with decal medium and a cover coat liquid which burns off in the decal firing. You just have to remember to get the water soluble medium, and clean your screen immediately after each pass as the medium dries quite quickly and will ruin your screen.
  6. That's strange that wouldn't sell it to you! I hope it's not hard to get, I've been considering trying to find a supplier that would ship it to me here in Australia. Annoyingly no one sells veegum or macaloid here. The whitest firing plastic clay we have (that I can get in Melbourne at least) is clay ceram, a different name for Tennessee ball clay, I believe.
  7. I think I remember reading once that vee gum is hectorite with some other gum additive and is more plastic than bentonite alone. Have you mixed a batch yet?
  8. Neil - I think the beads are between 53 & 75 microns, its very fine powder. John, it's not from an MSDS sheet, it's just their table that has the typical composition, that was all they had. I'm not necessarily going for translucency at low temperature, but I do want a strong and vitreous body, and I would like it to be as white/light as possible. My kiln doesn't quite get to 1100C (and thats a struggle for it, I can't really push it past cone 03) which is why I got interested in this project initially. Unfortunately, none of the commercial earthenware clays available to us here in Melbourne are vitreous and they are fairly weak (they chip really easily) so I normally add frit to my earthenware bodies to lower the MP and produce a much stronger, vitreous body. The only problem with that is that the frits here are quite expensive, which is why I was interested in developing a recipe with the glass powder. There are a few research papers where people have trialled cullet with good results (in industry rather than for artistic purposes), and I figure once I know what sorts of issues I'm going to encounter if the composition varies (eg, if the alumina decreases or increases, if the soda decreases or increases, etc - how will I tell, what will give me an idea of what's changed and I think thats only going to come from understanding the chemistry really well), then I can adjust the recipe. This is why I asked for title of good textbooks to chase up, so I can have an understanding of what the various components will do in a clay body, so if something goes wrong I have at least an idea where to start to adjust. As it stands now the body is good, except for the fact that it seems to be absorbing the glaze. The translucency is the added bonus. I'm aware that for those who have access to kilns that can reach stoneware temps it must seem like such a waste of time and effort, but I've had a few emails from people in the same situation as me that are watching with keen interest. And if I CAN work this out, in the long run it will mean that I'll save money on firing, plus I will have the added benefit of the expanded colour palette. It may prove to be fruitless eventually, but for now I keep making steps forward so I'll continue on. It would just be easier if there were others that had tried this and succeeded on a large scale that I could get guidance from, and without a ceramics chemistry training I feel like I'm walking forwards blindfolded. If I can succeed, I think the benefits will be very well worth the effort.
  9. Could be Nancy! Babs, you are a legend thankyou! John, its used in glass manufacture, containers, electrical glass, construction and automotive glass apparently, stuff like that. I think she said its the stuff they mixed with paint for road marking to make it reflective as well. The powder is actually tiny glass beads, it's typical soda-lime glass. When I spoke to her she said even though the proportions given are a range, that the actual proportions generally don't change - but she couldn't give me a specific composition for the batch I have. I'm going to see if I can get one done I think.
  10. I'm not offended, but I don't understand the question Babs! What do you mean embezzlement? I wish I could just use frits, but in Australia they are really expensive, between $54 & $60 per 5kg I had them send the breakdown of the cullet (which is below in case anyone is interested), is there any point in comparing recipes in insight and then adding whats missing with the absence of the particular frits? Chemical Approx. Limits mol% SiO2 62 – 84% Na2O 6 – 16% CaO 5 – 14% MgO 0 – 6% Al2O3 0 – 2% K2O 0 – 2% LiO2 0 – 2% FeO/Fe2O3 0 – 0.6%
  11. Yes, the kiln has elements in three walls but not the door. No, all the other cups (that turned out perfectly with the same glaze) are a commercial earthenware clay fritted with Ferro 4131 though. (I do this because none of the commercial earthenware clays in Melbourne are capable of holding water unglazed and they are extremely weak, too weak and seepy for functional ware). So different body for those. There is no matt 'side' as such, there is uneven mattness & gloss around the whole vessels (which is why I was wondering if it could have soaked in) The problem is confined to those vessels. Also these two problematic vessels had two more coats of glaze on them (4 coats in total) than the ones that turned out perfect which had two. I have made this recipe using Ferro 4110 (in USA 3110 I think?) and didn't have the same problem (except where a pot had underglaze on it, but the naked area loved this same glaze). I'm wondering if adding in the extra ingredients that would have been introduced by the frit would have any effect? I think the 4110 is a high boron frit? The cullet obviously misses the boron and whatever else is in the frit. From previous threads though, my understanding is that adding soluble boron into a clay body might not be feasible, is that right?
  12. Also the distribution of glossiness isn't confined to one side only, eg the sides that were facing the elements, its some top here, some bottom there. It looks like there were areas that didn't have glaze on them at all (despite having several thick applications). Can glaze soak in to bisqueware?
  13. They were on the top shelf at the back (my electric kiln is tiny - 33 x 33x 33cm - only 1cf or so, front loading) so they were close to the wall. It was 200C per hour to 850C then on full, but it takes my little kiln a long time for that last couple of hundred, it was four hours for the C04's to go over all the way.
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