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PeterH

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  1. Would you feel happier experimenting with a cup full first. You can then put it back into the bucket with an idea how much more deflocculant you will need for the whole bucket.
  2. >Peter - how would a volumetric line blend help me in this case? I haven't done one before! It's an easy way of making a batch of glazes of different compositions. In your case you might make two glazes with 25% more and 25% less orange, then do something like this: PS ... assuming of course that the sweet spot for your glaze is in the range -25% to +25% as you suggested
  3. >If I increase the black and orange by 25%, or even decrease it by 25% I may be able to recreate the "fluke" glaze. Maybe it's time for a volumetric line blend? PS You could probably increase the reproducibility by measuring the orange as two lots of 1.0 & 0.7 on the gram scales.
  4. Mildly depressing information about polyvinyl alcohol Polyvinyl Alcohol: Properties, Uses, and Application https://www.toppr.com/bytes/polyvinyl-alcohol/ There are two ways in which the 4% aqueous solution of Polyvinyl alcohol (PVA) may be created. The first uses a conventional heating method, the second uses the microwave heating method. The latter is easier to conduct and is less time-consuming. Once the 4% PVA solution is made, it can last between 6 and 8 weeks. Generally, it is advisable to refrigerate this solution, which supports the growth of bacteria. When making the Polyvinyl alcohol solution, it is recommended to use tap water, as bacteria grows faster in PVA containing distilled water.
  5. Min - see pm I've failed to find the patent mentioned earlier, but this one suggests that a wide range of binders can be used: Ceramic composite article prodn. - by bonding parts with binder of ceramic filler in aq. polymer soln. https://patents.google.com/patent/DE3938933A1/en?oq=+Bibliographic+data:+DE3938933+(A1)+―+1990-05-31++++++|+++++In+my+patents+list+++++|+++++Report+data+error+++++|+++++Print+++Ceramic+composite+article+prodn.+-+by+bonding+parts+with+binder+of+ceramic+filler+ (A) In the prodn. of a ceramic composite article by bonding two articles of the same ceramic material using a binder and then sintering, the ceramic articles have the same thermal shrinkage at room temp. to the sintering temp. and the binder consists of the same ceramic material as filler in an aq. soln. of a water-soluble polymer. (B) A binder, for bonding ceramic articles, consistse of a ceramic filler in an aq. soln. of a water-soluble polymer. Pref. the polymer is one or more of methylcellulose, carboxy carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, polyacrylic acid, polyacrylamide and polethylene oxide. USE/ADVANTAGE - The binder is esp. useful for binding calcium phosphate type ceramics to produce a bio-material. The process and binders low cost and avoid leaching out of noxious substances during use of the article.
  6. The idea seems to have some relationship to ceramic tape technology. The Emer's glue DIY version is described in the frequently mentioned: Tape Casting - Alfred Grinding Room https://static1.squarespace.com/static/527ac372e4b0d4e47bb0e554/t/527fd23fe4b0f7fd724aba83/1384108607291/tape+casting.pdf ... which contains the advice Careful consideration must be given to the firing schedule in order to allow the binder and plasticizer will burn out completely. A rate of 50 F up to 500 F is generally acceptable for this.
  7. You may be interested in an earlier thread on this topic, and my summary of an old paper on the topic. PS Ian Currie's book is now at https://s3-us-west-2.amazonaws.com/wiki-glazy-org/documents/IanCurrieStonewareGlazes.pdf Reduced copper glazes are discussed on page numbers 189-193 (but local reduction is only mentioned in passing)
  8. CMC powder is available at https://www.bathpotters.co.uk/cmc-finnfix-organic-polymer/p3690 This may be of interest V gum T, but 1Kg https://www.scarva.com/en/Scarva-Raw-Materials-Vee-Gum-T/m-6517.aspx
  9. FYI, as somebody has mentioned hydraulic presses ... These tile-makers considered making the DIY press described in Handmade Tiles by Frank Giorgini, but instead added press plates to a cheap commercial press. https://createniks.wordpress.com/2010/04/24/hydraulic-tile-press/ ... less powerful/cheaper presses are available! Two addenda on their first tile mould. https://createniks.wordpress.com/2010/05/13/first-mold-for-the-tile-press/ https://createniks.wordpress.com/2010/05/20/our-tile-press-rocks/
  10. Any chance of a photo of your "canisters"? Some shapes are easy to cast, some harder.
  11. You might be interested in this item from over at the Ceramic Arts Network. Flat Tiles The Easy Way https://ceramicartsnetwork.org/daily/pottery-making-techniques/making-ceramic-tile/flat-tiles-the-easy-way/ It recommends 8-12 hrs on drywall and then a wire shelf.
  12. Hamer&Hamer mirror Min's concerns on wreathing and deflocculation. https://tinyurl.com/yyx5z39l However they add that "swirling the remaining slip around the mould before draining may help to overcome the problem". PS for what it's worth Valentine's recommend an identical slip recipe for use with their Fine Bone China Granulate. https://www.valentineclays.co.uk/product/fine-bone-china-granulate When making casting slip from their plastic clays they recommend using both sodium silicate and soda ash for all except the bone chinas. Irritatingly they also give suggested control parameters for all but the bone china. https://www.valentineclays.co.uk/sites/default/files/downloads/Technical Analysis Chart - Industrial Products.pdf
  13. You are absolutely right, I very much doubt that doped crystals could reconstitute themselves, even if the firing conditions were ideal for recrystallization of the host crystal itself. Regards, Peter The "why they mixed it with alcohol rather than water" point I'm less clear on. I mentioned it in case anybody else could spot it's significance (if any). As you bring the point up I'll elaborate on my position. I didn't believe that strontium aluminate was water soluble, but I couldn't find a handy reference giving an actual number. I did find several data-sheets claiming that it was insoluble in water -- but also one that suggested that is was soluble in water. However use of water-based media such as acrylic seems to be recommended for the pigments. So my current belief is that water solubility just isn't an issue. I suspect that the chemists used alcohol-based techniques in the preparation of the glaze because (in their line of work): - It's what they are used to doing (accuracy and reproducibility are important to them, so tried-and-tested is rightly valued) - You can evaporate alcohol easily, especially with a mild vacuum (time is money) - The cost, H&S and waste-disposal issues are insignificant in a lab context But that's probably because it's the only vaguely plausible explanation I can come up with.
  14. This paper discusses a low-fire glaze for strontium aluminate based pigments. https://tinyurl.com/yyvafwbl Bottom line is 80% borax, 10% potash feldspar & 10% kaolin. Consistent with my suspicion that high-alkali glazes might be best avoided as they might attack phosphor grains. Presumably needs reformulation ... non-soluble ... frit based.
  15. Just wondering, if he is a lapsed member a p.m. may not get his attention. Is the any way for [a moderator?] to send an email?
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