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About andros

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  • Birthday 12/09/1984

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    Trieste, Italy
  1. learning to use underglaze

    If, as I belive, CMC is the acronym of Carboxymethyl cellulose, then it is available in any... shop specialized in supplies for pastry! I have already used it for some glazes, but the first time I bought it to make sugar paste icing for a cake... If I have understood something I'm going to add both CMC and a little bit of bentonite (no way to get VeeGum-T ) as a surface hardener (to allow to put more layers without the one below is spoiled). Thank for the tips!
  2. learning to use underglaze

    I have underglazes. At a first I got confused because of the deeply different approach to undergalzes between Italy and US. I never thought that they could be used in any other way but as watercolors, and seeing how it was used many times in the US I thought that they must be two different things, but actually they are not! The only difference is that italian uderglazes are not intended to be used in "the pure form" but only very thinned, as watercolors, so they are in the form of powder (and therefore it does not have any type of thickener or suspending agent) or in the liquid form, but with the wording : "concentrated color, to be thinned with water before use", so they probably have only suspending agent, but nothing that helps brushability or to harden the surface. The main Italian supplier is Colorobbia: http://www.colorobbiart.it/catalogue/?lang=en
  3. learning to use underglaze

    I think that this is what I'm looking for! Actually I don't know the exact composition of my commercial powder underglazes but I think that it doesn't differ a lot from an US underglaze... Unfortuatelly I'm not able to find it in my region... VeeGum-T appears to be a commercial name for smectite clay, that is a very generic name that comprises many different clays... Could bentonite act at the same way?
  4. learning to use underglaze

    Some days ago I noticed to have in my my inventory some Duncan underglazes... I had not used them for so long time that I forgot to have them! I have always used them very diluted as watercolors. With them I made some tests and actually I noticed that they are different from italian underglazes not for the composition of the color itself but just because they (duncan) are problably added with some sort of gum to meke them "brushable" and to form a compact layer. I tried also some italian liquid underglazes and although they don't form a compact layer like Duncan underglazes, it's still feasible to use them like "US underglazes", the only problem is that they are sold in very very small jars (less than 1oz) and to use them in the "pure form" make them definitely not cost effective... In my inventory I have also many jars full of powder undergalzes. I tried to use them to make solid layers but is unuseful to say that is not possible because once dried they return to be powdery and is not possibile to make multiple layers. Does anybody know what I can add to powder underglazes in order to make them brushable and to form a compact layer? Maybe some CMC or other? Of some colors I have some lbs (a lifetime supply if used as watercolors!) and I think it's worth trying to use them like "US underglazes".
  5. Umpteenth question on raku kilns

    Thank you for the reply! In order to ensure enough air moving iside the tiny chamber do you think that some sort of chimney will help? I'm going to keep the control unit, not indeed to control the heating elements (that has already been cut off) but because I need the reading of pyrometer (that probably will be pretty out of calibration but I can compensate it with some try with cones) so I could do without the possibility of peeking through the chimneyf... And anyway i could do some sort of peephole... This is just a temporary solution anyway... In a (I hope not too far) future I will replace it with abigger ceramic fiber chamber... is someone albe to figure out what is the maximum volume heatable with a weed burner with a nominal power of 80 KW (about 273.000 BTU?)
  6. Hi folks! I've just been given to me what I hoped to be my first own electric kiln. It's a very very small stackable top loading kiln. The chamber is more or less a cube with 12"\13" (32cm) side. Microscopic but mine! Unfortunately it doesn't work... () because it's not able to go above 1300F (700°C)... It's too a small and old kiln to spend money to replace the heating elements, even because the control unit is very "primitive" so I would have very small control on temperature rising velocity ecc.. Just to not toss everything, I thought to convert it in a updraft raku kiln. It's a lot of time I've planned to build one raku kiln and I think that this can be a good occasion since I can save the cost of the isolating blanket. I'm little scared that the kiln will be just too small to have an evengas heating but at that point the cost of a barrel and a ceramic fiber blaket will be not so high... I read a ton of threads here and elseware but just I couldn't find out an indication on what the diameter of inlet and oulet should be... I will use a weed burner with a torch diameter of 6cm so I thought to make both the inlet (in the bottom) and outlet (in the lid) of 8cm... I need to buy and use a hole saw (and I want to retain the "scrap") so I want to be pretty sure that I'm not going to enlarge it because are too small... I'm going to put a cordierite"flame spreader" 5cm high above the inlet hole. Somebody could give me some tip or tell me if this stuff will never work properly??
  7. Getting zinged by bisque

    Here I can see no clue... Corundum is just aluminum oxide "doped" with other elements that give its color (in the case of the involved stain appears to be manganese)... sometimes corundum crystalline lattice can be tensioned and cracks because of big doping elements (i.e. chromium in ruby, and this is why it's so rare to have big rubies) but this is likely to happen only in big mono-crystals, and in this case, In my opinion, there is no explaination in the composition of the stain. Some foreign element\agent should be involved...
  8. Getting zinged by bisque

    So weird... Looks like a kind of blistering... the behavior almost seems to suggest the presence of particles reactive to the water, like burnt lime (from calcium carbonate). This defect (even if not always is a defect) can occour in some clays for bricks, roof tiles and other outdoor objects. But hardly I can see this in a stain...
  9. Page 31 appears suggest that potters should perform testing only if they use problematic materials... this is very reasonable, but I do not find evidence in the legislation...
  10. I read online also some rumors (also from Higher Institute of Health members! This in some presentation made for ceramic industry) obut a revision of the directive itself... At least here the result of such a things is that nobody does nothing waiting futher developments... Anyway if something of more detailed for artisanal pottery will follow, for me is well accepted! Anyway a lot of very interesting and useful stuff from all of you!
  11. I think that this due to the fact that the aim of the EU document was primarily to "develop adequate methodologies for testing these articles" insted of make a methodic study about how metal leach s changes as the boundary conditions change... this is something that can be interesting for us (and in this way I will find much more time to study the interesting material posted by @Min. It's the potter that should be interested on how to avoid excessive metals leach. It is sufficient for the legislator to set thresholds that make sense ... isn't it?
  12. Handy Techniques

    The kitchen is my primary source of tools, as for many other people. A wire cake cutter is far more useful as a clay cuter. Pastry rings can be fine to make clay disks. A sturdy aluminium syringe for biscuits is my favorite portable small extruder... needless to talk about the wooden rolling pin ...
  13. One thing is not so crear to me... maybe because I'm little dummy or I paid insufficient attention, but...(I'm referring to the test report found by @High Bridge Pottery Pottery) Hollow articles appeared to be tested in the interior, i.e. they are filled with acetic acid or another test liquid ("The articles were filled with the test liquid to a level no more than 1 mm from the overflow point"). But at p19 also the external surface appears bitten... This is something that is not so clear (to me) also in the EU directives. Do only the internal parts that are destined to contact food need to be tested? Could I (for example) make a mug externaly lead plated but with a safe glaze inside? Another thing... should I test every single shape I'm going to make? Does is not sufficient to test the couple clay-glaze fired at a given temperature? I don't think that there is significant difference between a mug or a bowl if produced with the same clay and same glaze...
  14. I've just read an interesting article (titled "Detailed and Unstructured", Witten by Lori Martin) in Pottery Making illustrated from the Jan/Feb 2018 issue. I find this technique interesting and similar to another technique that I love: cuerda seca... I've just only a couple of doubts... First: does really is possible to apply a colored glaze over a clear glaze (2 coats!) without have the colored glaze leaked\blended? Should I take some precaution in order to avoid problems? It's not the first time I see somebody who does such a "design", but everyone else did not put anything "in the background"... Second: What kind of colored glazes could be used for that job? Expecially for the black outlines... they does not appears as normal "glassy" glazes... The only american brand easily available in my area is Mayco, and I've noticed that some glazes like "stroke & coat" are pretty different from glazes I was used to use...

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