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curt

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  1. Every bit is good! Look forward to seeing the results.
  2. Pres I like your question and understand that my comments here are offered in the spirit of provocative analysis rather than attempting to invalidate the issue. Maybe I don’t need to say this, but this topic may be emotive for some. Theft is a pretty strong term. Almost makes it seem like there was something private that you have taken away from the owner without permission. I do not view cultural symbols, icons or art in this way. They are in fact public, meant to be seen, acknowledged and interpreted by others. Further, “cultural theft” may almost be a contradiction in terms. Culture cannot be owned. On the contrary, it is a shared construct. Its manifestations are an invitation from insiders to outsiders to engage and participate. A culture’s ability to survive and thrive depends critically on its ability to be communicated and understood - and potentially adopted, or adapted - by those coming to it for the first time. Those treating culture like a secret birthright that only the high priests can discuss are missing the point. Success is where everyone is discussing it, learning it, sharing it. However, since art is a primary vehicle for communcating culture, using imagery or symbols from a culture other than your own in your artwork, possibly out of (cultural) context, is risky business. If misused, or possibly even when appropriately used, it could be misinterpreted, or seem like a cliche’, or possibly offend those who (legitimately) identify with those symbols as part of their own personal value system. A bit akin to driving without a license, or sufficient training or experience - you probably just shouldn’t be out there. Objects may be closer than they appear.
  3. Note: OK, struggled for quite a while to get this photo to upload, first time doing it with new software update. Tried to upload to my gallery several times with different file sizes but no joy. Every time I hit "submit photos" button after uploading, nothing happened (ever). If anyone can point me to instructions would appreciate it. As promised from tiles above back in mid-March, this is the same glaze as above, but in oxidation (electric), and probably fired to around cone 9 (cant say for sure because I did not fire it.) Most distinctive feature is still the stark divide between not so much zircon (2 left columns) and too much zircon (3 right columns). Other than that, this glaze in oxidation appears to be behaving very similar to reduction, with the obvious difference that the light iron content here is making the glaze brown, rather than green as it did in reduction (see tiles above). The bottom 4 cells of the middle column are probably the most interesting to me after looking at this for a while. I am tempted to do another tile that zooms in on this area to see what is really happening when the zircon/silica is changed in much smaller increments. At some point between columns 2 and 3, the zircon is going to appear on the scene. I know zircon is very refractory, but I can't tell (even after looking with 800x zoom microscope) if the zircon is just sitting in this glaze doing nothing but looking white, or if it is getting moved around, dissolved, or otherwise homogenized into the melt. Obviously small amounts simply vanish, as we can see from the two left-most columns. The original glaze is around corner D, basically matt white. I am waiting on one more refire of the reduction tiles above and then I will post them again, maybe with a bit of compare and contrast if I can manage to organize the photos.
  4. I pug clay. There is no pressure. Nothing that must be done. No finish line. No phones, no computers, no TV. No control. The pug mill tells me how fast to go, gently ignoring any pleas to go faster... Just lovely plastic handfuls of clay, Iike the first time you touched it. In. Out. In. Out. In. Out. The mineral earth smell, cold and damp, squeezing through my fingers. Slap into the hopper. Down comes the plunger, extra force applied right to the bottom to leave no doubt about who is really in charge of everything in this little world. Endless, rhythmic repetition (cut, smash, cut smash, cut smash), the low steady drone of the motor, the slow but inevitable extrusion of perfect worms, again, and again. ... hypnotic....like a wheel going round...and round.... ...the mind wanders, ... sequences of thoughts lead strangely down side paths. Ideas occur, new but vaguely familiar, coming from somewhere like things that happen in a dream. Forms appear in your minds eye, once known, then forgotten and now rediscovered... have hours passed or only minutes? No idea. Cut slap smash. It goes on. You are far away now. a distant call to dinner shakes you awake.. back to earth. switch off the pugmill. As the dream fades you quickly you scribble down a few thoughts, rough out a shape or two... tomorrow is another day. As you drift off you know fresh pugs of clay wait silently in a neat stack, filled with possibility, daring you to try something new...
  5. However, understand that “dry” doesn’t necessarily mean leaving a pot just sitting out on a shelf somewhere. If you live in a climate that cycles through wet and dry seasons, and cold and hot temperatures extremes, humidity levels in the air can also move up and down substantially over time. This affects things made out of clay which have not yet been fired. Dry pots absorb and desorb lots of water from humidity in the air, through the small channels in and around clay particles. Unfired clay effectively inhales and exhales humidity over time. Think of it a bit like a rigid sponge. This matters because clay shrinks and swells as it’s water content changes. While most of the shrinking happens in the day or two after we take a pot off the wheel, shrinking and swelling stresses are still at work in a small but meaningful way even when we think of the pot as “dry”. And different temperatures also promote water movement, in the pot as a whole, and also in different parts of the same pot. Humidity fluctuations may or may not matter, depending on your clay body and what is in it. Big, gutsy clay bodies which are relatively “open” ie a good range of large and small particles sizes with grog, silica sand or other aggregate strengtheners, along with sufficient colloidal material may have very good “dry” strength. Fine porcelain bodies have larger smaller particles, greater surface area, and smaller pore channels, but little in the way of aggregates to strengthen the body, and can be more fragile. Different clay body ingredients can also impact how well a clay body withstands humidity cycling. Sodium Bentonite, for instance, which shrinks and swells dramatically, is a common clay body plasticiser, and small colloidal particles like this are actually the main source of green strength in dry pots. It is mostly not a a problem since our clay bodies have so little of it, but should not be forgotten, as some bodies lean on bentonite more heavily. Ball clay shrinks and swells less than bentonite, but there is usually a lot more of it than bentonite in clay bodies we use. Point of all of this is that pots can be negatively impacted by humidity cycling, and to a lesser extent temperature cycling, causing weakness, cracks which show up later during glaze firing, and in extreme circumstances even dry pots disintegrating where they sit. The longer you leave them exposed, the greater the risk. The extreme version of all this would be if your studio is in a rainforest, and you leave a pot on top of the kiln you fire every couple of weeks, and which is also exposed to the sun on one side. That should be the perfect storm. Moral of the story is if you want your dry pots to last and fire OK later, try to avoid putting them through conditions like this.
  6. Some new currie test tiles here. Testing a slightly modified version of the basic ash glaze in Britt's High Fire glazes book. I have used this glaze several times in both oxidation and reduction, with some promise, and wanted to run some currie tiles to explore variants. However, these tiles were all from the same firing in a small LPG kiln which, in the main, did not get to temperature. Target was cone 10, and some parts of the kiln may have reached cone 8 or 9, though, including one of the tiles below. However, the two cone packs(8, 9 and 10) did not budge. This is a non-standard currie tile. It was a bit tricky to do a currie tile with this recipe because silica is not a specified ingredient in this glaze. The closet thing to silica was the zircon (the only non-flux beside the kaolin), so that is what I used in place of silica for the currie tile. I also adjusted the amount of silica (er, zircon) down from 50 to 18, because zircon is so refractory. So when you look at the tiles, remember that where you are expecting to see silica, it is zircon instead, and much less of it than what the silica normally is. In the first three pictures below, I am going from most fired to least fired as we go down. The original base glaze recipe is very close to what you see in cell 4 in these tiles. Clearly it needs to get hotter to get properly fired. Even though this glaze is underfired, I wanted to share it because there is some interesting information here. First, and probably most dramatically, there is a sharp break between the left two columns and the right three columns. This is almost certainly the opacifying effect of the zircon. Next, I was surprised to see that the meltiest (or maybe just the glossiest?) point of these tiles was consistently around cell 17 or 18. Usually corner C is the best melter. Probably an artefact of the non-standard set up for this tile... Also, as we go down you can begin to see the striding figure in each cell near the bottom of the tiles. This surprised me, as it is almost all flux down there (corner C is 50% ash, 50% neph sy). So why that would be melting later than cells which have much more kaolin and/or zircon in them is something I am still thinking about (thoughts?). Plenty of surface tension evident in the top two rows, and maybe even down into the third row a bit. Many cells were raised and puffy, with apparently still a lot of off-gassing to do. Also plenty of little off-gassing holes in the glaze surfaces in many cells. Finally, the last picture are some test tiles with this glaze, mainly in reduction. These tiles DID get to a full cone 10 or thereabouts. Interesting yellowish color on right tile, which is on white stoneware in reduction. The right two tiles both have a slightly even more modified version of the basic ash recipe that has additional neph sy. Interested in thoughts or reactions. Also, I have one more tile with this glaze which I hope to fire soon. Hopefully that one will get to temperature! Will report back with that later.
  7. I find the six o’clock mark useful when I am not sure which cells will melt - or how well - and want to have an ex-post indicator. It also gives some indication of how well the glaze heals over. Every cell on your grids appears very well melted so that is not surprising. In fact I suspect that was kind of the point with the oil spotting (ie, to have very fluid melts) so mission accomplished. So Pieter just to be clear, is there iron in the far left column or not? The range you quote above suggests there is? And it does look like there is from the pics. Just want to be sure. Does this mean that bubbles are forming as the kiln cools? I am having trouble understanding how, on the one hand the glaze is too stiff to allow bubbles, but on the other hand it is fluid enough to heal over? Will think about this some more. I think you are on the right track on this. Corner A (high alumina) is in the good glass region looking at the Glazy chart above. Corner C (high iron low alumina) could be smooth because it is forming a different kind of “glass” due to the iron content which is more much more refractory in oxidation. The way the iron “bubbles” to make the oilspots in every cell on the grid is different to the bubbles formed occasionally by off-gassing of other, non-iron clay or glaze materials. However, returning to corner C, I think the big bubbles there are due simply the massive amount of flux (and barely any alumina or silica) in that corner, probably low-melting flux (?), which is simply boiling and boiling away even long after the more “balanced” cells on the grid have stiffened up, and a lot of the way down as the kiln is cooling. Maybe. I don’t remember if you have posted the specific recipe or not, or what else is in the glaze.
  8. Looks interesting. I can imagine three levels/depths of glaze, maybe cascading down from high to low if the glaze is fluxy, or sticking to three seperate levels if too stiff to run?
  9. I would happily run vertical tiles for every one of the 35 glazes on a standard Currie grid if it were not so much work. I am sure it would lead to the discovery of a bunch of interesting glazes that I am missing now because I do not go this extra step. Alas, it does take extra work - producing blank test tiles, firing them, etc. but the biggest problem I really seem to having even selectively running vertical tests is that my standard 300g corner batches do not really generate enough glaze in the cups to properly dip a test tile later. Also, since the delay between initially mixing up the cups and later wanting to run the vertical tests is often a few weeks, I find I usually have to kind of reconstitute the glazes in each cup to get them the proper consistency. More time, and then if I add a bit too much water, well, now it is too thin. I am thinking I could do a better job of using ALL the glaze in the corner batches into the cups, giving me more to work with in each cup, ie more to dip into with a vertical test tile. Or maybe I could mix bigger corner batches in the first place and have more to work with. Or maybe I could decant the glaze from each cup after mixing into a purpose-made, perfectly-fits-the-shape-of-one-vertical-tile kind of cup that maximises the glaze coverage on the test tile. I know that some here have gone the opposite direction by mixing the smallest possible corner batches so as not to waste raw glaze materials.... but I am probably headed the other way, as it is enough work and time to do a Currie grid that I am not worrying about wasting a few bucks on materials. Anyway, still thinking about this. One thing I HAVE done with some of the leftover corner batches and cups so as not to waste them is to remix subgroups of cups and corners to make a smallish batch of a whole new glaze which approximates the chemistry of one of the cells. This has worked to some degree. If you mean on vertical tiles I agree. I think the biggest value of the 100% flux cell is when it is on a flat Currie tile for comparison purposes. That 100% cell gives a clear idea of what the glaze looks like with NO added alumina and NO added silica, so we can get a sense of how the glaze changes when we start adding those materials (which make up the majority of most glazes). More generally, I would say this is true of a number of the extreme or peripheral cells on a Currie tile. They are not so much “glazes” as they are visual points of comparison - and thereby information- on the cells in the interior space that we are probably more interested in as viable candidates. I am (trying) not (to be) a purist on Currie’s method. I know we have collectively made improvements to it already and I agree with you that there is more to be done. Yes! We have to keep pushing it, testing it, rethinking it - and ultimately making it better.
  10. Below some comments I made earlier in this thread when we were discussing currie tile design last year. Not sure how much is relevant to your current line of thinking on this topic, but wanted to put it out there again. What is not here is the later "rooks" discussion - an attempt to combine a horizontal currie grid with vertical test tiles in one go to get some additional verticality - but that is also amongst the last few pages of this thread, you may remember it. My only general thought on the recent discussion just above is make sure you don't ask too much of the currie grid! :-) The horizontal nature of the grid delivers definite benefits in my view (see below), and raised portions in every cell may obstruct the ability to harvest those benefits to some degree. I guess it kind of depends on how raised you are talking about, ie much further than the raised portions currie already included? Seems you are saying yes to that if your initial pictures are an indication. If you do make the little mountains you are talking about in every cell, will they be hollow underneath the tile? If not those mounds could be pretty thick compared to the rest of the tile, and represent extra thermal mass in that part of each cell which distorts how the glaze on the mound behaves somewhat. Also might distort the glaze around the mound to some degree. Would this matter? Not sure, but just saying it may not replicate the vertical surface of your pots in this case, as this extra thermal mass probably amounts to extra heatwork on the glaze. On the other hand, maybe that is extra information, lol. Your call and will be interested in whatever you decide to do.
  11. Definitely keep posting the tiles - and your interpretation of what you are seeing. Very interesting and informative. Every Currie tile is a great learning opportunity, even if it is a glaze I don’t happen to be working on at the moment.
  12. A few more comments after a second careful look at these two copper/SiC tiles. I do like the second, third and fourth looks, because I am less distracted by colours and better able to hunt for the patterns and other fruit currie is offering up. First, suggest if possible you treat SiC as a flux in your calcs for this glaze. My take is that the second tile is overall noticeably more fluxed than the base tile. Specifically, compare cells 16 and 21 on both tiles. The SiC tile is much more crazed in those cells, making it more like its neighbours below. To me crazing is a sign of excessive flux (or, lol, not enough alumina and silica :-)) . In fact, overall the entire first column is much more fluxed on the SiC tile. Also, the whole right hand two columns of each tile compared, where we see the base tile very bubbly and crusty, and the same columns on the SiC tile smoothed out - pitted and bubbled yes (as you would expect with greater fluxing?) - but nonetheless flattened out, like the melt has been better or more complete anyway. On a "standard" currie tile with "standard" fluxes I think you would normally be looking for the "best" quality glass in cells 13, 14 and 15, and in cells 18, 19 and 20, where the alumina and silica are in about the right ratio, and with the right amount of flux to get the job done. However, in both your tiles, the good glass cells are much father over to the left as you have identified. This suggests to me that this glaze is very silica sensitive, and too much silica is just not a viable glaze, or more specifically, does not produce a good homogenous melt. Finally, very interesting to see where the red is in the SiC tile. At high flux levels, there simply is NO reduction red appearing. In fact, you could almost draw a line across the tile from the upper left to the lower right as the "reduction boundary", ie, combinations of silica and alumina that DO allow the reduction affect to occur, ie, where you can see red just starting to appear. Interestingly, at the bottom of this boundary, in the bottom row of the SiC tile, the red only appears in cell 34. Maybe it would have appeared in cell 35, but looks like this cell may not have melted properly. This all suggests to me that there is minimum silica and alumina that is needed to produced SiC copper red? Also, that this glaze is VERY sensitive to silica....
  13. Maybe what this guy suggested? Just substitute the word “copper” for “iron”? Lol. Maybe. However, looks like those right hand side SiC cells are kind of pittted, no?
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