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curt

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About curt

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  1. 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.
  2. curt

    Seeking Advice

    I would be very relaxed about this student interaction. Progress is an individual matter, and relative to the individual themselves. We all progress in our own ways, and according to our own capacities. More advanced students helping less advanced students is positive, unless this is for a serious grade or something. Ultimately, fellow travellers helping each other on the journey is a beautiful thing. Treasure it like gold.
  3. curt

    Impurities

    Most likely a bad batch of mugs, maybe a problem in the casting process? Judging by its location and intensity, that contamination in the pictures looks like impurities in the slip casting clay or the molds. It is too concentrated and deep and localised to be contamination you are introducing in handling at your end, or from your kiln environment. They are specks, not smudges, so unlikely to be handling contamination. Also, the slight fuzziness around the spots and the way they are breaking (at least on the mug handles) through the glaze surface suggests to me that they are a significant contamination (some kind of metallic based crud) coming from the surface of the clay itself, which is poking up through the glaze. Or possibly, but less likely in my view, contamination in the glaze itself (but the pattern of specking is too particular to be from the glaze in my opinion.) are you glazing them yourself of do they come pre-glazed? If unglazed, I might try washing the mugs carefully and examining with a magnifying glass around the rims and handles. Also maybe if unglazed try firing one without glaze and see if it happens.
  4. curt

    What kind of clay am I digging up

    Test all three levels. Form marble sized balls of each. Make sure they are bone dry and dry them in the oven (slowly) for an hour or so at 105 degrees Celsius to be sure they really dry. Just fire marble sized balls of each in some kind of container in the kiln to the hottest temp you guy. Note if they melt or not
  5. curt

    What kind of clay am I digging up

    Have you tried firing some in your furnace?
  6. curt

    Why is glaze blue

    Phosphorous in the bone ash may also be contributing to the blue. The blue looks far too uniform to be cobalt flashing to me
  7. curt

    Chattering

    Pres I made exactly this point about 7 posts up from yours . Let me add that I have extensive personal experience with dull trimming tools. And I inevitably get even more experience periodically when I procrastinate on sharpening those tools. Every so often, when I have completely run out of sharp trimming tools in my workshop, I have to stop whatever else I am doing, get out the bench grinder and spend a morning sharpening them all up. Let it be said that I own few (if any!) high quality trimming tools, mine are almost exclusively Chinese cheapies which I purchased when I didn’t know any better, inherited from others or been gifted, so I don’t mind taking off plenty off metal with the bench grinder (which makes up for a lack of finesse and precision with sheer brutal grinding power). I can tell you that sharpening them up this way DOES make a huge difference, so if you have access to a bench grinder and a healthy supply of cheap tools give it a try. Mind you, I don’t think I would do this with high quality tools, which I would hand sharpen much more carefully. A dull grinding tool, a pot which is too stiff (a stiff leather hard or beyond), and wheel speed which is a bit too fast is the perfect way to propagate chattering in my experience. My take is that this is because the dull tool just bounces over the clay surface rather than cut in. As you try to press harder to get the dull tool to dig in, you can risk damaging your pot if it is delicate, and the chattering often just seems to get worse! Sharp tool is often the solution.
  8. curt

    Chattering

    I think dull tools can also contribute to chattering. Make sure your tools are sharp.
  9. curt

    Hudson River Clay

    Hi Tom, the Mineral Analysis Mary provided is on a % Weight Ignited Basis. This means they have done this analysis AFTER burning to either 750 C or 950 C (which probably explains why there is still so much sulphur left). The components sum to 100.01%, so there is nothing unaccounted for. Not sure where your 2.35% is coming from? In any case, I can confirm that they have definitely not reported an LOI. Based on other clay mineral analysis lab results I have seen, I would guess the actual LOI of this clay is something like 7% or 8%, and possibly more depending on how much organic matter it contained. This would make a big difference if one is plugging this analysis into, say, Insight to play around with glaze formulations. Edit: As someone said above, this material looks chemistry-wise a lot like Albany Slip, which has an LOI of around 9% to 9.5%.
  10. curt

    Hudson River Clay

    Hi Tom, here you mention a 2.35% LOI for Mary’s clay. This seems very low. Just wondering where this number came from?
  11. curt

    Hudson River Clay

    Hi Peter your link is to Currie’s first book on the topic and not the one to look at if you want to start exploring with his method . The book to look at is his second one on the same topic called “Revealing Glazes Using The Grid Method” (has a green cover). It is MUCH easier reading and much better organized than the first book. Very practical Mary if you looked at the first book here no wonder you thought it was not applicable.
  12. Ah yes, one of my favourite topics. Where is the border between porcelain and stoneware, anyway? When does stoneware become so porcelain-like that it “could almost be mistaken for porcelain?” Where indeed! While you waiting for real answers/suggestions from our cone 6 contingent, you may wish to amuse yourself by browsing a thread on these forums entitled “Stoneware Limit Study” started by Glazenerd, in which such matters are thoroughly reviewed...
  13. All too complicated! And no don’t throw them out! Wouldn’t bother with additives unless you specifically need them. 1. (Deleted - not a good idea). 2. Let your glaze bucket sit for a while and water will evaporate off. 3. Let your glaze bucket sit for a while and you will probably be able to scoop or sponge water off the top. 4. Forget the dairy products! Find out what specific gravity your glaze should be a figure out how to measure that, either from these forums (search) or from somewhere on the web. 5. Flocculate your glazes. Again, see many discussions on these forums and in pottery books on this topic. But note that this can only partially address excess water (specific gravity) problems. Bottom line is that your glazes should be the right specific gravity in the first place.
  14. curt

    Hudson River Clay

    Mary my thought is that you would substitute in the Hudson Clay for the clay normally used in a glaze recipe (maybe that is what you mean). However, in his book currie does make some specific suggestions for testing wild clay. Will see if I can find that.
  15. curt

    Hudson River Clay

    Mary, one of the things you need to know as you go down this road is the Loss on Ignition (LOI) for your Hudson clay. Do you know this number? LOI is how effectively how much of your clay goes up the chimney as organic burnout and volatile gases when you fire a dry sample to (usually) 1000 degrees Celsius. It is calculated as a weight % by a before and after weighing. Normally it would be reported on your original lab analysis but I did not see it there, and I have not seen it mentioned anywhere in this thread. If you don't see it you may call back the lab and ask them, because it is clear they ignited your sample, but unclear if they tracked this number. If not, you can carry out the test yourself in you own kiln, but it is better to get the lab's official number if they have it, because they do it more precisely. The absence of the LOI (which is a part of the chemistry of the clay) may explains why the precentages Insight shows are slightly different from what your lab analysis showed. Did you enter any number in the LOI box when inputting your chemistry into Insight? If so it should be reported on the picture above just under Expansion.
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