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GreyBird

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Everything posted by GreyBird

  1. Thanks Rae!!! Yes, I am excited
  2. OK, looks fabulous on the squid vase... and a second Hudson River clay glaze recipe on a few other pieces... It's been almost a year since I started down this rabbit hole. I think I can lay these to rest now and get back to production!
  3. OK, well it's 7PM and it's only at 400°. I guess this is going to have to wait until tomorrow morning.
  4. I'm tracking temps in my latest firing. I have an old Norman Electric Kiln. I found I needed to slow the heat rise in the last portion of the firing but It cooled steadily at 100° per hour which is plenty slow and that's with kiln vent on. At that rate it should have been cooled to 300° by 2pm today but it seams to have stalled at 11am around 700° since at 1pm it was still at 700°. I opened the vent and still it only dropped 50° in the next half hour to 650° so I also cracked the lid and we're down another 50° in a half hour. I'll check it again in an hour but as it cools the cool down really slows to a crawl! It's killing' me!
  5. So do think the orange color on the plain clay part is coming from some sort of soda ash or baking soda in the glaze?
  6. Yes! Go to Croton Point, park in the big parking lot facing the playground. Walk in past the playground parallel to the river. You'll be walking South. When you come to the end of the field you'll see a path/dirt road that goes up and to the left a bit. Follow that up about 100 yards and you'll see a path on your right which leads down to the river. Now just keep walking South along the river and look to your left. There are many places where trees have fallen over and you can see the clay entangled in their roots. Also where the walls of the river get steep and high you will see clay there. You'll need to check the tide chart and go at low tide. I imagine if Croton Point is not close to you you can probably find the same anywhere that you have the river walls exposed. PS... I had the clay analyzed and it came back surprisingly clean
  7. Its funny how things work out sometimes... I had posted a photo from a book a while back which pictured a "rust red"platter. I had to take the photo down as it was copyrighted, but the discussion talked a lot about obtaining the red I was looking for that I saw on that platter. I had given up on the idea after many failed tests. And subsequently moved on to develop the Hudson River Clay glaze. The last tile I pictured here in this post showed some really great rust red blooming from the dark glaze. I fired that in my test kiln and matched the heat rise and fall of my large kiln, or so I thought. Until I went to run these two mugs when I noticed that after it reached temp I had the numbers put in wrong and the kiln actually cooled much quicker than it would have in my large kiln. So I fixed the error and let the cups fire with a slow cool of 190° per hour to like 1490 the let it cool the rest naturally. The results were a rust red alternating with shiny black very similar to that elusive platter red I was trying to achieve. I do have a question in all of this... Notice how the clay appears stained reddish from about 1/2" from the bottom up. I'm sure the cups were clean when they went in and not sure where this discoloration is coming from. could it be that the Iron soaked from the glaze through the clay? Maybe if I cool at 200° per hour or let it cool naturally next time it'll have less time to soak through?
  8. Oh boy, good to know. Thanks! And thanks for the video!
  9. Don't the numbers along the top of the chart represent cones? so, 02, 01, 1, 2, 3 etc.? If this is true then simply adding more Silica to a Matt glaze not only makes it glossy but should also move it's firing temp up? Unless I misunderstood those numbers along the top of Matt Katz's chart. Your chart just says cone 10 along the top and does away with those numbers.
  10. Thank you Neil, good point. I agree.
  11. Hmmm, very interesting Bill, I never even thought to look at it using the glaze software. And here I just learned so much about glaze chemistry, I should have. I just assumed, since it was in a book, it would be correct. I'm looking at it now... doesn't the ratio: Si:Al: 4.7:1 put it firmly in the Stull chart as melting at cone 6 as a Semi Matt Glaze?
  12. So I brought my favorite glaze into class to show my teacher what I was going to do color tests on. Keep in mind she is not a glaze chemistry teacher but she is a very good at teaching throwing & hand building. She quickly pointed out that my favorite tile is full of pinholes. I was astonished. I could not see them at all. I actually thought she was pulling my chain but she was insistent and kept pointing and looking real close and saying "yup, they're there." I kind of wanted to poke her in the eye. I did not. After class, I went home and got my magnifying glass and a flashlight and did a close inspection and there are pinholes. This, of course, made me look at the rest of my glaze tiles more closely and low and behold my very favorite satin color, Cobalt Green, has a bunch of pinholes! Yikes! How did I miss that? and why... why, why, why. I went online and started looking at ways to fix. I'm guessing it's a glaze issue since it only happens with some glazes, not all. If it were a clay body issue it would happen to all. I thought I might try a Satin Matte glaze such as Pikes Purple and switch out the colorants but we all know that will never go as planned. Curious to how Cobalt could be producing such a beautiful Green, I was reading on DigitalFire about Cobalt it mentions that it sometimes causes pinholes. So now I am thinking if I switch out the colorants, not only will that not work, but I'll just have the same issue. Anyway just using the colorants in another recipe would be yet another rabbit hole and I 'm currently thoroughly ensconced in my Hudson River Clay rabbit hole for now. Any Ideas Anyone? Would maybe a 5 minute soak fix this? Here is the Cobalt Green Recipe & Photo. Also attaching a photo f the tile that started all the pinhole hoopla: Neph Sy: 64.8 Spodumene: 13.9 Gerstley Borate: 4.6 OM-4: 7.4 Whiting: 4.6 Flint: 4.7 Cobalt Carb: 1 Rutile: 2 Bentonite: 2
  13. OK, I think I just can't give up the experimenting bug. So now I'm thinking what colorants will work well with this glaze? I am going to try what is used for Waterfall Brown in "Mastering Cone 6 glazes". It makes a lot of sense since this clay has such a high Iron content and waterfall brown utilizes that. So I'll add 3% Red Iron Ox since the clay already has 7% and 1% Rutile. Should be fun! Hmmm, also I wonder what would happen if I added Opacifiers. Maybe I need to do a triaxial blend with it
  14. Hi Babs, I usually throw a large low casserole type shape about 2" or 3 " then remove a circular section of the bottom while it is still on the wheel leaving about a 1/2" foot. When it firms up a bit I just slice it up, stamp each piece for so I can see how it breaks over a pattern and cut holes for hanging in the top with a simple hole cutter. This way they have a little foot to Stand upright in the kiln and they hang nicely on a chord. I have to make more, I'm fresh out! Its also good to make them in Porcelain and stoneware as the glazes act so differently on Porcelain.
  15. Thank You Neil! "oldlady", I know you are kidding, right? I'm still experimenting. LOL.
  16. OK, happy day! I have finally gotten to running more glaze tests. I am Soooo very excited about the results. Here are three new tests of the Hudson River Clay glaze. I wish the sun was out so you could really see the color variation better. I was able to re create the original that I loved so much with the toasty edges (3rd tile) the first tile is what I'd expect from the clay after seeing what others have done with it. But the second is a whole new happy accident! Whoa, what a feast of reds to black on this one ❤️❤️❤️ Now I'll mix up a large bucket of those two favorites and retest to make sure I'm still on target before I put on any pieces... But I'm pretty sure I've turned a corner on this long road and finally got my own beautiful, unique glazes made from local clay.
  17. Good luck to you too! I'm at the point where I am realizing there are no shortcuts. Even with my recipes that have nothing to do with local clay... I really ever only needed a few good bases (Gloss and Satin Matt) then from there I can develop my bank of colors and combinations instead of just mixing glazes willy nilly from found recipes.
  18. OK, I know this is probably getting old for folks, but I thought I had a good grasp on things after I took the online glaze calculation course and developed my last batch of Hudson River Clay tests before I went away for a little over a month. After coming back I realized that I couldn't remember why I did what I did so I went back through the class lectures where needed, and realized I had some funky ideas in place and couldn't trace where they came from. So I re-examined the formula. In order to reach R2O:RO: 0.5:0.5 In order to fire to cone six, I only need to add 10% whiting & 10% Lithium Carb. That lands me squarely at .5/.5 Not sure how it will pan out in reality but when I looked at the ratio of my last batch where I added 30% whiting it was way off. It was at .1/.9 The other which was 30% whiting, 10% Gerstley Borate & 10% frit 3124 was also .1/.9 I'm surprised they worked at all. So back to the basement to make more test tiles! Yikes. This clay naturally starts with a .3:.7 ratio so that's amazing. The Alumina is quite high. The Si/Al ratio is 5:1 but that's still on the Stull chart. It should work. We'll see.
  19. I see now what my error was in mixing the Hudson River Clay glazes and yes, it seams I mixed them all improperly, not just the one that looked obviously bad... When I altered the ingredient amounts to make the correct is/al ratios the batch no longer ads up to 100 so you can't just add your additional ingredients in grams and then the rest in Hudson Valley clay to make the batch add to 100. So I had HRC30 which is HRC with 30% whiting so 1000g of HRC and 300g of whiting NOT 70g of HRC and 30g of whiting. And so on... HRC103010 should be 1000g HRC, Gerstlry 100g, whiting 300g, frit 3134 10og easy enough to fix... just need to add the additional HRC to each. Thank God!
  20. I wish I could claim such a knowledgeable origin to the idea behind the piece, but I can not. I just did what I felt to do and there you have it. LOL.
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