fergusonjeff
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PeterH reacted to a post in a topic: Granular Feldspar
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Not all rock chicken grit is feldspar. I got some from another potter that worked, but all the chicken grit (rock kind, not shell) I can find now is granite. Can add interesting texture but does not melt even up to cone 12.
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Finn, As an archaeology professor who does lots of experimental work , I am curious to know more about your project. What are you planning to do? I would be happy to try to produce the pieces for you, but shipping to the UK would be prohibitive. An old knapper friend of mine delivered concrete to the Coors (yes the beer company) plant. I guess during prohibition the company started producing specialized ceramics. He would go through the massive waster piles and get some interesting knapable pieces. Worked like a slightly grainy chert. Only real problem was it would produce a very loud ring when flaked that would require hearing protection. I am not sure if standard cone-10 porcelain would have the same density as the stuff Coors makes. .
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Piedmont Pottery reacted to a post in a topic: Problem with Peter Pugger not De-airing Clay
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Hulk reacted to a post in a topic: Problem with Peter Pugger not De-airing Clay
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Problem with Peter Pugger not De-airing Clay
fergusonjeff replied to Sasha Hill's topic in Equipment Use and Repair
The dip in pressure you are getting is the vacuum finally getting to the mixing chamber. When the mixing chamber is full and you are mixing mode, there is a seal of clay that forms between the back chamber (where the vacuum port is) and the mixing chamber. When you start pugging it allows a small gap to form along the mixing shaft that then removes the air from the mixing chamber. This is more pronounced if the mixing chamber is overstuffed. After getting the vacuum established in the rear chamber using mixing mode, I switch to pugging mode and slow speed. Usually where there is about 4-8 inches of clay out of the nozzle the seal will break that releases the vacuum into the mixing chamber. Keep slowly pugging until the gauge shows the vacuum back up. then reverse direction to mixing and allow the extruded clay to be sucked back into the chamber (be sure to replace the cap). After a few second of mixing, then return to pugging and extrude the full batch. Usually, the first 6-8" has some minor bubbles so that just goes back in the next batch (or I keep that aside for handles and other attachments). -
animal bones shards as stilts for stoneware?
fergusonjeff replied to Emilio's topic in Studio Operations and Making Work
Peter, I may be reading it wrong, but I think the original poster was referring to using bone and shell as wadding rather than as posts. Shells work great for wadding during the firing, but within a few days turn to powder. I imagine bone would be similar, but maybe less structurally stable during the firing. Jeff -
Mg versus Ilmenite granules in clay
fergusonjeff replied to Kathryn Howlett's topic in Clay and Glaze Chemistry
Excellent question, and I am looking forward to responses. I think it depends on the temp you are firing to. My understanding is the granular manganese is better at cone 6 (melts and of-gasses too much at cone 10) and granular illmenite (or magnetite) work better at cone 10. -
neilestrick reacted to a post in a topic: New to me Geil Kiln
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Thanks for the advice on the copper reds. Fired again yesterday and went with heavier reduction. Still too hot to open early this morning, but a quick peek showed some nice red test tiles. More reduction and thicker glaze seemed to help.
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Neil - the copper reds were going green where thick. So I think I need both heavier reduction and thicker application. I ended up going past cone 11 throughout the firing. Would the higher temp cause issues for the reds? Mark - Let me know when you are ready to pass on your old 12x24 advancers. Definitely in the market when you are ready.
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Mark, thanks for the info. Just peeked into the kiln this morning and the shelves looked fine. Still too hot to unload. This is my second time firing a gas kiln (used to wood and electric) and based on the quick peek at the copper red samples I am still not getting enough reduction. Hopefully I can get that worked out. I am definitely interested in the shelves. I would like to get about a dozen at least. If the price is right then shipping in small batches or meeting up somewhere would be great. Jeff
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Mark - Question on the quick cooling. I have a new (to me) 14 cu ft olympic gas kiln. I have only fired it once before and have it loaded to fire this weekend. I have two new bailey shelves in the stack to try them out (I really like the advancers in my electric kiln). The kiln cools fast on its own (can open the next day). I am not opening anything to purposely crash cool but it is a fiber-lined softbrick kiln that just cools quickly on its own. Would this pose any danger to the shelves? I have them in the middle of the stack right now but plan to keep adding more over time. Thanks.
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Callie Beller Diesel reacted to a post in a topic: Using Lidar to calculate volume of an object
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JohnnyK reacted to a post in a topic: Using Lidar to calculate volume of an object
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Rae Reich reacted to a post in a topic: Using Lidar to calculate volume of an object
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Babs reacted to a post in a topic: Using Lidar to calculate volume of an object
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Min reacted to a post in a topic: Using Lidar to calculate volume of an object
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Just a little additional clarification, LiDAR works by continuous scanning from all angels and would require more than a single shot. The background would not really matter because it is not using the visual image but laser detected distances in a large point cloud. You would then have a large data file to export to some processing program. Might be a lot easier to just have a series of boxes and the smallest one it fits in is a specific price.
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Min reacted to a post in a topic: Glaze Bucket Failure
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I also get my Tin from them and it has always been fine.
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For my main 3 glazes I got big 20-30 gallon tubs from the farm supply store. Have held up well for over 5 years. got cheap furniture dollys from Harbor Freight and just added slightly larger wood tops. made covers from plywood. I have used square 4-5 gallon icing buckets for all other glazes. The square shape is better for dipping most items than round buckets. Get them free from Sams Club.
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another kiln shelf question
fergusonjeff replied to fergusonjeff's topic in Equipment Use and Repair
Thanks Neil. That is what I was afraid of. I have been really happy with my 26" half round advancers at cone 6 electric. Just hoping there was a better solution than $5000 all at once. -
I am currently mostly firing a wood kiln and use 12x24" silicon carbide shelves that have held up well through about 30 firings. I am planning to build a gas (cone 10) kiln that will use the same size shelves. I would like to start buying 12x24 advancers, but at almost $300 each that is too much at one time. I plan to fire lots of flat plates and flat shelves are critical. I know there was some discussion of the nitrile bonded shelves with the cuts, but I don't remember if they are reasonable substitutes for advancers. Here is a link to some that are only $100 per shelf. https://nmclay.com/lgrf330-shelf-sil-carb-nitride-bonded12x24x-394 Any thoughts? Thanks, Jeff