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PatJ

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About PatJ

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    Newbie

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  • Gender
    Male
  • Location
    New Mexico, USA
  • Interests
    Beginer Potter interested in earthenware
  1. Hi all, Has anyone here ever made or used micaceous cooking pottery? I have been making some micaceous pottery but I have never put them to the cooking test. Guess I am a bit scared to. The pottery that I have been making is from clay which i have dug up myself. I have been told by some more experienced mica potters that you don't need to add any additional temper since the clay is already infused with mica and it should work fine as is for cooking. However I have noticed that a lot of historic and prehistoric micaceous pottery and broken pottery sherds that i have been fortunate enough to examine appear to have MUCH MUCH more mica in them. Also many of these old pots also have quite a bit of volcanic sand of various sizes incorporated into their clay bodies. My question is: Do I need to add more mica and/or sand to make my pots more suitable for cooking. Also I have read some old archaeology articale that indicated that these pots were not fired to the point of being fully vitrified. Should I be under firing them for the purpose of using them for cooking? Also does anyone have any recommendations on how to best cook with them. I know that historically they were used over a fire, and I have seen references to prehistoric mica pots being placed on top of 3 stones which elevated it over a hearth fire, but I have also seen a photo of one placed directly on to a hot bed of coals. I have also seen a photo of one cooking away directly on top of a modern gas stove top burner. I know people who make micaceous pottery, but i don't know anyone who actually USES it for cooking, which I know was its primary purpose before metal pots and pans became available here in the American southwest. Any thoughts, advice, comments? PatJ
  2. frustrated

    Thanks. This explanation was very detailed and very insightful. It has also made me worry about some of my other practices. I was taught that when working with micaceous clay, you let it become bone-dry, then sand it, then slip it. With the exception of this last experience, this system has worked for me. However, the thought of leaving internal micro-cracking is a bit unsettling. I would like to get away as much as possible from any practices that could cause excessive micro-cracking. I like the idea of slipping the pot when it is leather hard, but then that leaves the questions of how do I sand the pot then? Sanding after slipping would sand away the slip before it ever erased the imperfections on the paste surface, correct? This is an issue I have with a non-micaceous clay that I am also experimenting with. Any attempt to slip it after it is dry seems to crack it so I do it when it is leather-hard which works, but then I don’t want to sand it because I am afraid to grind off the slip. I have not perfected my skill to the point that I think I can get away from sanding, but I am working on perfecting my skill. Also another issue is when I do sand this non-micaceous clay it smoothes out the clay surface, but reveals lots of bumps (exposed temper) which is another reason why I am tempted not to sand this type of clay. Do you have any thoughts on this? One last question; when slipping a spherical pot, would it be better as a means of reducing micro-cracking so simply reduce the number of times I slip the inside? Very much appreciated Patj
  3. frustrated

    Hi Chris, Yes, I will be recycling them. They were bone dry and had been sanded and were sitting on my shelf waiting to be slipped for almost 2 weeks. I'm just flabergasted because I have been doing the same routine for over a year; slipping and polishing, inside and out, all in a single evening and then warming them in an oven the following night to prep them for firing and this has never failed me. I usually wait about 15 or 20 minutes between adding slip coats and I almost always add oil at the end to give it a little extra shine. I have another cooking pot that is almost dry. I will slow things down a bit. Slip only the exterior one night, the interior another, and then maybe oil it a third night. Maybe this will work. Anyways thanks for your comments. Very much appreciated. Patj
  4. frustrated

    Hi everyone, Thanks again for all the tips that you have sent me on some earlier messages. I have a new question. It seems kind of freakish to me. Last night I was slipping 2 of my pots (I do hand coiling and don’t use a wheel). 1 bowl and 1 cooking pot, both micaceous clay bodies which I have dug from out in the woods. Let me tell you what happened. So I was working on the bowl; I slipped the outside 4 times with a non micaceous slip and then stone polished it to a real nice sheen. Then I slipped the inside 3 times with micaceous slip. I then began softly stone polishing this, not so much for a shine but just softly to smooth out the texture. I rubbed it a few times and then bam! It cracked into 3 huge sections and is only barely holding together. So then I went to work on my cooking pot. I slipped the outside 4 times (I usually wait about 15 minutes before applying a second coat; the micaceous slip dries fast) and buffed it with a cloth. Then I slipped the inside 3 times and then smoothed out the texture by lightly polishing with a stone. Once this was done I applied some vegetable cooking oil in very small amounts to the exterior surface and then began polishing with a stone (I do this with most of my pots). Next thing I know I have 4 cracks that just appear, one of which runs nearly a 3rd of the way around the body of the pot. All of the cracks are on the external surface and don’t appear to have transferred to the internal surface. I have been working with micaceous clay for a year and this has never happened before. This is a very strong clay body and once the pots have managed to pass the drying stage, they are generally in the clear and slipping and polishing are never a critical thing to the structure of the pots. I didn’t do anything different then what I normally do Sorry this message is long. The only thing that I can think of that was different is that we are in the monsoons right now and it was actually raining the night I was doing all this (and it was cool and humid). New Mexico (where i am at) is very dry with VERY low humidity but that night it had been pouring all day. Did this have something to do with it? Any thoughts? The cooking pot is no longer saleable, but is it still usable for cooking? Or is it a total loss too?
  5. Hi Folks, I have a new question. So the work I am doing is primarily with micaceous clay. I love this medium an it is really satisfying. The 3 ways I am firing are pit firing, putting the pots in a metal box "kiln" elevated above ground surrounded by wood, and also putting them out in the open on a 50 gallon drum lid and surrounding them with wood and/or dry cattle dung. What I am doing is not really high temperture stuff in comparison to what most of you do. Now to the question. I want to build some clay tiles (kiln furniture) to lay in the bottom of my metal box and also on the drum lid to keep the pots off the hot metal bottom. Also I wish to make a bunch of bowl shaped bases molded in the puki i have and use those to cover up my pots when i am not using the metal box so that the burning wood doesn't come into contact with the pots. I know that i am supposed to use old broken pots to do this job, but since i am relatively new to this art form, I don't have enough broken pots to actually do the job so I need to make some supstitute pieces. Since I don't want to use my precious micaceous clay, which i had to dig up and process myself, to make these tiles and bowl shaped forms (I want to save the mica clay for actually building pots and not waisting it as "Kiln furniture", I was hoping to find some commercial clay that i could use to do this job. FINALLY THE QUESTION IS THIS: is there a commercial clay that I can buy that can fullfill the role of Kilm furniture and being able to withstand numerous firings in direct contact with hot metal and also can survive being in contact with burning wood during pit firing? I was wondering if Raku clay would do this? Sorry this is long and thanks for any insight you all might have. PatJ
  6. Hi Folks, I'm new to this forum and to pottery making so please forgive me for not knowing some of the basics or some of the terms. I was testing the suitability of a new clay source I found out in the woods by making several small test pots. I dug up the clay, added varying amounts of Tuff (volcanic ash rock) temper and fired them in a pit (no kiln). They were not slipped or polished. Today I decided to test how waterproof the pots were so i filled one (this one was made with 40% temper) with water and left it sitting for about 10 minutes. Now I totally expected that the pot would be super porous and water would leak out big time, but what I didn't expect is that the pot cracked in multiple spots all starting at the rim and working their way down. Also when I tested the strength of the wall of the pot, a whole fragment/sherd broke off along a crack. The wall body had become soft, which I never would have expected since it was fired a couple of months ago. Does anyone know why this pot cracked and the paste body had become soft? Was there too much or not enough temper? Is it the clay itself? Was it not fired hot enough? Any suggestions would be appreciated. Thanks!
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