oldlady Posted January 15, 2017 Report Share Posted January 15, 2017 not saying anything bad about your great explanation, just joining in on the fun. it is true that many of us do not care how things work, we just want them TO work, our way. reality is a really depressing subject. i try to avoid it at all costs. i like the fact that reality does not scare you, you have the guts to tell the emperor he is nude. pot roast is great. what is your address? Link to comment Share on other sites More sharing options...
glazenerd Posted January 15, 2017 Report Share Posted January 15, 2017 just joining in on the fun. Me too I get the technical jargon, but then again I have spent years studying it. On the other hand, I do not have the skills to make bowls like you or others do. I cannot make the technical pieces like Chris, nor are my throwing skills very sharp: but I am okay with all of that. Like any thing else in life, everyone adds their unique talents. Now for glaze; temmoku is like a thick raspberry compote... Nerd........ Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted January 15, 2017 Report Share Posted January 15, 2017 Now for glaze; temmoku is like a thick raspberry compote... Nope .... Chocolate caramel topping! LT Link to comment Share on other sites More sharing options...
Chilly Posted January 16, 2017 Report Share Posted January 16, 2017 you have the guts to tell the emperor he is nude. We should all be brave enough to say it as it is, but too often life is calmer when we keep our heads below the parapet. I learned to be tactful (sometimes) only a couple of years ago !! Link to comment Share on other sites More sharing options...
bciskepottery Posted January 16, 2017 Report Share Posted January 16, 2017 i like the fact that reality does not scare you, you have the guts to tell the emperor he is nude. Unfortunately, the emperors (e.g., clay manufacturers) likely know this and continue to do so regardless for whatever reasons, including the one we continue to buy what they produce. If they see a benefit to standards, they would have done so years ago. Link to comment Share on other sites More sharing options...
Guest JBaymore Posted January 16, 2017 Report Share Posted January 16, 2017 i like the fact that reality does not scare you, you have the guts to tell the emperor he is nude. Unfortunately, the emperors (e.g., clay manufacturers) likely know this and continue to do so regardless for whatever reasons, including the one we continue to buy what they produce. If they see a benefit to standards, they would have done so years ago. What he said. best, ..................john Link to comment Share on other sites More sharing options...
Chris Campbell Posted January 16, 2017 Report Share Posted January 16, 2017 ... so, the manufacturers call it like it is ... Clay FIVE is Cone 5 ONLY. You just know one of us is going to buy it and try firing it to some other temp. Something to do with brain wiring I think. Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted January 16, 2017 Report Share Posted January 16, 2017 Let's not forget that a firebrick is just a block of an underfired clay body. LT Link to comment Share on other sites More sharing options...
glazenerd Posted January 16, 2017 Report Share Posted January 16, 2017 I do not know how potters in the UK keep their sanity. I have seen many posts stating a clay has a 04 to 6 firing range- IMPOSSIBLE!!! Nerd Link to comment Share on other sites More sharing options...
Magnolia Mud Research Posted January 16, 2017 Report Share Posted January 16, 2017 Our local supplier of Raku clay body claims that it works for raku firings (~1000 C) as well as at cone 10 (~1300 C), and it does! I don't use cone 5-6, so have no data. My point is: It is the potter's responsibility to choose a clay body and a firing condition that meets the requirements of the products they want to make. It may mean firing hotter or lower (or slower) to produce a good product. I use a clay body that makes great flower pots at cone 04, great bowls and cups at cone 3, and a good glaze at cone 10. LT Link to comment Share on other sites More sharing options...
Chris Campbell Posted January 16, 2017 Report Share Posted January 16, 2017 Our local supplier of Raku clay body claims that it works for raku firings (~1000 C) as well as at cone 10 (~1300 C), and it does! I don't use cone 5-6, so have no data. I always used high fire stoneware clay for raku because the lower firing temeprature left the clay body so open that it took the reduction process beautifully. The end product was never meant to be functional and was sturdy enough for decorative uses. I have even used my Southern Ice porcelain in raku just to see what would happen ... the piece lasted over 8 years until the chips started to be too noticeable. ( I kept the piece, did not sell it as I did not think it would not last long.) Link to comment Share on other sites More sharing options...
Stephen Posted January 16, 2017 Report Share Posted January 16, 2017 Thanks everyone. I think I'm going to get to work on that box of cone 6 porcelain. Do I hear groaning? Remember, I'm still a newbie. It's formulated for cone 6 so it's ok even tho it's porcelain right? Nerd, how about a brief synopsis of your rant in layperson's terms? I mean clayperson's terms. Haha. ( do I hear more groaning?) Or just nod if you agree with what's been said. Hi Irene, We've been using a 4-6 mid range porcelain for about six years fired to 5 with 20 minute hold and have not had any problems. Spot on is great but I think 4-6 is narrow enough for what you are doing IMHO. We have sold thousands and use ours daily in our own kitchen. Didn't read whole thread but just build a few vases and fire a couple un-glazed and leave out on a napkin and see if you are getting any moisture after a day or two. If your clay is maturing properly it really should remain completely dry indefinitely if in room temp inside where outside moisture is not building up and running down the pot's outside. Link to comment Share on other sites More sharing options...
bciskepottery Posted January 16, 2017 Report Share Posted January 16, 2017 I do not know how potters in the UK keep their sanity. I have seen many posts stating a clay has a 04 to 6 firing range- IMPOSSIBLE!!! Nerd Sure its possible . . . it just will not vitrify at lower cones, etc. It's not what they are saying, it's what they are not saying. I've fired Standard's red earthenware to cone 6 -- just to see. And the test tile came out fine. Link to comment Share on other sites More sharing options...
glazenerd Posted January 17, 2017 Report Share Posted January 17, 2017 Bruce: point taken... it is possible to fuse any cone at a lower cone..... so let me rephrase It is IMPOSSIBLE to vitrify a clay body across a broad firing range. Porcelain at cone 10 - 3.50% KnaO cone 6 - 3.90%... cone 3- 4.25% it's what they are not saying..... true that.. The potter does need to research their clay of choice and use accordingly. The makers however need to stop making outrageous claims. The label can say: cone 1 through 10, but also note that it vitrifies above cone 8...etc. I would think because of liability issues they would also include: For Non-Functional Use Only. Nerd Link to comment Share on other sites More sharing options...
Guest JBaymore Posted January 17, 2017 Report Share Posted January 17, 2017 I would think because of liability issues they would also include: For Non-Functional Use Only. Tom, You would think that.... BUT... and that is a big BUT......... the ceramic suppliers do not indemnify the end users of their products. So it I buy clay from XYZ Ceramic Supply...... and I make functional ware that explodes in the microwave....... it is MY problem with the consumer that bought that explodo-work from me. I can't defend myself by saying, "Not my fault... it is XYZs fault". I would have to settle with the client myself. THEN I would have to go after the XYZ place to try to recover my losses in the other situation. Separate case. Bet that they can afford better lawyers than I can. And.... their product literature and websites and bills say quite clearly that they are not responsible..... test, test, test, ..........and that it is the end user's responsibility to see if their product is suitable for what they make. So...... I'd lose. Case of "Caveat Emptor". best, .......................john Link to comment Share on other sites More sharing options...
irenepots Posted January 17, 2017 Author Report Share Posted January 17, 2017 Thanks everyone. I think I'm going to get to work on that box of cone 6 porcelain. Do I hear groaning? Remember, I'm still a newbie. It's formulated for cone 6 so it's ok even tho it's porcelain right? Nerd, how about a brief synopsis of your rant in layperson's terms? I mean clayperson's terms. Haha. ( do I hear more groaning?) Or just nod if you agree with what's been said. Hi Irene, We've been using a 4-6 mid range porcelain for about six years fired to 5 with 20 minute hold and have not had any problems. Spot on is great but I think 4-6 is narrow enough for what you are doing IMHO. We have sold thousands and use ours daily in our own kitchen. Didn't read whole thread but just build a few vases and fire a couple un-glazed and leave out on a napkin and see if you are getting any moisture after a day or two. If your clay is maturing properly it really should remain completely dry indefinitely if in room temp inside where outside moisture is not building up and running down the pot's outside. I'm going to try that. Thanks! One each of ^6 porcelain, ^4-6 #112, and ^4-6 #266. That last one is interesting because in one place it's listed as being ^4-6 and another as ^5. Let's see, well the box says. 4-6. I'm going to aim for around 5 3/4. In fact, I bought a box of self supporting ^5 1/2 cones the other day, I've never seen those before. I guess there must have been a demand for them. Link to comment Share on other sites More sharing options...
glazenerd Posted January 17, 2017 Report Share Posted January 17, 2017 John: This topic comes up ever two months or so, with the same ending. Should have stuck with my "mutters". response. Although, I will keep banging the drum in hopes the industry changes. BUT... and that is a big BUT.... Not sure how to respond to this..............<smirks> Nerd Link to comment Share on other sites More sharing options...
Guest JBaymore Posted January 17, 2017 Report Share Posted January 17, 2017 Although, I will keep banging the drum in hopes the industry changes. I've been beating on that drum for a LONG time, Nerd. As long as people buy the product......... and don't complain LOUDLY.......... it won't change. best, .................john Link to comment Share on other sites More sharing options...
Marcia Selsor Posted January 17, 2017 Report Share Posted January 17, 2017 Chilly: I have used food / ovens before in describing the firing process. Sorry, I do not remember what threads they are in. Brownies are much more fun than describing molarity, Si/AL ratios, and heat work. I have already decided to use cake frosting to describe the different glazes.... However, I will continue my push to change the industry standard firing cycles. The trend is to fire to perfect glaze; which leads to an immature clay body: mostly applicable to a cone 6 firing. So I will use a 1" prime rib steak to make this illustration. When you put a spice rub (glaze) on a steak and toss it into a broiler (kiln); the oven will seer the outside of the steak and activate the seasonings; but the inside of the steak is still mostly raw. (medium rare). So when you serve it; the outside looks all juicy and seared until you cut into it; and the blood comes up (off gasses). In order to cook a thick prime rib to well done, you have to cook it (ramp cycle) at a temperature and cycle so the meat is cooked all the way to the center. The more I study this issue; the more I am convinced that nearly 90% of pinholes and craters in a glaze is due to an immature clay body. The current remedy is to do an extended hold: which really does not mature the glaze ( if you notice the samples with pinholes, the glaze is already mature.) The extended hold simply allows the clay to complete its off gassing. Pin holes are a sure sign that the clay body is immature: which increases absorption, and decreases vitrification. Many potters that struggle with absorption, do so partly because of their firing cycles. In addition, and immature clay body can also lead to some COE issues: how a vitrified body contracts upon cooling, and a immature body contracts upon cooling: is not the same. Some fluxes actually cause expansion at high temperatures: and increase articular crazing because they have not fully matured, which would compress (vitrify) if allowed to mature. There are several potters that have struggled with pinholes and craters, and well as some crazing issues that I have helped in PM. They followed my recommended cone 6 firing schedule; which remedied their problems. I will leave it up to them to post results; that is their call. The before and after results are very clear. Sorry John- Neil: could no longer refrain.... Nerd [you did very well. This is a great topic for you to expound.Just control and take a deep breath as said before. I appreciate the technical explanation of the vitrifying to control the pin holing. Go for it and explain away. You do it so well. Seriously. Thank you, Marcia Link to comment Share on other sites More sharing options...
glazenerd Posted January 17, 2017 Report Share Posted January 17, 2017 you did very well. This is a great topic for you to expound.Just control and take a deep breath as said before. I appreciate the technical explanation of the vitrifying to control the pin holing. Go for it and explain away. You do it so well. Seriously. Thank you, Marcia Very kind of you to say- appreciate the encouragement. I process and understand clay/glaze is fairly specific scientific/chemistry terms. I struggle often trying to put it into the perspective of every day use. Tom Link to comment Share on other sites More sharing options...
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