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So, I just read my CAD email about a gentleman who uses a kind of lowfire clay called fritware. Accprding to the description, it was developed in the Middle East to mimic porcelain. Naturally, being the resident lowfiring rodent, I was VERY intrigued! Have any of you, my esteemed fellow artists, used fritware? If so, how did you like it? How's its porosity? Firing range? Easy/hard to throw? Does it take glazes well? It looks like it'd be a sweet body for my underglaze illustrations, but would I be better off sticking to white-slipped terracotta or my current white earthenware?

 

This inquiring guinea pig mind would like to know from personal experiences, not a google search--it's more fun and often more informative, in my humble opinion. ♥♥♥ ^_^

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I do have a low fire question.  I used 05 clay with 05 glaze to make some mugs.  Put water in them and sure enough it seeped out the bottom.  So what clay is non-porous at 05?  I moved to cone 5-6 clay with 5-6 glazes and no problems so that is mainly what I use now.  But I inherited some low fire glazes I would like to use up.

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Well, here's the thing about lowfire. If you're gonna make functional work, you gotta glaze every inch of that piece except the bottom of the foot. My glazes are "technically" for ^05 firings, but I fire them to ^03 to make them a bit more vitreous. The glazes do cool stuff, too. :D

Oh, and when I say to glaze everything, be sure to have space on the bottom of the piece, like a pedestal foot or something. That way, it won't pee everywhere from the bottom. :)

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It's possible to make vitrified low fire bodies using frit as the primary flux, rather than feldspar like most high fire bodies use. Frit 3110 is commonly used nowadays. Most of these types of bodies that I have heard about are not all that easy to work with, and are only good for smaller pieces. Fritware is really high in silica and low in clay, so plasticity is not good.

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Yeah, I did some research on it, and it seems like it'd be very difficult to work with. It has such an unusual aesthetic; I saw some Middle Eastern bowls with beautiful blue and yellow motifs. I also read that some of them contain lead, soooo... I think I'll stick with my white earthenware. :)

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Just read an article about this in Sept 15 Ceramics Monthly issue, I get mine late in the UK, only delivered yesterday. Seems like an expensive way to make clay bodies but I get the idea. 0.4% absorption at cone 04.

 

He talks a lot about the ecological impact of firing to cone 10, I'm not sure about that, surely using a frit comes with its own energy consumption already being pre-melted. In the long run are you really saving that much energy? Maybe I love firing cone 10 a little too much. I have always thought about dropping to cone 6 but the ingredients seem to be 4-5 times as much to get glazing going so does it really save money in the end. Probably but I don't like it :P

 

I would at least try it out guinea, you never know, it might work for you.

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Just read an article about this in Sept 15 Ceramics Monthly issue, I get mine late in the UK, only delivered yesterday. Seems like an expensive way to make clay bodies but I get the idea. 0.4% absorption at cone 04.

 

He talks a lot about the ecological impact of firing to cone 10, I'm not sure about that, surely using a frit comes with its own energy consumption already being pre-melted. In the long run are you really saving that much energy? Maybe I love firing cone 10 a little too much. I have always thought about dropping to cone 6 but the ingredients seem to be 4-5 times as much to get glazing going so does it really save money in the end. Probably but I don't like it :P

 

Frit is not cheap, but even with frit clay is cheap in the big picture. Even at $1 per pound for the clay, your only spending $1.50 on enough clay to make a $26 mug. That's pretty low materials cost.

 

You'd have to do the calculations based on your energy costs and kiln usage, but figure you'll save a dollar or two per firing by firing at low fire instead of cone 6, and you'll triple your element life (or more), which is where some real savings come in. I change the elements on my smaller kiln every year, which at $50 per element means a $600 savings over 3 years. In my big kiln I change them every 20 months or so. Those elements retail for $730 per set, so the savings can add up pretty quick there. It is probably not enough to totally offset the higher price of the clay, but it will definitely help. Also figure that your kiln is going to last a lot longer, so there's a long term savings there. You can also save by buying a less powerful  and therefore less expensive kiln, which will be cheaper to install since the lower amperage will use smaller wires. There will be less waste heat during firings, so in an air conditioned space the AC won't have to work as hard, or you'll be more comfortable working in a non-air conditioned space. There are a lot of little benefits to firing lower, which add up to more than you'd think.

 

I'm not sure what you mean by the glaze ingredients costing 4-5 times as much as cone 10 glazes. Are you referring to the cost of frits? Here in the US, the cost of the commonly used frits can be purchased for about $1.25 per pound. Neph Sye is about $0.90 per pound and G200 spar is about $0.75, so it's not that huge a difference. I have many glazes in my studio that use very small percentages of frits, like under 5%, or none at all, so the cost is not any different if you're careful about formulation.

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All my feldspars, kaolin, silica, whiting, dolomite cost 0.70~ per kg and the cheapest frits I can find cost 4.00 per kg minimum for what they call 'standard borax frit'

 

The only ferro frit I can find is 3110 at 6.14 per kg.

 

I didn't think about element life too much and probably don't have enough experience with kilns to make a good opinion :D I just feel its slightly 6 or two threes. Reducing cost in some places increases it in others. No AC needed in the UK, especially up in Newcastle.

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All my feldspars, kaolin, silica, whiting, dolomite cost 0.70~ per kg and the cheapest frits I can find cost 4.00 per kg minimum for what they call 'standard borax frit'

 

The only ferro frit I can find is 3110 at 6.14 per kg.

 

I didn't think about element life too much and probably don't have enough experience with kilns to make a good opinion :D I just feel its slightly 6 or two threes. Reducing cost in some places increases it in others. No AC needed in the UK, especially up in Newcastle.

 

Bummer on the frit prices! Are they all imported?

 

Here's an example of one of my cone 6 glazes with very little boron (frit). It's a fake ash glaze of sorts, but doesn't run into rivulets. It goes on very nice, and will have matte and semi-glossy areas depending on thickness and how it's cooled.

 

S-4 Blue

Dolomite  1.87

Custer Feldspar  48.56

Whiting  28.01

EPK  12.29

Flint  6.35

Gillespie Borate  2.91

Rutile  4.50

Cobalt Carb  0.75

Red Iron Oxide  2.00

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No idea, I would think they are with those kind of price differences. Adding 33% to clay body or 70%+ to a glaze for the examples supplied in the fritware article just seems like a lot.

 

I may look more into a cone 6 move as anything from 1-5% addition seems reasonable as I can see it like a cheap colourantish thing.

 

Sorry for taking this a little off course.

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I have several cone 10 glazes that I dropped to cone 6 with just 3-6% Gillespie Borate. It's worth testing. If you're firing gas, you can still fire reduction, and your fuel savings will be very noticeable. I've read that it takes approximately the same amount of gas to get up to cone 6 as it does to get from 6 to 10, and I believe it. It takes a crapload of fuel for the last 150F degrees creeping up to cone 10. That's a 50% savings!

 

A little off course, but no too bad. It's all related!

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Gillespie Borate.. replacing Gerstley Borate?

 

Yes. It's a consistent blend of the minerals found in Gerstley, made by Hammil and Gillespie. I have found that it tends to be a bit stronger than Gerstley, so  bit less can be used. You could also test Frit 3134 for bringing down the temp.

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okay, my skills a math are pitiful.  the high school aptitude graph showed all my other abilities above 90 percentile and math at 33. :unsure:

 

BUT, i remember that a kilogram is just over 2 pounds.  today's exchange rate for dollars vs pounds or euros shows the dollar worth   point 65 pounds and   point 89 euro.  

 

how do you do your math, joel?  is it really that expensive since our stuff is priced per pound? :wacko:  not arguing, just curious.

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You don't even really need to do the maths. If you did convert to dollars and divide by 2.2 the price jumps are still about the same ratio to each other.

 

In real terms, a 25kg bag or 55# of feldspars etc is around £15-£20 ($25~) and the frit can go from £100-£150 ($180~) for the same bag. Gillespie is actually a little cheaper if I remember right. More expensive if you don't want 25kg of frit. All suppliers sell the same 6 or 7 frits which are probably all imported now I think about it.

 

No idea what it is like in Europe.

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Old Lady never ventuer out of America to pot! The price of materials for claywork in Aus is similar to Britain, many ingredients required for glazes are priced way more expensive in Aus. Even frits and minerals which are manufactured here!!! The only LOGIC i can even get to is that the market..ie no. of potters is much less.. Don't know. From memory a little tube of ceramic enhancer I think you guys call it costs about $28 here, You buy it below $5 US so even with out the math, it's obvious it's a lot different.

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Cavy, you can make clay bodies yourself to vitrify at any temperature you like really (within reason), You can't buy low fire vitrifying commercially made bodies unless its somoething like egyptian paste. They often lack plasticity which doesn't suit most people who throw or handbuild.  When I  started researching these bodies I started a couple of threads on here (it was about a year and a half ago from memory) and I posted some recipes that I was trying, as did some others. The first thread was called Cone 04 porcelain I think. You can also use recycled glass cullet with is much cheaper than frit. If you have access to university data bases you can find lots of information in the ceramic engineering/industrial journals or dental ceramic research. They have a far greater knowledge of the chemistry and behaviour of clay bodies (probably as they appraoch them from a completely different paradigm) than most of us ceramic artists! They are also more experimental as industrial requirements for ceramics are so different to the requirements of potters and artists (ie ceramics in various technologies). You just need to push and test.  The recipes on the other thread are a good place to start. 

 

Throughout history there have been lots of different iterations of what makes a particular clay body (despite what comtemporary porcelain purists will say) and many large scale crockery producers use lower firing bodies as it speeds up their production, but they have developed their own bodies that are hard enough and durable enough for daily ware.  Its a worthy pursuit to try, even if for nothing other than to understand your materials and their limits better :)

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