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Fritted Vs Free Borax In Clay Body?


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#1 AnnaM

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Posted 26 February 2014 - 05:05 AM

Hi guys, if using a frit ( in a clay body) that doesn't have borax in it, would adding borax have the same effect as using a high borax frit?

I have been using Ferro 4131 (new substitute for 4108/4110) 30% in my clay body to lower its vitrification point as my kiln only gets up to cone 03, but obviously frit is expensive and I have been reading articles where researchers have used recycled glass powdered to 325 mesh. I've looked at the compsition of both and the main difference is that the recycled glass obviously doesn't contain borax, and the extra proportion is made up with silica (frit = 12.73% boric oxide & 59.5% silica / glass powder= 70% silica).

Would adding borax to the glass powder work the same way in the clay body as the boron frit does?

And how essential is the borax for fluxing in that instance?

#2 Marcia Selsor

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Posted 26 February 2014 - 07:53 AM

If you can find Lithium carbonate that is the purest flux.Not sure it will be any less expensive.
You may try Gerstley Borate also.
Both will flux at the lower temperature.

Marcia

#3 neilestrick

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Posted 26 February 2014 - 10:28 AM

Borax is soluble, which is why we don't generally use it in glazes. You want the glaze materials on top of the clay, not absorbed into it. This is why we use frits instead- they have already fused the boron into a non-soluble form. If you were to use it in a clay body, you would probably lose some of it during the throwing process and throw the formula out of whack.

 

It would be worth trying the recycled glass powder. If it melts at a low enough temperature it may not matter if it's a boron base or not. Do you know the melting point of the glass?


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#4 Tyler Miller

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Posted 26 February 2014 - 12:15 PM

You could make your own frit with the borax and glass powder, or you could tailor a frit that even better fits your needs from borax and other glaze ingredients. Safety gear is a must (safety glasses, face shield, leather apron, sleeves, and steel toes), because heating glass up and dumping it into water is obviously dangerous, but it's a simple operation.

 

  Melt your batch in a crucible (I've used a raku kiln as a heat source with kiln furniture I was about to retire) and dump into water which will shatter it or at least make it easy to break.  After grinding and sifting, you have a frit that you can use as normal.



#5 neilestrick

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Posted 26 February 2014 - 02:22 PM

I'm also not sure what effect, if any, it would have on the plasticity of the clay, or if it would migrate out to the surface during drying like salts do.


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#6 Colby Charpentier

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Posted 26 February 2014 - 05:35 PM

Here is a link to the September 2012 Techno-file on Boron in Glazes, which gives good background information on what boron is, how we use it, and all that. I studied with Matt Kattz just before the article was writen, and at the time I was working with Boron to try to activate Iron as a flux at lower temperatures, but running into these soluability issues, even when sourcing Boron through a compound formed with one of the Boron Tetrahydride anions...

 

http://ceramicartsda...Glazes_0912.pdf

 

In any case, I'm of the opinion that commercial clay is a really good option here, especially with the abundance of bodies formulated for use at c04.

 

If you are looking at recycled glass, though, there are plenty of borosilicates commonly used, that would easily source your Boron, although I'm not sold on formulating bodies with home-made frits. It sounds like a nightmare in terms of cost and time...

 

Good Luck!



#7 AnnaM

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Posted 27 February 2014 - 01:31 AM

Thanks guys, I really appreciate your help. Im not sure of the melting point of the glass powder, I received a sample today to muck around with but the data sheet supplied doesn't say what the m.p. is, I'll try and get hold of them tomorrow to ask.

I've put a test tile with a couple of grams in with a low bisque fire to see whether it melts to give me some idea and Ive made up a small bit of my normal clay with the glass powder instead of frit which will go in later tonight. I'll let you know whether it seems viable (with or without more testing).

Am I roughly right in assuming that if the m.p. is low enough on its own, I wouldn't need to worry about boron at all?

I'm fritting my clay because I've found that (down here in Australia at least) none of the commercially available white earthenware clays stand up to the everday knocks and bumps in the kitchen, but if I use a fritted clay, I can get a tighter stronger body which seems to me (just from using it in the kitchen) much closer to stoneware strength. Plus I have the added benefit of brighter colour.

Im crossing my fingers that this works as the glass powder is only $2/kg ;-)

#8 AnnaM

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Posted 27 February 2014 - 02:37 AM

With regards to plasticity Neil, I find no problems with up to 30% frit, so I'm hoping the same for the glass powder. The tiny bit I made up this morning didn't feel any different than it normally does with the frit.

Oh and there's not a snowflake's chance in hell of me even entertaining the notion of making my own frit!!! I'm super impressed at Tyler making his own, but even the thought of it terrifies me!!

#9 neilestrick

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Posted 27 February 2014 - 02:14 PM

With regards to plasticity Neil, I find no problems with up to 30% frit, so I'm hoping the same for the glass powder. The tiny bit I made up this morning didn't feel any different than it normally does with the frit.

Oh and there's not a snowflake's chance in hell of me even entertaining the notion of making my own frit!!! I'm super impressed at Tyler making his own, but even the thought of it terrifies me!!

 

I meant the soluble borax affecting plasticity, not the frit. I was unclear there.


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#10 AnnaM

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Posted 28 February 2014 - 06:28 AM

So the little test cup that went in with the glaze firing is completely vitrified with the glass powder in it. The lack of boron seems to not matter :)

#11 neilestrick

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Posted 28 February 2014 - 08:50 AM

So the little test cup that went in with the glaze firing is completely vitrified with the glass powder in it. The lack of boron seems to not matter :)

 

Excellent. Will the glass supply be consistent in formula? Time to test glazes with it!


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#12 AnnaM

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Posted 28 February 2014 - 05:22 PM

I'll check on that. It's a good point. I use underglazes at the moment (Chysanthos). Will the lack of boron affect the brightness of the colour I wonder?




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