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red/pink/purple/mauve cone 6 oxidation

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#21 docweathers

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Posted 12 January 2014 - 09:29 PM

Where does US pigments natural iron oxide fit into this?

I agree with that I agree that one needs to be picky about one's glaze Ingredients, but how do you know  where the best ones are? You think a company like Laguna would not be supplying second-rate materials, but obviously they are. I know you can run tests on everything, but that would be an overwhelming task. At some point you've got to figure out who you can trust and who you can't. Can we make a list of quality suppliers? If I understand right, we can put US Pigment at the beginning of that list. Who else can we add?


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#22 docweathers

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Posted 12 January 2014 - 09:44 PM

You revelations have certainly save me a huge amount of time figuring out why my glazes were turning out so brown and drab.

 

Are there any other glaze materials that you done similar research on and found problems?

 

I used to buy all of my stuff from Laguna. A few months ago Jon Brooks and I cross swords.  Since then I buy nothing from Laguna . This revelation puts the final nail in their coffin. I think you have him pegged right.  He also has no prospective on how potter social networks operate and what a bad reputation my cost him.


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#23 docweathers

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Posted 12 January 2014 - 10:54 PM

Thanks and Ugh!

 

 I have some Laguna Cornwall Stone I bought maybe a year ago, which I presume must be from the new mine.


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#24 docweathers

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Posted 13 January 2014 - 06:40 PM

 

I've not been able to get an MSDS sheet for the synthetic red iron oxide from Sayed at US Pigment, which doesn't please me, but his "Red Iron Oxide (High Purity)" does fire the reddest. He says it comes from China which has some Bayferrox licensees as well as companies using the Bayer process without license.  As for his regular grade red iron oxide, just like his "High Purity", see if you can get Sayed to send you an MSDS.  When I spoke to him it was like he had no idea what I was talking about, which isn't possible being in his business.

 

The next best is Standard Ceramic's Iron Oxide, Red, Precipitate which is Bayferrox 140.  A lot of East Coast US vendors buy from Standard Ceramic.  http://www.standardc... Red Precip.pdf

 

As you can see Laguna Clay has a number of MSDS sheets for Red Iron Oxide, ranging from the absolute worst from Rockwood Pigments to Promindsa products, the company which makes the "Spanish Iron Oxide" every vendor in the US sells.   I've asked Juan, the Tech Support lead at Laguna, if they can't carry Bayferrox or some other synthetic red iron oxide, but the answer is no.  If I or someone else could talk with Julie Brooks personally I'm sure the answer could be different.  I just don't think Jon realizes there's such a huge difference in these products - he just strikes me as a self-perceived shrewd negotiator looking for the good deal.

http://www.lagunacla...y/mirox4284.pdf

http://www.lagunacla.../miroxspain.pdf

http://www.lagunacla...ry/miroxr03.pdf

 

What I found particularly annoying is how long it took for me to figure out our problem with red iron glazes and to trace it  back to bags from Laguna.  That's when I began reading MSDS sheets.  Even worse Laguna charges more per pound for an unknown red iron oxide that fires ugly than US Pigment charges for their unknown which fires red. With US Pigment we have to pay for shipping which wouldn't be the case if I could just get Laguna to carry a synthetic red iron oxide.

 

New Mexico Clay and several other vendors sell Bayferrox 132 as Crocus Martis - a product that hasn't existed for many decades.  But 132 is a smaller granule product which can result in heat degradation.  Jeff Poulter tried some and found it fired less red than the Standard Ceramic synthetic.  This could also be what US Pigment sells as "Red Iron Oxide (Pink)".

 

This is a test tile of "Floating Red (Oxblood Red)" with synthetic red iron oxide from Digitalfire (aka Amaco Ancient Japser) over a layer of Amaco "Firebrick Red".  You can clearly see that Firebrick Red is a pigment like a Red Mason Stain rather than an iron oxide glaze.  http://www.digitalfi...oatingblue.html

54.88%  Gertley Borate

14.63%  Talc

30.49%  Silica

21.95%  Red Iron Oxide

med_gallery_18533_643_1163547.jpg

 

 

Where does US pigments natural iron oxide fit into this?

I agree with that I agree that one needs to be picky about one's glaze Ingredients, but how do you know  where the best ones are? You think a company like Laguna would not be supplying second-rate materials, but obviously they are. I know you can run tests on everything, but that would be an overwhelming task. At some point you've got to figure out who you can trust and who you can't. Can we make a list of quality suppliers? If I understand right, we can put US Pigment at the beginning of that list. Who else can we add?

 

Here is a google drive link to a folder with all the MSDS sheet for all of US pigments iron oxides  https://drive.google...Nzg&usp=sharing.

 

Since I don't know what I'm looking at with these things, I would appreciate your reaction to the high purity iron oxide.

 

Larry


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#25 docweathers

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Posted 13 January 2014 - 10:00 PM

Oops, I told you I didn't know what I was looking at.

 

In the Fe304.pdf  it has "Synthetic Iron Oxide" .... I thought that was a key term therefore the relevant PDF. I wrote Syed again and asked if I could also have the high purity MSDS. I probably won't get it but it's worth another try.


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#26 Marcia Selsor

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Posted 13 January 2014 - 10:59 PM

Here is a link to my gallery for Michael Bailey's Iron Red ^6 Oxidation with a lithium wash.
http://community.cer...ailey-red-6-ox/ Thicker is better.

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#27 ChenowethArts

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Posted 14 January 2014 - 05:31 AM

To Norm Stuart (and others)... Thank you! I cannot begin to tell you how much I appreciate the information on red iron oxide. The commentary and images are very compelling.  I cannot wait to do tests with my glazes that are red iron oxide heavy.

My best to you all (spoken in my finest suthun),

Paul


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#28 PeterH

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Posted 14 January 2014 - 08:15 AM

Lots of valuable information to digest. However can I point out that, unlike many other colourants, the colour

achieved by iron red can be quite concentration-dependent. In particular there seems to be a sweet-spot of RIO

concentration (for at least some iron-reds) whose location doesn't seem to travel well. So in addition to using a

"good" RIO, it may be worthwhile to do a line-blend.

 

This picture is of Bailey's Red Line Blend 8%-14% Red Iron Oxide

http://2.bp.blogspot...FirstFiring.jpg

... notice that 1% change in RIO makes a huge difference to the colour near the sweet-spot.

The picture is taken from this page:

http://mainekilnwork...firings_30.html

 

Regards, Peter

 

Obviously a 10% change in the concentration of Fe2O3 in your RIO is about a 1% change in the glaze. So even if

the contaminants were totally innocuous their presence could still have a significant effect on the colour achieved.

(Equally obviously some contaminants such as Mn are strong colourants in their own right.)



#29 Norm Stuart

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Posted 14 January 2014 - 05:02 PM

Red Iron Oxide glazes fired above 2,250 F to cone 10 in a gas kiln, especially with any reduction at all, face entirely different problems. 

 

More, if not all, of the red iron oxide will have lost oxygen and have been converted into black iron oxide.  So in order to end up with a red iron oxide the kiln temperature needs to linger between 1,800 F and 1,600 F while cooling to create red iron oxide.  I can't imagine the barium in Laguna red iron oxide being favorable to the development of red iron oxide, but I've never done this so I don't know.

 

Down-firing to make red iron oxide glazes -- http://cone6pots.nin...or-in-oxidation

 

Firing red iron glazes in oxidation to Cone 6 or below, the red iron oxide you start off with is the red iron oxide you end up with, so you want to start off with a synthetic red iron oxide with large particle size and high purity.

Lots of valuable information to digest. However can I point out that, unlike many other colourants, the colour

achieved by iron red can be quite concentration-dependent. In particular there seems to be a sweet-spot of RIO

concentration (for at least some iron-reds) whose location doesn't seem to travel well. So in addition to using a

"good" RIO, it may be worthwhile to do a line-blend.

 

This picture is of Bailey's Red Line Blend 8%-14% Red Iron Oxide

http://2.bp.blogspot...FirstFiring.jpg

... notice that 1% change in RIO makes a huge difference to the colour near the sweet-spot.

The picture is taken from this page:

http://mainekilnwork...firings_30.html

 

Regards, Peter

 

Obviously a 10% change in the concentration of Fe2O3 in your RIO is about a 1% change in the glaze. So even if

the contaminants were totally innocuous their presence could still have a significant effect on the colour achieved.

(Equally obviously some contaminants such as Mn are strong colourants in their own right.)



#30 docweathers

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Posted 17 January 2014 - 04:42 PM

Attached is a PDF version of the MSDS for US pigment's  high purity iron oxide.

 

 It looks good to me but I don't know what to make of the "C.I. pigment red 101" part of it. What does that refer to what does that refer to?

 

I would like to hear what more knowledgeable people think of it.

 

Larry

Attached Files


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#31 Norm Stuart

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Posted 17 January 2014 - 06:35 PM

That's very pure red iron oxide, which shows in the glaze.   The names are essentially synonyms.

 

Fe2O3.a is red iron oxide in the most common alpha rhombohedral structure.  This has a CAS number of 1309-37-1.

 

 

C.I. (Color Index) Red 101 is actually,  CAS 90452-21-4,  or synthetic Red Iron Oxide with bound moisture.  The resulting compound Fe2H2O4, which reduces to pure Fe2O3-a (red iron oxide) and H2O, is iron (Fe+) weakly bound to a hydroxyls (OH-) leaving a very porous surface area to aid flow characteristics and prevent the red iron oxide from becoming an aspirated nuisance dust.  It is a Chinese maker as Sayed said - now I have the MSDS.  Thanks.

 

Yellow iron oxide has more hydroxyls, being (Fe(OH)3).

Attached is a PDF version of the MSDS for US pigment's  high purity iron oxide.

 

 It looks good to me but I don't know what to make of the "C.I. pigment red 101" part of it. What does that refer to what does that refer to?

 

I would like to hear what more knowledgeable people think of it.

 

Larry



#32 docweathers

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Posted 17 January 2014 - 06:41 PM

I'm glad that turns out to be good stuff since I bought that in a bunch of other stuff from US pigments today.

 

Larry


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