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docweathers

Red/pink/purple/mauve

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ChenowethArts    461

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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PeterH    87

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.com/-MU9RxpvpkaU/TgyN0isRdJI/AAAAAAAAAAU/D6uyUC3-HQo/s1600/LineBlendFirstFiring.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://mainekilnworks.blogspot.co.uk/2011/06/iron-red-test-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.)

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Norm Stuart    80

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.ning.com/forum/topics/iron-glazes-and-achieving-red-color-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.com/-MU9RxpvpkaU/TgyN0isRdJI/AAAAAAAAAAU/D6uyUC3-HQo/s1600/LineBlendFirstFiring.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://mainekilnworks.blogspot.co.uk/2011/06/iron-red-test-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.)

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docweathers    79

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

MSDS High Purity iron oxide red.pdf

MSDS High Purity iron oxide red.pdf

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Norm Stuart    80

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

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