I tried a glaze recipe called "Orange Street" with Yellow Iron Oxide (which fires a light orange) with Red Iron Oxide Precipitate.
http://powenliu.blogspot.com/2011/03/cone-6-glazes.html
130.3% ORANGE STREET ^6
46.8% Feldspar F-4 Soda
17.9% Gerstly Borate
15.2% Silica
13.8% Talc
12.0% Bone Ash
8.1% Dolomite
4.5% EPK
12.0% Red Iron Oxide Precipitate
6.2% Yellow Iron Oxide or Crocus Martis
I've found "red iron oxide" comes in a variety of purity. The one from Standard Ceramics beats Laguna hands down as it is pure red iron oxide and doesn't contain barium sulphate. Laguna Red Iron Oxide tends to fire brown to dark brown in our kiln at Cone 6.
Firing to Cone 6, the Red Iron Oxide Precipitate remains stable - except on thin areas of the ware which receive more heat where it breaks down to Black Iron Oxide. I'll be comparing the Standard Ceramics "precipitate" with "Special Red Iron Oxide" from U.S. Pigment.
These tiles were fired to Cone 6, held for 30 minutes and slow-cooled at 50F between 1,800F and 1,500F. A differing firing cycle could change the resulting look of the glaze.
I have the special iron red oxide from ceramic supply and pricipitate on order from standard. I made up a 100 gram batch using special rio and I subbed purple ochre for the yellow rio. I know I have crocus martis as I have made van gilder red before but I couldn't find it. I have a chip in a firing as we speak so I will see what it looks like by Friday.
I got my RIO Precipitate from standard today so I can mix up another small batch. I'm wondering if I should try & find my crocus martis or stick with the purple ochre. I was in a hurry last night & wanted to get the test piece in with the other pot so I didn't look as long as I could have. I guess I could have gone to the local supply and gotten yellow RIO. I also have a bag from Ruelev(spelling?) that is an artist supply house. It is a Red Hematite. I have done a couple tests in other glazes with it & it makes things come out more reddish-purple. So many tests, so few test tiles!
I used Yellow Iron Oxide, which supposedly just 88% of Red Iron Oxide. The LOI being water, hydroxyls.
I went into this believing the H20 firing off the Fe2O3.H2O is not relevant, and probably isn't.
But I've already been surprised already that one ingredient or another can make a glaze difference in the relevant Cone 6 range when you're not first firing to Cone 10. I have an open mind at the moment.
My tests came out more almost glossy than semi-matt. Of course this was on a heavy iron clay shard. Has anybody tested on white clay or porcelain? I like it well enough that I'm going to mix some up on Saturday and spray it on a pot. It is really a nice glaze. I will be testing it with some different subs on the yellow iron oxide and also compare the special RIO as opposed to the precipitate. Jhp
Norm Stuart
http://powenliu.blogspot.com/2011/03/cone-6-glazes.html
130.3% ORANGE STREET ^6
46.8% Feldspar F-4 Soda
17.9% Gerstly Borate
15.2% Silica
13.8% Talc
12.0% Bone Ash
8.1% Dolomite
4.5% EPK
12.0% Red Iron Oxide Precipitate
6.2% Yellow Iron Oxide or Crocus Martis
Mar 18, 2013
Christopher Cisper
I like this glaze alot! Is it fairly stable? And how is red iron precipitate different from red Iron oxide?
Mar 19, 2013
Norm Stuart
I've found "red iron oxide" comes in a variety of purity. The one from Standard Ceramics beats Laguna hands down as it is pure red iron oxide and doesn't contain barium sulphate. Laguna Red Iron Oxide tends to fire brown to dark brown in our kiln at Cone 6.
Firing to Cone 6, the Red Iron Oxide Precipitate remains stable - except on thin areas of the ware which receive more heat where it breaks down to Black Iron Oxide. I'll be comparing the Standard Ceramics "precipitate" with "Special Red Iron Oxide" from U.S. Pigment.
These tiles were fired to Cone 6, held for 30 minutes and slow-cooled at 50F between 1,800F and 1,500F. A differing firing cycle could change the resulting look of the glaze.
http://www.standardceramic.com/Materials.html
Other posts on this subject:
http://cone6pots.ning.com/photo/img-0380?commentId=2103784%3ACommen...
Mar 20, 2013
Jeff Poulter
Mar 20, 2013
George Lewter
Mar 21, 2013
Jeff Poulter
I got my RIO Precipitate from standard today so I can mix up another small batch. I'm wondering if I should try & find my crocus martis or stick with the purple ochre. I was in a hurry last night & wanted to get the test piece in with the other pot so I didn't look as long as I could have. I guess I could have gone to the local supply and gotten yellow RIO. I also have a bag from Ruelev(spelling?) that is an artist supply house. It is a Red Hematite. I have done a couple tests in other glazes with it & it makes things come out more reddish-purple. So many tests, so few test tiles!
Mar 21, 2013
Norm Stuart
I used Yellow Iron Oxide, which supposedly just 88% of Red Iron Oxide. The LOI being water, hydroxyls.
I went into this believing the H20 firing off the Fe2O3.H2O is not relevant, and probably isn't.
But I've already been surprised already that one ingredient or another can make a glaze difference in the relevant Cone 6 range when you're not first firing to Cone 10. I have an open mind at the moment.
Mar 21, 2013
Jeff Poulter
Mar 21, 2013