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Comment by Jeff Poulter on May 13, 2013 at 1:55pm

Hi Norm,

    In the Orange Street I used the 140 & 180, but there was some contamination with the Rublev Hematite.  In the Penland I used 180 & in the C Harris I used the 140.  Next they will go in a bisque.  jhp

Comment by Norm Stuart on May 13, 2013 at 1:40pm

Interesting results. I asked Lanxess for samples of several types of Bayferrox.

I'll try some small batch glaze tiles when our kiln is running again.

These are the products in your tests and mine.

0.17 micron Bayferrox 140 94.2% Red Iron Oxide - aka "Ceramic Supply Special Red Iron Oxide"

0.30 micron Bayferrox 130 94.2% Red Iron Oxide - aka "Ceramic Supply crocus martis"

0.70 micron Bayferrox 180 97.3% Red Iron Oxide - aka "New Mexico Clay crocus martis"

For your "Orange Street" glaze did you use 12% Bayferrox for RIO and 6.3% Yellow Iron Oxide in place of "crocus martis" as I did, or did you use 12% of Bayferrox 140 and 6.3% of Bayferrox 180 as "crocus martis"?

I'm not sure exactly what yellow iron oxide does in a glaze melt, but it certainly has a lot less iron.

Comment by Jeff Poulter on May 13, 2013 at 12:09pm

These were fired in a Skutt KM-818.  Fast fire to ^5 with a 15 min soak.  125C ramp down to 962C with a 30 min hold(normally I do 60).  I was reading an old post yesterday the talked about it being better to get the time in the 800C-1000C range on the way up, than on the way down or even in a re-fire for that matter.  In that 150C to 200C window, you are clumping together the converted hematite crystals & they don't run into as much interference since you haven't hit the higher temps where the other colors of crystals are produced.  When you re-fire in a bisque you are maximizing the time that you are in the hematite crystal range, especially if you are doing a slow bisque, but they are competing with the other colors that have already been produced.  I guess I will do a glaze program that goes really slow through that range on the way up & then still do a rather quick cool in the range where that other crystals are produced & then do an hour hold at 962C. That will be my next try.  So many shards, so much testing, so little TIME!  jhp 

Comment by Jeff Poulter on May 13, 2013 at 11:57am

This is the C. Harris Tenmoku.  Smack dab in the middle between the other 2.  More orange than Penland & more red than Orange Street.  More metallic & orange on the dark clay & will probably go more red on a re-fire.  Very smooth & glossy.  Glossiest of the 3 tested.

Comment by Jeff Poulter on May 13, 2013 at 11:53am

This is Penland Red-Orange.  The most red of the 3 with a fair amount of black.  Don't know what it will do in a re-fire, but I will find out when I do my next bisque.  Slight pin holing on the porcelain.  Less on the dark clay.  Probably would have been smoother on a slower cool.  Also probably more red as well. Better in real life than on the shard.

Comment by Jeff Poulter on May 13, 2013 at 11:46am

OK.  Let me preface the photos with a couple conditions.  Because of the pots loaded in the kiln. I didn't do as slow a cool as I would have liked to, cause I didn't want a mass of crystals on the 2 pots.  I cooled at 125C/hr & only held at 962C for 30 minutes.  Also on the Orange Street, I mixed up the new batch with what was already in the container, so there was some cross-contamination from the old batch.  Here are the pics: This Orange Street.  A lot of green, but the most orange of the 3.  More metallic on dark clay.  If I re-fire to ^04, it will go more red.

Comment by Norm Stuart on May 13, 2013 at 10:33am

Jeff - I received another reply about "crocus martis" which reveals how information gets lost in the supply chain.

http://www.clayworkssupplies.com/index.cgi

Hi Norm,
 Our crocus martis does say Bayferrox on the bag, but it doesn't have a number included. We get it from Standard Ceramics in PA, so if you would like them to narrow down which type it is you could always give them a call. Please let me know if you have any further questions.
Thanks
-Theresa
410-235-5998

This means that Clay Works Supplies, like many other clay suppliers on the east coast who buy from Standard Ceramics, is selling Bayferrox 130 as "crocus martis". Most suppliers on the west coast seem to spread out from New Mexico Clay, selling Bayferrox 180 as "crocus martis".

It will be interesting to see how Bayferrox 180, very pure with a very small particle size compares with a less pure Bayferrox 130, 94.2% with 1% LOI with a much larger particle size.

If a large particle size helps, Bayferrox 503 combines 98.1% pure with 1.3% LOI, with an even larger particle size.  But I'll have to find a supplier who sells it, as it doesn't seem to be a product in the USA Lanxess line-up for cement contractors.

http://bayferrox.com/fileadmin/pdf/IPG/56190590_000_BF-503-ENG.pdf

Comment by Jeff Poulter on May 12, 2013 at 2:35pm

If I had been thinking, I would have mixed up some Magruders & Touchstone as well. Oh well, there's always next Saturday!  jhp

Comment by Jeff Poulter on May 12, 2013 at 1:41pm

So, as I write this, the kiln is cooling down.  Besides the couple of pots in there, there are also some test shards.  I mixed up the Penland Red-Orange using the crocus martis from NMC.  I also mixed up Orange Street using the Special RIO & the crocus martis from NMC.  While I was at it I mixed up a slightly different version of C Harris Tenmoku using the Special RIO as well.  They are all 3 on porcelain shards as well as Red Calico shards.  Will post pics tomorrow.  jhp

Comment by Norm Stuart on May 10, 2013 at 6:43pm

Nadine,

The glaze turns out pretty similar regardless of what slow-cooling I do or don't use.  Next time I'll use Bayferrox 180 for the Red Iron Oxide, which New Mexico Clay sells as "crocus martis". I replaced crocus martis in the original recipe with the yellow iron oxide.

136.5%     ORANGE STREET  ^6
 46.8%      Feldspar - Minspar Kona F4 Soda
 17.9%      Gerstly Borate
 15.2%      Silica
 13.8%      Talc
 12.0%      Bone Ash
 8.1%        Dolomite
 4.5%        Kaolin
 12.0%      Red Iron Oxide precipitate
 6.2%        Yellow Iron Oxide

Red Iron Oxide precipitate - Bayferrox 140 . . . http://www.standardceramic.com/Materials.html

or try Bayferrox 180 . . . http://www.nmclay.com/Amazing/itemdesc.asp?ic=CROCUSMARTIS&eq=&...

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