Giving you a simple recipe isn't that easy. I was not making wootz but was trying to make large, first stage direct reduction pots, similar to the process described by Needham as in use in Shanxia, China in the 19th century.
First, I talked with potters. After numerous clay trials I gave up on potters as being particularly useless and began reading patents. I followed them back through 'patents reference by' until I arrived at formulas I understood. Then I moved forward in the patent search trying out new formulas and recipes. Once I had a reasonable handle on the technology. I was able to talk with Ceramic Enginners without them putting the phone down on me in disgust. They really are very, very knowledgeable people who don't suffer fools gladly. The phrase, 'You're not even wrong' is a fond memory.
As you can see but the pictures of my trial notes, I tried all sorts of patents and variants. Outside of very sophisticated ingredients and manufacturing methods I found four, basic starting points.
Tradtional clay graphites, like Berlin pots.
Prof. Vasily's bulat pot recipes amd my variants
My own shrinkage adjusted, clay graphite pots. And,
a TiO2/ clay, silicon-carbide recipe I based on a patent for 'Self healing' crucibles.
I tried a lot of different things. I tried powdered aluminium addition to create 'Exothermic, internal drying' of clay bodies. I tried borax addition to create 'self glazing' pots and colloidal silica additions to prevent graphite oxidation ( OK for low temps but at steel ranges the whole pot just went into solution ).
Almost all of the carbon/clay pots will work for standard uses. Flake graphite is what you need and that posed my biggest problem, because of where I am. I was forced to use graphite furnace charge , made from ground electric furnace eletrodes or substitute with graphetised coke. Those I made with good grade graphite flake worked fine but were uneconomical to make.
Shrinkage reduction pots.
I won't go into detail here but clays shrink when they are fired. They shrink at known rates. Kyanite expands as it converts to mullite. It converts at the same temperatures as clay contracts. Hence, you can add kyanite in amounts to ballance this shrinkage making your pots ( in theory) more easier to fire and less susceptible to thermal shock
Standard 'Berlin' crucible recipe
fire clay 40%
Powdered coke 25%
Grog 15% ( traditonally ground broken crucibles)
I took these % by weight
A 9kg bre would be 3600gm Fire clay, 1800 gm graphite, 2250 gm powdered coke, 1350 gm #200 grog.
My shrinkage adjusted Berlin
Fire or 'Ball' clay 22%
Prfessor Vasily's bulat pot recipe follows a 7.3,1 ( or 2) ratio
7 parts volume Flint clay ( I used chamotte or 'flint grog. This isn't a clay but a hard, fired material)
3 part fire clay
1-2 parts grahite.
This is quite a tricky brew to mold as my chamotte was a a bit coarse. It would probably do well in a rammed mold. If you could find a finer chamotte, this recipe would be worth a second look for small, round wootz pots.
I made a variant that was shrinkage adjusted and used a finer, flint grog. It was much finer in texture and really quite tough for 'one off' use.
firedc clay 25%
#200 flint grog 15%
A brew that was quite promising in A8 size, rammed pots.
This has a TiO2 addition to create a 'self repairing' crucible as per the patent. A similar patent included 5% metallic aluminium powder. Once made into a wet clay, the water/aluminium reaction is claimed to dry the pots from the inside and result in Al2O3 additions. I made about 9 variants of this and had to pack up my whole shop and move it before all the trials were done. I did several recipes with alumina additions, but both the alumina and the metallic aluminium didn't seem to make any positive difference to this basic TiO2 recipe. For the test pot , I replaced graphite with graphitized coke, simply because I couldn't afford more graphite. It handled a 2kg cast iron melt but did show scouring at the slag zone. It was also very thermally transparent ( probably because of a porous structure caused by the coke loss) and the iron melted in a record time for my setup. I would definitely try this one again with flake graphite in a rammed mold.
Fire Clay /ball clay 35%
Graphite/G coke 45%
silican Carbude #200 17%
I tried a lot of different 'washes' to try to prevent carbon loss during bisque firing. One turned out fine for high temp pots.
Sil. Carbide powder (fine) 164 gm
Kaolin 36 gm
TiO2 20 gm
Al2O3 20 gm
Silica flour 20 gm
Water to form slurry. Painted on bisque fired pots, dried and furnace fired under use to stoneware + temps. I did some with a anhydrous borax addition and these produced the nice, chocolate colour you fine on commercial Borosilicate i.e. clay graphite pots. Fine for non ferous but degraded badly at steel temps.
A simple borax glaze brew I developed for non ferrous pots,
2 heaped teasoons of Kaolin
1 teasoon anhydrous borax powder
4-5 teasoons silicon carbide powder ( 1200#)
I did make several non-graphite pots which worked well at low temps but grapite is the main 'ant-wetting' agent in clay pots that stops slag errosion at iron and steel temperatures.
I'll post a few picture of my notes so you can get some idea of the volume of trials I did between 2004 and 2008. In the end, I decided to bypass crucible refining and allotted to make a small, tilting open hearth furnace for the Basic process. These note are only a fraction of those made over the four years. It might be a quick read but it cost me a lot in time and resources when just putting food on the table was a struggle.