Potters & Sculptors - Making Rock from Mud
I am just starting to put my first order together for raw materials for cone 6. The online catalog at Aardvark lists 3 different Talcs: Talc C2773 (MB-92) $1.35#, Talc C88 (4388)$1.25#, and Talc C98 (2882)$1.25#. When reading the details link for each it is the exact same text.
Does anyone know which one I should order. Thanks
Additional info: the first choice is (27% Calcined / 73% raw).
When I do a Google search of C2773 I only get references to Aardvark's website, so that's a number that only means something to them.
When I search for Talc MB-92 I get references to Pioneer MB-92 Talc, so that's the manufacturers number. Each manufacturer number has a specific chemistry which Aardvark is not providing you. Unless they can tell you or you can find the manufacturers specs, you simply don't know.
Compare the scarce information from Aardvark to the information supplied by Laguna/Axner for the third product listed Pioneer 2882. http://www.axner.com/talc.aspx From the analysis of this dark grey talc, you can see that it loses 6% to 12% of its weight as gas in the kiln, primarily burning-off carbon. You can calcine talc yourself by firing it in a container to 600 F or so for 30 minutes - enough to oxygenate the entire batch, but there's usually no reason to do this.
Laguna/Axner also usually stocks better quality material, which are not listed, if you inquire.
Digitalfire lists three different types of talc. http://digitalfire.com/4sight/material/t.html
When comparing a ceramic material, the lower cost material definitely has one or more of these characteristics:
a.) has more iron or manganese contaminants so it burns less white;
b.) has more organic carbon contaminants so it will lose weight in the kiln gas. Talc with carbon is grey rather than white;
c.) is a coarser material (say 100 mesh) so it does not melt as uniformly as a finer ground material (say 350 mesh);
d.) some other undesirable characteristic.
Sometimes the more expensive material is more costly due to the freight cost of being brought from the other side of the world, but your supplier probably wouldn't stock this more costly material if it were not better quality.
You'll face this quality choice with Talc, Silica, Kaolin, Clay, Bentonite and perhaps a few other raw materials.
For our studio I buy cheap talc and adjust the quantity for the LOI lost as gas. But we purchase better quality clay, silica kaolin - and especially bentonite
There's a relatively new and inexpensive bentonite from China which some suppliers carry, Bentone-EW, which is even whiter-burning and has far more suspending ability than very costly brand name Vee-Gum bentonite. Someone told me Trinity Ceramics in Texas carries it. Hopefully other suppliers do as well.
Thank you Norm,
I appreciate your thorough answer. I will add these notes on Talc to my notebook.
I was checking out Aardvark because it is 50 miles from me and Laguna is about 90 miles. (Oceanside, CA) But I think when I am ready to order I will drive the extra miles and go to Laguna. For one thing I always liked their clays. I used the Aardvark Bee mix at school and I found it harder to throw. I found it difficult to work with Laguna's website because they don't give prices for raw materials. Aardvark has an online order form so I can see the prices for different quantity price breaks.
Thanks for your help.
The only reasonable way to deal with Laguna Clay is to use their Axner website to obtain volume pricing on each item. Laguna's California price will be arbitrarily higher or lower than the Florida Axner price, but not by much.
When you're ready, email your proposed order to firstname.lastname@example.org which goes to Julie Brooks and you'll receive a price quote back by email in the next day or two. For the first order you'll need to "set up an account" which consists of nothing more than providing your name, contact details, and form of payment.
You'll receive a 5% Will Call discount for picking the order up yourself. If you want to experience some brusque disinterest call Sales on the phone to place your order rather than faxing or emailing - for extra abuse ask for Christine. I wouldn't want to work there myself, so I understand why they prefer email.
You'll also receive a volume discount on all dry and wet clay. 500 pounds (10 boxes of 2 pugs each) will earn you a 21.6% discount, with a 25% discount on 1,000 pounds and more for very large orders. With an order of 1,000 pounds or more you can have your order delivered by their truck, on a mystery day of their choosing, for $30 (we're 35 miles away) and they'll also try to include a $6 pallet charge. We have a busy candle store next door so I always send the driver off with a couple of new pallets and they waive their $6 charge.
We get a truck delivery about once every six months and occasionally drive the 35 miles there ourselves for in between stuff we need. You definitely have to see it once in person yourself just to see the size of the warehouse and trucks.
Hi again Norm. the above post by you was very helpful. I went onto the Axner site and built a spreadsheet with all the materials I would need to get to make 5000 grams of each of the MC6G recipes. (I think it may have been you who shared a spreadsheet named "MC6G" that I used to make my own spreadsheets.) That was only about $300 so I tried to come up with larger amounts of materials that I would want to do more glaze tests. Could you and anyone look over the sheet and let me know if I am way off in my estimation of what I will need to start glaze testing.
Glaze room all set up waiting for kiln and supplies.
That's a pretty good list, and here's my suggestions for you:
1.) drop Darvan 7, as 811 will do all you need and Darvan has a shelf life problem after a couple of years;
2.) drop Iron Chromate because you'll probably never use it and can easily use iron oxide and chrome oxide;
3.) drop Yellow Ochre and add Yellow Iron Oxide;
4.) drop one of the two cobalts, coppers and nickels, we order cobalt oxide, nickel carbonate and copper carbonate;
5.) we have ulexite and have never used it;
6.) you'll be doing a lot of recipe adjustments if you don't purchase dolomite;
7.) if you want to make crawl glazes you need magnesium carbonate;
8.) you're buying sodium carbonate, and for the same reasons you should add potassium carbonate and boric acid. They're all soluble fluxes which is not ideal, but sometimes it's the only way to get the percentage flux you want.
9.) you have Custer and G200-HP potassium feldspar. You should add Minspar 200, which is the Soda Feldspar which replaced Kona and other soda spars long gone from the market, and consider buying OLD G200 instead of HP which is what recipes call for;
10.) consider adding Ferro Frit 3110 for crackle glazes and fluorine frits 3269 and 5301 for interesting effects;
11.) consider adding strontium carbonate (or barium carbonate) for glazes which shift copper to variegated blue colors, like Ikeda Blue;
12.) I'd buy Ilmenite rather than granular rutile. It's cheaper and for me looks the same at cone 6;
12.) I'd buy only synthetic Red Iron Oxide from US Pigment
13.) I am not at all happy with light ceramic rutile. We previously had Dark Rutile and I bought some again from US Pigment and will know tomorrow if this gets us the "rutile-like" behavior we were used to;
13.) be particular about bentonite. Bentone-EW from Trinity Ceramics or VeeGum are tremendously more suspending and whiter. If a recipe calls for more than 2% bentonite, they were using the cheap stuff so adjust accordingly;
14.) you'll use spodumene for many glazes but you'll find it a sad replacement for glazes like Weathered Bronze Green which call for Fine lithium carbonate. I prefer the fluxier and even finer lithium fluoride at triple the price;
15.) Mason Best Black is a good first choice. These stains are pretty expensive but if you're looking for a true red, yellow, orange or some particular shade of color, you'll seek them out;
16.) If you like blooming crystals, buy from Rabco Specs http://www.rabcospecks.com/ Most of these Cone 06 "color crystals" work at Cone 6 but bloom bigger - but a few lose color, but can't tell you which ones.
Thank you again Norm, you are so generous with your information. Is the synthetic Red Iron Oxide the one called "Iron Oxide-Red (High Purity)". Updating my list. Thank you for the great teaching.