New Mexico Clay

2011-12-09T16:24:00.000-07:00

New Mexico Clay’s Cone 10 Bodies
for General use in reduction, wood or soda firing.

ANN’S (NEW) SODA AND WOOD FIRED WHITE STONEWARE: Our Cone 10 soda and flashing body contains 2 Kaolins (Helmers is one) for whiteness, and stoneware and sagger clays for flashing, also has 10% fine grog. A creamy color in oxidation, a grey color in light reduction. Flashes rust in soda.

Throwing notes: “Throws great for tall thin pieces, not a “tight” body” “Throws Like a dream!”

SOL: All California fireclays give this versatile clay body a pleasing sunny California toasty warm color in reduction. Our sand doesn’t pop out giving the body a smooth texture after firing.

Throwing notes: “Another great body for tall thin pieces, moves easily. ”

Rev:12/09/2011

HIGH HILLS II: Our version of the popular Missouri fireclay, Goldart, ball clay and grog type stoneware. Very forgiving and throwable clay for production potteries. Tan to gray brown in reduction, medium texture. Jeff Zamik approved ZAM body.

Throwing notes: “It is a “tight” body (it resists your effort to move it). Stands well on its own. Great for wide bowls.

New Mexico Clay 3300 Girard NE Albuquerque
New Mexico 87107 USA
Fax 505-881-6067
800-781-2529

www.nmclay.com

More Materials bite the dust!

2011-09-14T17:21:00.000-06:00

No more PV clay. Plastic Vitrox was mined in California, but lack of demand and quality control have doomed the material.

No More Cornwall stone, we have been selling the substitute but its not the same.

Kona F4 now use Minex (good sub!)

White Talc the talc is now charcoal grey.

G200 is being blended by laguna so we still have it available.

2011-07-07T12:02:00.000-06:00

Recently New Mexico Clay Customers had a problem with a clay body (High Hills) we have been making for 14 years.

HIGH HILLS is our version of the popular Missouri fireclay goldart ball clay and grog type stoneware. It is a very forgiving and throwable clay for production potteries. Tan to gray-brown in reduction, medium texture.

Cone 10 Shrinkage: 14% Absorption: 0.1% Penetrometers: 7

We previously had to fix a problem with iron or manganese spots caused by the fire clay Hawthorn 35. This clay is used by various companies to make refractories, cement kilns and other industrial processes. Only 1% is used to make clay for potters. The spots were caused by the fact that the fire clay was unscreened. The purpose of a fire clay in a clay body is to provide tooth or texture.

We are now using a screened (40 mesh) Hawthorn.

The new problem mainly effected people who fire in gas kilns and do a heavy body reduction. These Potters experienced shivering and dunting; probably caused by a change in the chemistry of the fireclay.

The samples the potters brought in showed signs of Black Coring caused by over reducing iron; changing red Iron oxide to black iron oxide or worse-iron silicate. Large amounts of coal and other organics in the clays can exacerbate black coring, so I checked the raw materials for excessive Loss on Ignition.

Everything seemed perfect no problems, L.O.I. was lower than expected for all the clays.

Test of raw clays in High Hills
	Initial weight	Dry*	loss	Fired#	LOI	color
OH #5	294	293.1	0.31%	265.5	9.4%	creamy white
Goldart	294	290	1.36%	263	9.3%	creamy white
OM4	294	291	1.02%	263.4	9.5%	creamy white
Hawthorn 40	294	288.5	1.87%	257.3	10.8%	peach
	grams
	*Bake at 350F for 4 hours
	#Bake at 1000C hold 1 hour 1832F

Large amounts of iron also cause black coring but as you can tell from the clay descriptions this is a light colored clay body.

James Jarrett of Imerys (A Giant Clay Company) took pity on our plight and ran some tests on all the ingredients and the finished clay body.

				New Mexico Clay
				2011-19


Sample id			OM #4	Goldart	# 5	Hawthorn	High Hills
			K-T Clay		OHCC	Fireclay	C 10
						40 mesh	12/29/10
	Received		05/31/11	05/31/11	05/31/11	05/31/11	05/31/11
Chemical
	Si₂O₃	%	59.3	56.0	59.1	54.1	57.7
	Al₂O₃		27.8	29.8	27.7	31.2	29.3
	Fe₂O₃		1.19	1.26	0.83	1.93	1.64
	TiO₂		1.81	1.46	2.25	1.37	1.34
	CaO		0.14	0.37	0.12	0.32	0.33
	MgO		0.19	0.49	0.13	0.30	0.33
	K₂O		0.45	1.44	0.52	0.96	1.15
	Na₂O		0.11	0.11	0.11	0.11	0.11
	L.O.I.		9.2	9.9	9.2	10.5	8.2
	Carbon		0.186	0.102	0.057	0.048	0.085

This showed nothing wrong.

High Hills clay Reduced
in Miya Pottery’s Giel kiln at 7000’

Same piece on edge Note the Obvious black core.

EDGE Glaze Air

Nothing wrong… So I called a ceramic engineer, Jeff Zamek.

Jeff agreed to try to figure out the problem, he studied the formula and interviewed the people who had problems.

He suggested a few changes in the clay body; we have made these changes and now call the clay High Hills II

My conclusion is that having too much fireclay in the formula coupled with long reducing firing allowed for excessive Cristobalite production. Cristobalite changes its shape around 200°C (392°F). This can cause dunting and shivering.

Some of these steps can help. (this from Laguna Clay)

1. Fire slowly enough 1290° to 1650° F to give the carbon and sulfur in the body time to combine with oxygen and work its way out of the clay body. The burnout process must be done slowly and completely before the glaze begins to melt. In oxidizing atmosphere!2. Provide an oxygen rich atmosphere. In electric kilns, use plenty of ventilation in the bisque fire. If your kilns are densely loaded, use a downdraft kiln vent. In gas kilns, keep the kiln in oxidation from 1290° to 1650° F.
3. When using iron-bearing clay bodies, fire up to 2100° F in complete oxidation to allow for proper and complete burn-out of the organics; then, if desired, begin the reduction process.

Further reading:

Putting the Fire in Clay by Jeff Zamek
http://www.ceramicindustry.com/Articles/Feature_Article/BNP_GUID_9-5-2006_A_10000000000000159771

How to Solve the Problems of Body Cracking and Glaze Popping in Stoneware Bodies by Maynard P. Bauleke see..
http://www.kgs.ku.edu/Publications/Bulletins/211_4/bauleke.html

2011-06-20T10:02:00.000-06:00

Annual Empty Bowls 2011

Abuquerque Empty Bowls

Albuquerque Empty Bowls will be held Sunday, September 25, 2011, 11:00 am - 2:00 pm at Project Share, 1515 Yale Blvd. NE

Donations of pottery may be delivered to: NM Clay, 3300 Girard NE, Albuquerque.
Deadline for donations: Saturday, September 17, 2011
Pottery Throwing parties will be held in June and July - schedule to be announced.
Contact: Michael Thornton 344-4644 thesaurusstudio @ aol.com (Remove spaces)

The first throwing party is...

NM Clay:

June 25 Throwing Party 10-2pm Sat

July 23 THrowing Party 10-2pm Sat

Waxing Friday Aug 19th 10-2pm

Glazing Saturday August 20st 10-2pm

New York Steak Kiln Cooking Roast for Christmas 2010!

2010-12-13T15:12:00.002-07:00

Kiln Cooking a roast in Skutt kilns is exactly the same as cooking it in oven at home. Purchase a whole New York state roast in a cryovac bag. Preheat Cooking kiln to 350 degrees. Rinse the roast and then dry, in the photo above I have been cut in half so it would fit in the pan and cook faster. Season the roast with salt and pepper and perhaps a little garlic, roast in kiln at 350 degrees until it registers 125 degrees on instant read meat thermometer. Let rest for fifteen to 20 minutes. Degrease the pan juices, and serve on the side. because the heat in the cooking kiln comes from all around the roast the juices in the cooking pot do not boil, so they don't splatter.

It is not necessary to start the food at a higher temp to brown it. The side elements in the kiln act as an rotisserie and brown the food evenly.

Disclaimer: Both Skutt Kilns and Paragon Kilns would tell you not to try this. Especially if you fire a lot of lead based glazes. However I am sure my kiln is cleaner than your oven, really go look!

Download the Skutt Kilns Kilnmaster Manual click here (pdf)

2010-06-23T16:59:00.002-06:00

Pottery-Classes

Classes Starting July 5th

Learn Pottery techniques with experienced teachers. Express your creativity with therapeutic qualities of clay. Try the potter's wheel or make great functional hand built pottery in a community atmosphere right here at New Mexico Clay. It is fun and educational for Adults and Children.

Changes in the feldspar scene!

2010-02-10T16:23:00.006-07:00

Soda Feldspar - Kona F4
There is a supply change in the Soda Feldspar Kona F4. It is not available from the mine any longer due to a fire and mine closure. We will have Minspar 200 available. They are both very close to the F4 in composition. A chemical analysis of the materials is below. (Download data sheet)

Minspar 200 Feldspar	Kona F-4 Feldspar Sodium Feldspar
CaO 1.50	CaO 1.70
~~~	MgO 0.05
K2O 4.10	K2O 4.80
Na2O 6.50	Na2O 6.90
Al2O3 18.50	Al2O3 19.60
SiO2 68.60	SiO2 66.80
Fe2O3 0.06	Fe2O3 0.04
Volatiles % LOI 0.30	Volatiles % LOI 0.20

Minspar 200 was Formerly NC-4 Feldspar.

G200 update From Jeff Zamek Article from Ceramics Technical (November 1, 2009) (download G200 HD data sheet)

“G-200 felspar, mined by Imerys North America Ceramics, has been discontinued. While there are still stocks in potters' studios and ceramics supply bins it will eventually join Albany Slip, Gerstley borate, Kingman felspar, Oxford felspar, and other materials that have gone out of production. G-200's demise is based on economic considerations that potters do not control. Originally, G-200, as potters know it, was blended at the processing plant by using 70% Minspar 200, a sodium based felspar, and 30% HP G-200, a potassium based felspar. The blended felspars then became G-200 and were shipped throughout the United States.
The increasing costs of shipping Minspar 200 from Spruce Pine, NC and G-200 HP, mined in Siloam, GA, to the processing plant in Monticello, GA, a trip of over 200 miles, made this situation uneconomical. Potters are now faced with either using Custer feldspar in place of or finding a new potassium based felspar.”

Thank you Mr. Zamek I couldn’t have said it better or at all!

Laguna Clay will be blending G-200 so it will be available. G-200HP is the new product and according to Jon Pacini from Laguna the major difference is slightly more fluxing power, similar to (the also defunct) Kingman Feldspar of old.

Got the lead out, now what do i do?

2010-01-13T17:17:00.003-07:00

Wow the complaints and panic are coming in daily!

Duncan, Mayco, Gare and Amaco all got the toxic (but loveable) heavy-metal LEAD out of their products. Why? Most people using the glazes didn't know about the lead. Let's put that behind us and see what we can do today to get back to work.

We tested every low-fire clear glaze we could find and after much testing I decided they are equally okay. The problem is that of application, the old glazes you could slap them on and they looked great! Now not so much..

THE RULES!

1. Bisque low fire clays to Cone 04, either leave the kiln lid ajar until 800 degrees F or use a vent system. . This is very important as you must burn the carbon out of the clay during the bisque firing so it will not affect the glaze on the glaze firing. Carbon trapped inside the clay comes out as ugly blisters in the glaze on the second firing. Take at least 6 hours for the kiln to fire, faster firing is uneven firing and it takes time for the carbon to burn off.

2. Thin your glaze, mix well and keep mixing as you use it. Use a good brush!!! Apply two even, thin coats. Non-toxic glaze is much less forgiving to application errors.

3. Glaze fire to Cone 06.
Problems like crazing (crackled glaze) and shivering (glaze falls off pot on cooling) are easily avoided. Follow the RULES! We cannot re-create shivering on our clay bodies unless we bisque to Cone 4 (not 04). Crazing is caused by way underfiring, say to Cone 08 bisque and glaze.

Red Clay is a problem, the lead glazes of the past wetted the clay (as if you got it wet) and this gave us the bright colors we loved. Now we have a tradeoff between a durable glaze (IN1001) and a less durable or softer glaze that gives a little brighter colors. (Mayco's S2100)

Another new problem is that the Talc mine in New York was shut down. All the glaze companies made their traditional underglazes out of this lovely white talc. The only mine left is in Texas and the talc is a dark grey color. All the big companies had to reformulate the clay bodies and underglazes at the same time as we were getting the (forgiving) lead out. Be careful about putting opaque underglazes on bisque without testing. New Mexico Clay has used the Texas Talc for 25 years and so don't have the re-formulating problems.

2010-01-01T16:53:00.002-07:00

Well I haven’t tried the Copper Clay yet and I am at home, so I will say a few things about ......
Salad Dressing.
It is very important during the holiday season to make sure to eat enough salad, and having a good homemade dressing makes making a salad even easier.

This salad dressing is a cross between a traditional French vinaigrette and Caesar salad. Kind of. Don't be afraid of the ingredient list as many can be substituted.

In a clean, dry, mini food processer grind up a

1 clove garlic.
1 teaspoon of chopped onion or schallot.

(then add everything except the oil.)

2 anchovy fillets (just do it!)

2 dashes of Tobasco

2 dashes of Worcestershire

1 heaping teaspoon of Mayonnaise

1 teaspoon of Dijon Mustard.

1 Teaspoon of salt (or more)

1/2 Teaspoon fresh ground pepper

1/4 Teaspoon thyme.

3 Tbs. white wine vinegar (Pinot Grigio is good)

Mix well

Add 3 Tbs. of neutral oil like Canola or Grapeseed

Mix well

Add 5 Tbs. of good green fruity Olive Oil.

Mix well.

Taste, if it seems sour add more Canola oil.

Pour into your favorite small Grey Poupon bottle and store in the fridge. Makes about 6 oz for less than one dollar.

Copper Clay?

2009-12-29T15:19:00.000-07:00

A new item from Art Clay World is Copper Clay. Somehow this new clay can be fired with a torch. You must qwench the fired piece RIGHT away or it oxidises. To remove the black oxide you must pickle it in a mild acid at 140F! More info click here

Well if it works it should be real easy to use and will save a lot of kiln time as the COPPRclay we have had for a while needs to be fired in a saggar filled with activated charcoal in a digital kiln.

I will make something and fire it tomorrow!

Coyote Glazes crystals in glaze

2009-12-29T13:09:00.000-07:00

I was just informed by a customer in Las Cruces NM that every time she went to use her glazes she had to screen them. Remaining in the screen was a cup full of what looked like clear crystals. I had never seen this so had no idea... She called over to Frank at Coyote Glazes and he explained that when it is very cold the gerstly borate creates crystals and they need to be put in the microwave and melted then put back in the glaze. Who ever heard of such a thing?