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Marcia Selsor

Member Since 16 May 2010
Offline Last Active Today, 11:26 PM

#65377 Alumina Mechanism

Posted by Marcia Selsor on 30 August 2014 - 11:19 AM

Another short answer:the ratio between the Alumina and the silica determine the texture of the glaze.
The ratio between the fluxes and the silica determine the melting point. --very brief description


#65364 Trouble With Dried Out Glaze

Posted by Marcia Selsor on 29 August 2014 - 10:40 PM

Take the stubborn particles and run them in a blender for a while and then try to sieve. You should be able to break it down again.

#65352 What Causes Smoke Patterns In A Foil Saggar?

Posted by Marcia Selsor on 29 August 2014 - 03:37 PM

Foil sag gars that I do are not fired in a smoky trash can. They are fired with the colorants, chemicals, combustibles inside the foil sealed around the pot. II fire them in a raku kiln.
Russel Fouts uses masking tape resist in his foil sag gars with combustibles sealed in foil. Wax burns off way too early to leave a result of resisting smoke.here is his article on smoke firing in an electric kiln.


#65255 Kudos To Marcia For Her Article In Sept/oct 14, Pottery Making

Posted by Marcia Selsor on 27 August 2014 - 07:22 PM

Thanks, Pres!
PC sent out a clip to members of the Obvara firing process from the new dvd about expanding the potential of a raku kiln.It is a good real time demo of the content of the article. The web link to others doing obvara are missing.
here they are:

Do I really sound like that?

Thanks again for the pat on the back.


#65222 Zalik Tile Process -You Tube "from Clay To Mosaics

Posted by Marcia Selsor on 27 August 2014 - 02:39 PM

Stephani shared this with me today on Facebook. This is an amazing process and still used in many Islamic countries today. There is a factory in Granada, Spain as well. I saw a lot of ancient buildings and mausoleums in Uzbekistan with these mosaics. Really a labor intensive process.


#65139 Building A Small Cantenary, Mortar Question

Posted by Marcia Selsor on 26 August 2014 - 03:12 PM

Read all about them (clinkers) in the Potters book by Leach. We solved it by eliminating cold secondary air by making a collar of firberfax around the tube of the oil burner and sealing the burner port.


#65138 Irregular Bowls

Posted by Marcia Selsor on 26 August 2014 - 03:09 PM

I love Ruthanne Tudball's looseness. Also Tony Clennell"s. I think they work fairly wet but don't molest it's freshness by over doing it. Ruthanne completes a teapot in one sitting without it leaving the wheel.


#65127 Building A Small Cantenary, Mortar Question

Posted by Marcia Selsor on 26 August 2014 - 01:47 PM

i used a mix if fire clay , sawdust and vermiculite at the time 1971 for filling between the bricks on the curve. ( excuse the little hippie chick image)
I built this kiln in update NY with old bricks from a boiler in the woods. Empire firebricks.and an outer layer of insulation bricks. there had been an urban myth of using aluminum foil between the bricks but it really did nothing. Turned pretty much to ash in a firing or two. I did cover the exterior with a thin coat of home made castable which I have posted here before.This was a cross draft catenary. I built a larger cross draft in Illinois for oil burners. Those burners were in an article in Studio Potter in 1973.I cast some ridged plastic lampshades in a block of castable for the burner ports. I built another kiln for burners on each side of the door in Montana.-no photo.

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#65009 Wheel Wobble. How Much Wobble Is A Real Wobble?

Posted by Marcia Selsor on 24 August 2014 - 10:53 AM

Unless the camera was moving, I held a paper next to the edge of the board. It was moving and not the shaft. I would go around the wheel and tighten everything possible. If the shaft is bent, you will nee to replace it. A machine shop should be able to make one for you. Or maybe whoever manufactured your wheel could replace it.



#64621 Harpers Kiln

Posted by Marcia Selsor on 17 August 2014 - 03:22 PM

Success also would depend on if the heads have a good wall even wall thickness. Is the kiln in the classroom? Is it vented?

How thick are the pieces and how long have they been drying?

A simple firing would be to turn the bottom circuit on low overnight with the lid propped open about an inch. Early in the morning and put the second circuit on low. 2 hours later turn it to medium. 2 hours later shut the lid and turn it on full blast. Then sit and wait until the cones goes down.



#63991 Monkey's Fist

Posted by Marcia Selsor on 06 August 2014 - 09:23 AM

Just model them. Punch pinholes out of site to reduce the thickness issue.


#63844 Anyone Know How This Is Made?

Posted by Marcia Selsor on 04 August 2014 - 01:05 PM

I think it is a pressed image with cuer de seco

which is a resist line with a dark oxide to keep the colors separated.

#63666 Top 20 Potters From Ceramics History

Posted by Marcia Selsor on 01 August 2014 - 02:15 PM

Chris, that book about the search for porcelain in Europe is calle The Arcanum. Great read. 


If you look at the first ceramics show at the Whitney Museum in NYC Six Sculptors

you have

Peter Voulkos, John Mason, Kenneth Price, Robert Arneson, David Gilhooly and Richard Shaw, 

In Ceramics History in the US 

Mary Chase Perry Stratton  Founder of Pewabic Pottery

Mary Louise maclaughlin's work at Rookwood Pottery

Adelaide Robineau (the Thousand Hour Vase) and Taxile Doat at the Women's University in St. Louis. She initiated the Syracuse Ceramics National in 1929 and founded Keramos magazine

  She invited Taxile Doat to come to the US from the Sevres Porcelain factory in Paris.

Margarite Wildenhein

Maija Grotell , teacher at Cranbrook and former Bauhaus artist

Patty Warashina 

Robert Sperry

Stephen DeStabler

Charles Binns (Father of Alfred University Ceramics)

Ted Randall

Tashiko Takeaezu

Byron Temple

Maria and Julio Martinez

Potter Dave , the slave potter who captured souls in the face jugs

George Ohr, the Mad Potter of Biloxi

Bernard Palissy, French

Josiah Wedgewood

A good reference book might be 100 years of American Ceramics by Garth Clark or the collection at the ASU research center in Tempe, Az.

#63632 Burkes Strong Celadon

Posted by Marcia Selsor on 31 July 2014 - 04:04 PM


I think Ty has something. 

Although Glenn Nelson's base for ^6 has 64% Custer Feldspar, no silica 18 whiting , 9 ball clay 5 talc. That is it.

Here are some  celedons I used in Reduction and one for ^6 Oxidation

They all have much more silica 

Celedon^6     Reduction

Whiting  18.5

Neph. Syn 25.8

EPKaolin 18.8

Silica 31.1

Gerstley Borate               4.6

Red Iron Oxide      1.5           


AACC Celedon Cone 6

Color: light to medium green Tested

Surface texture: glossy

Type of firing: Reduction Glaze type: Ca


Ingredients: Percent Batch

Flint                       31.00   1550

Nepheline Syenite 30.00   1500

Gerstley Borate 21.00       1050

EPK Kaolin     10.00          500

Whiting            8.00           400

Totals 100.00 % 5000 gm


Also add:

Iron Oxide 1.00 50



May use up to 3% Iron oxide to intensify color


Possible Health Hazards:

Flint: free silica-wear a NIOSH approved dust mask when handling dry material

This is one for Oxidation
Selsor Faux Celedon ^6 Oxidation

Whiting 18.5
Neph Syen 25.8
EPK 18.8
Silica            31.1
Gerstley B     4.6
Copper carb 0.3
Mason #6600 Black 0.02

#63614 Quality Of Firing In Short Kiln Vs Tall

Posted by Marcia Selsor on 31 July 2014 - 06:24 AM

Congratulations. I think you should go visit one. I am 65 and I have a big oval. I use 2 cinderblocks to stand on to load it. The 18" kiln seems low to me. You could raise that height by putting it on cinderblocks. Go to a show room and feel what it is like to put a shelf into it. You could probably adjust the height for comfort for your back. The firing should be fine. That is a good company.