search  current discussion  categories  techniques - misc 

homegrown kiln- to calcine or not to.... now primitive grog

updated sat 15 dec 07

 

Bill Merrill on thu 13 dec 07

Kiln -cultural antecedents???

If you don't fire grog to high enough temperature you will get cracks in =
the bisque ware that you may or may not see when the greenware is =
drying. If the "grog" is not vitrified it will absorb water from the =
clay and cause the cracking I speak of. Grog is an issue today as the =
grog or what is being called grog doesn't compare to the grog of 30 =
years ago. The best grog I ever used was "Pueblo" grog made by A>P> =
Green Company in Colorado. It was a m=E9lange of color and was most =
appropriate for stoneware. A company in Ohio makes a fairly good grog. =
The company is: Maryland refractory Co.,
277 Salisbury RD.'POB 267 Irondale, Ohio 43932

Bill billm@pcadmin.ctc.edu





-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Robert
Sent: Thursday, December 13, 2007 9:28 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Homegrown Kiln- To calcine or not to.... now Primitive Grog =
Kiln -cultural antecedents???

Upon seeing my latest test brick it is clear to me that for the
quality of brick I am after would require me to convert a significant
proportion of my kaolinite flint fire clay to grog or calcine. While
the brick has adequate structural strength to build a kiln there are, to
me, excessive shrinkage cracks at cone 11. I would be dealing with
crumblies and I'm certain the kiln life would be reduced substantially.
I'm relatively certain that prefiring my raw material to deal with the
shrinkage prior to casting would resolve the issue. However I don't
currently have a kiln to fire grog and am inclined to build the kiln as
is, accepting the shorter life cycle and processing the material with
pots for the next kiln. I am, however, seriously entertaining the idea
of building a temporary kiln for firing grog. Cardew mentions the
necessity, in a pioneer situation, of building a temporary kiln for this
purpose and also "roasting" kaolin for the same. Does any one have any
reference to a simple method of burning grog say to 1800F or 2000F? Are
there any cultural traditions (pre-indusrial) where this has been
practiced? Could I just mix in an appropriate amount of coal/charcoal
and light the heap? The material is already at grog size, 1/4" to fines
so there will be no post firing crushing involved and the material has
certain limitations/requirements for containment in a firing. Thanks
for any input.
Robert
P.S. I know I could just go buy grog, but I have a longterm personal
commitment to utilizing local resources. Having access to this
material is one of the most unique situations I've had on that path. I
am committed to learning to use this material in the simplest way
possible with the long term vision of localized industry and in
particular several of the blacksmiths, glassworkers and potters that I
know in the area.
It's quite a thing to be able to borrow a pickup and drive up the
mountain and haul off your kiln, batch furnace, forge, smelting =
furnace.....
Take care

_________________________________________________________________________=
_____
Clayart members may send postings to: clayart@lsv.ceramics.org

You may look at the archives for the list, post messages, or change your
subscription settings here: http://www.acers.org/cic/clayart/

Moderator of the list is Mel Jacobson who may be reached at =
melpots2@visi.com

Duff bogen on fri 14 dec 07

Kiln -cultural antecedents???

Robert

Parts by volume- 4 perlite:2silica sand:1portland cement:1fireclay
cast ring bricks with a diameter of 30-36" throw some flower pots or slab build saggars. At the bottom make a firebox, corbel over with bricks stack grog in cylinders cover the top with shards busted bricks chunks of flint clay... build a fire (wood, fuel oil, sawdust,a touch of kerosene, a pinch of white gas{har}) and get it as hot as you can.
Duff
Does any one have any
reference to a simple method of burning grog say to 1800F or 2000F? Are
there any cultural traditions (pre-indusrial) where this has been
practiced? Could I just mix in an appropriate amount of coal/charcoal
and light the heap? The material is already at grog size, 1/4" to fines
so there will be no post firing crushing involved and the material has
certain limitations/requirements for containment in a firing. Thanks
for any input.
Robert
longterm personalcommitment

______________________________________________________________________________
Clayart members may send postings to: clayart@lsv.ceramics.org

You may look at the archives for the list, post messages, or change your
subscription settings here: http://www.acers.org/cic/clayart/

Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com




---------------------------------
Never miss a thing. Make Yahoo your homepage.