[Clayart] sawdust instead of straw in primitive kiln

L TURNER magnolia.mud.list at gmail.com
Mon Apr 4 20:16:48 UTC 2022


Robert:

I often coat the outer surface of mugs and bowls with a thick slip/paste
that will be porous after the glaze firing but the main interior surface
will be mature and with zero porosity; no leakage unless there is a crack.

there is another point to consider:  if the liquid is too hot to hold with
you fingers ,is it not too hot to drink without scalding your mouth and
throat?  As I remember that the white porcelain coffee mugs in the D
battery mess hall was easy on the hands and scalding on the mouth, but then
was a long time ago and this is the 21'st century where everything is
different.  (or is it?)

LT

On Mon, Apr 4, 2022 at 2:30 PM Robert Harris <robertgharris at gmail.com>
wrote:

> Yes, I've thrown double walled teapots and mugs, but frankly they're a bit
> too heavy to be useful (at least if they're going to contain more than a
> thimblefull!. At least in my opinion.
> Throwing two separate pieces would allow for more and easier trimming to
> really get the weight down, but doing so accurately enough to get a mug of
> reasonable outer dimensions, while containing a good amount of liquid would
> be tricky.
>
> I like LT's laminating idea though.
> Of course one could make something porous and underfired (which I think
> many Japanese teabowls are), but that leads to many of the same leakage
> problems that earthenware has.
>
> Slipcasting is the probably way to go. although I'm not sure how one could
> slipcast a double walled teapot - unless you did it in two halves and
> joined them.
>
> On Mon, 4 Apr 2022 at 05:25, David Woof <woofpots at hotmail.com> wrote:
>
> > Hi Ron, Everyone,
> > Also, with a bit of good clay, manual dexterity and finesse one can learn
> > to throw a double walled pot with insulating "dead air space" between at
> a
> > single throwing.
> >
> > Not a new idea, but often forgotten or disregarded as too difficult to
> > master in "precious" time one allows.
> > Not so!  Sit down..relax and by the second or third attempt "ya gets it"
> >
> > Misneach,
> >
> > Woof....who ain't afraid to try.........If at first you don't
> > Fricassee.......fry, fry a hen!!!
> >
> >
> *****************************************************************************
> > ________________________________
> > From: Clayart <clayart-bounces at lists.clayartworld.com> on behalf of
> > ronroy at ca.inter.net <ronroy at ca.inter.net>
> > Sent: Sunday, April 3, 2022 10:45 AM
> > To: Clayart international pottery discussion forum <
> > clayart at lists.clayartworld.com>; L TURNER <magnolia.mud.list at gmail.com>
> > Subject: Re: [Clayart] sawdust instead of straw in primitive kiln
> >
> > You can also put two pots together with an air space between. I've
> > seen this done with slip cast forms. I'm thinking, if ones repeatable
> > throwing skills are good, it could be done.
> >
> > Certainly would eliminate the need for handles.
> >
> > RR
> >
> >
> > Quoting L TURNER <magnolia.mud.list at gmail.com>:
> >
> > > Robert,
> > >
> > > (I fire at cone 10 gas reduction).
> > >
> > > I have been playing with laminated clay bodies.    using a standard
> cone
> > 10
> > > clay body and applying a mixture of kaolins only as a paste for the
> outer
> > > layer.  The outler layer fired to cone 10 is still absorbant (aka: has
> > fine
> > > holes in the kaolin layer).   so far, I have no problem with the
> > interface
> > > of the two layers.  For thrown ware, I apply the tacky (but not a slip)
> > > kaolin paste to the form near the final step of throwing.  On handbuilt
> > > ware the paste is added after the form is completed.
> > >
> > > If you were to use a similar layer between your inside surface clay
> body
> > > and your outside clay body, you might get the "insulation for hot
> drinks"
> > > you were looking for.
> > >
> > > If you are using a mid temperature clay body, then use a high fire
> course
> > > clay body for the middle layer, or just use the sawdust clay as a
> middle
> > > layer.
> > >
> > > LT
> > >
> > >
> > > On Sat, Apr 2, 2022 at 6:55 AM Robert Harris <robertgharris at gmail.com>
> > > wrote:
> > >
> > >> I've put sawdust in clay. Biggest problem is that it caused serious
> > >> pinholing in the glazes. Otherwise it fired just fine.
> > >> Obviously it depends how much you put in! (My aim was to produce a
> piece
> > >> with enough air gaps that it would provide insulation for hot drinks,
> > >> didn't really work).
> > >>
> > >> We also wad all of the posts in our kiln, even in a regular reduction
> > >> firing, and we use sawdust (about 25-30% by weight which is probably
> > >60%
> > >> by volume), makes the wadding just crumble right off.
> > >>
> > >> Not sure what your aim is, by adding sawdust.
> > >> The long fibers in paper help stabilise the clay, but sawdust won't
> > provide
> > >> that.
> > >>
> > >> On Fri, 1 Apr 2022 at 11:29, Carolyn Curran <cncpots2 at gmail.com>
> wrote:
> > >>
> > >> > My inarticulate bad.   Sorry I confused you.  I intended to add
> > sawdust
> > >> > IN  the clay body along with vermiculite or perlite and grog...sort
> > of a
> > >> > paper clay situation, since straw and sawdust both  have
> cellulose.  I
> > >> > would probably wet it so there won't be particles flying through
> air.
> > >> > With my  COPD and chronic bronchitis,  I  don't think I'd play with
> a
> > >> > sawdust firing, although we have a trash can with holes here that
> was
> > >> > probably used in that way.  (Heck,  I only use   non toxic iiquid
> > >> > combustibles  for any raku..have a bottle of
> > >> > high test  Everclear booze for the purpose, use sparingly at bottom
> of
> > >> > combustion chamber..  I have had great success with the alcohol with
> > >> small
> > >> > scale work in  old Aim test kiln with one vase almost 8" tall which
> > was
> > >> > super unique in  subtle coloration. It is still a  big favorite.
> > >>  Carolyn)
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> > Ron Roy
> > ronroy at ca.inter.net
> > Web page ronroy.net
> >
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