[Clayart] sawdust instead of straw in primitive kiln

Robert Harris robertgharris at gmail.com
Mon Apr 4 22:06:10 UTC 2022


Paul, at first I thought I completely agreed with you.

And then I realized you hadn't really thought through what you were saying.

If you think about the vacuum flask, it was first made from mirrored glass,
then more recently steel. And both of those are even worse at reducing heat
transfer than ceramic. (Especially when we consider earthenware).

Now whether it's worthwhile for an anachronistic maker of handmade potter
to do it is another matter. Material is a poor argument however. And since
we are anachronisms (from an efficiency point of view), why the hell not
try?

A friend of mine just sent me a picture of a commercial, slipcast, double
walled mug that he bought his wife recently. No handle necessary for piping
hot coffee. So it's obviously neither difficult nor cost prohibitive.
(Obviously the interior was conical to provide easy release from the mold,
so there will be limitations to shape).

Robert

On Mon, 4 Apr 2022 at 13:30, paul gerhold <gerholdclay at gmail.com> wrote:

> Too much effort in an attempt to make clay do something it really isn't
> ever going to be good at. Clay can make a great coffee or tea mug but it
> isn't ever going to be the best material for reducing heat transfer.
>
> Paul
>
> Sent from my iPad
>
> > On Apr 4, 2022, at 7:26 AM, 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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