[Clayart] Why you don't tell a Norwegian a joke on Thursday*. Mold release, crash cooling.

[John Mcclure]

Vince,
Mizzou does shrink and expand depending on the temperature reached. The
change is permanent per the data sheet;
Permanent Linear Change
After 220°F (105°C)-0.1%
After 1500°F (815°C)
-0.2%
After 2000°F (1095°C)
-0.2%
After 2500°F (1370°C)
+0.9%
After 2900°F (1595°C)
+2.8%


On Sat, May 12, 2018 at 8:49 PM Vince Pitelka <vpitelka at dtccom.net> wrote:

> Hi Duff -
> In my experience Mizzou castable does not shrink at all, not even
> slightly.  For a quality castable refractory, it would pretty much defeat
> the whole purpose if it shrunk in drying or firing, wouldn't you say?
> - Vince
>
> Vince Pitelka
> Appalachian Center for Craft
> Tennessee Tech University
> vpitelka at dtccom.net
> sites.tntech.edu/wpitelka/
>
> -----Original Message-----
> From: Clayart [mailto:clayart-bounces at lists.clayartworld.com] On Behalf
> Of Douglas Fur
> Sent: Saturday, May 12, 2018 11:32 AM
> To: Clayart international pottery discussion forum <
> clayart at lists.clayartworld.com>
> Subject: [Clayart] Why you don't tell a Norwegian a joke on Thursday*.
> Mold release, crash cooling.
>
> One thing to consider when using castable  refractories is they shrink,
> slightly. This will put a squeeze on any inside form. For small holes a few
> layers of newsprint topped with plastic wrap around an inner core gives
> enough cushion that  the core can be slid out. For larger or   complex
> shapes a core needs to be made so that it can be disassembled and taken
> out.
> ""Concrete cracks at corners" is a truism to remember a radiused inside
> corner is preffered to a sharp angle.
> A folk tale at the University of Oregon reported that David Stannard was
> seen loading an Alpine kiln at midnight. He and his fired pots were gone
> when folks came back in the morning. Moderation in the ammount of gas used
> so that the heat produced stayed in the kiln and crash cooling with the
> blowers on were given as how he dun it.
>
> Duff
> Seola Creek
>
>
> *"because he'll laugh during the sermon."
> (or post comments after the topic is long gone)
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