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Member Since 28 Apr 2013
Offline Last Active Today, 07:12 PM

Posts I've Made

In Topic: What Is Terracotta, Really?

25 November 2015 - 09:48 AM

... and this has just added to my impression that terracotta is pretty much whatever you want it to be


And -- even more confusingly - sometimes the term is used based more on the nature of the object made

(rather than the body used or firing temperature).

In archaeology and art history, "terracotta" is often used to describe objects such as figurines not made on a potter's wheel.

Vessels and other objects that are or might be made on a wheel from the same material are called earthenware pottery; the

choice of term depends on the type of object rather than the material or firing technique.[6] Unglazed pieces, and those made

for building construction and industry, are also more likely to be referred to as terracotta, whereas tableware and other vessels

are called earthenware (though sometimes terracotta if unglazed), or by a more precise term such as faience.

... from https://en.wikipedia...wiki/Terracotta


Looking for clarity I consulted Architectural Ceramics, David Hamiltion.

The terms 'terracotta' and 'faience' are generally understood to mean, respectively, unglazed and

glazed earthenware. Contrary to the commonly held belief, 'terracotta' does not only refer to red-

firing unglazed clay but may be applied to any unglazed clay.


At least one factory creates a terminological dilemma by calling all hand-pressed facings, whether

glazed or unglazed, 'terracotta', and all cast or mechanically made pieces 'faience'.



Go figure?


PS The traditional Spanish ‘botijo’ seems to come in all sorts of colours. In my very limited experience 

they are made with quite thick walls, which I assume is a functional decision.


... this page includes an experiment keeping water cool in an oven, and a ref to an old technical paper.

After 7 hours in an oven at 39C the water inside the cooler was at 24C. Wow!


In Topic: Cut, Spiral Bit Warped In Kiln

19 November 2015 - 04:10 PM

I'd been wondering about a variant of Chris's idea. Fire fully-cut and unglazed to cone 6

with the pot resting on its rim. Looking at the first picture most of the slumping seems to

be happening near the rim. (At the least you are reducing the spiral by its thickest 1800.)


Then low-fire glaze.  BTW glazing a vitrified pot can present problems, unless you are

using a "painting" glaze full of gums.

In Topic: Tin Can Raku Glaze

19 November 2015 - 04:42 AM

A google for raku glaze "tin-can" brings up several recipes


In http://general.utpb....aku-texture.htm

Tin Can Matt Rainbow

Gerstly Borate 4 Neph. Sy 3 Copper Carb 1 Black Nickle ¼



In http://members.chell...ku-glazuren.htm

Glaze name: Tin Can

Firing: Raku
Color: metallic patina
Date: 05/13/98

Recipe: (Percent, Batch)

Gerstley borate            48.48        4.00

Nepheline syenite          36.36        3.00

Copper carbonate           12.12        1.00

Black nickel oxide          3.03        0.25

                        --------    --------

Totals:                   100.00        8.25


Recipe in parts by volume.

From Piepenburg's book "Raku Pottery".  Should be the consistency of very thin milk.

In Topic: Can't Rub Anything But India Ink Into Cone 5 Clear Crackle Glaze

15 November 2015 - 03:33 PM

You may find an old thread of interest


In Topic: Kiln Controller

15 November 2015 - 09:17 AM

Purely web browsing...


In the UK Potterycrafts advertise the ST315, but in the associated video the controller is clearly marked ST315A


It looks like the manufacturer's web site is at http://staffordinstruments.co.uk/

and I cannot find any references to a ST315B on it. Although it does mention cable options.


The web page for the ST315A seems to be http://staffordinstr...ure-controller/

and it contains downloads for the Datasheet, User Manual and Installation Instructions. You might want to look at the bottom RH

corner of p3 of the Installation Instructions, as it mentions a a yellow warning label which the indicates factory configuration options.


BTW a ST315B is advertised here, but I didn't notice any differences mentioned.



I have seen pictures where the case clearly shows ST315, and others where it shows ST315A. Does yours show 315B?