Thursday, October 19, 2023

  HANDBUILDING - FALL, SEPTEMBER-OCTOBER 18, 2023

October 18, 2023
All of your works have been bisque fired. We were introduced to Surface Decoration last week with Underglazed. We used two strategies with this: newspaper resist and applicatio of tissue prints. The next stage will be to apply a clear glaze. For this class, we use Duncan Pure Brilliance which we fire to cone 05 (low fire).

We learned how to make underglazes by using a slip recipe with added colorants.


Strategies for Decorating the Surface of your Green ware using slips, underglazes and stamps

Slips and Stains

Hand built forms in clay include a mix of surface decoration which might include commercial underglazes, slips, stains and glazes. When considering colour and surface decoration, the word “slip” refers to a recipe based medium for a colorants. People working with clay commonly refer to slip and understand the word as a liquefied suspension of clay particles in water which occurs whenever one works with clay. There is also “slip-casting” which is also a recipe-based concept and used with molds.

Often handbuilt forms in clay include a mix of surface decoration which might include commercial underglazes, slips, stains and glazes (often just a clear glossy or matte). When considering colour and surface decoration, the word “slip” refers to a recipe based medium for a colorants. People working with clay commonly refer to slip and understand the word as a liquefied suspension of clay particles in water which occurs whenever one works with clay. There is also “slip-casting” which is also a recipe-based concept and used with molds.

Slips are applied to wet or soft leather-hard greenware. Slip used on bisque usually follows an engobe recipe. They can be washed away to create a weathered look.

 

Slips are applied to wet or soft leather-hard greenware. Slip used on bisque usually follows an engobe recipe. They can be washed away to create a weathered look.

 

Susan Feagin  (Cone 04-9)

Custer Feldspar  27
EP Kaolin 34
OM4 Ball Clay 20
Sikica  19
--------
Zircopax  5

Sunshine Cobb Base Slip
Cone 04-9
Kaolin  34
Ball Clay  20
Potash Feldspar  27
Flint-silica  19
Zircopax  8
Soda ash  0.25
Sodium Silicate  0.25
____________________

Robin Hopper: WHITE BASE
Cone 04-12
in Ceramic Spectrum):

Ball clay 75

Kaolin 10

Silica 10

Feldspar 5

 


Colorants are added to the slips. There are two categories 1) Minerals 2) Mason Stains.
 I. Common minerals: Rutile (tan); Cobalt carbonate (blue – 1-3%); Iron Oxide (red-up to 15%); Copper Carbonate (green – up to 10%); chrome (darker green 1-3%).
2. Mason stains: infinite

Replace Underglazes with Engobes on Bisque Ware
Engobe recipe R Hopper –

Raw Material

          Cone 04-3

          Cone 4-6

           Cone 6-10

Kaolin

20

15

15

Calcined Kaolin

10

20

35

Talc

25

10

5

Calcium Borate (or Frit 3110)

15

10

0

Nepheline Syenite

0

10

15

Silica

15

20

15

Borax

5

5

5

Zircopax

10

10

10

Total

 

 

 

 

Class Pictures are coming




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