Dry Glazes, Slips, Terra Sigilatta and Engobes for Cone 6 - Recipes and Techniques

Note 8/32/2014 from George Lewter - added the words "Slips" and "Terra Sigilatta" to make this topic more inclusive of the non-melted materials applied over clay bodies. 

Due to the nature of the glaze, this is obviously NOT to be used for functional pieces (for those that are new to ceramics), only sculptural pieces and is best when lots of heavy texture / sprigging is used to accentuate the different levels or layers and therefore colours. Hope that makes sense.

These recipes and techniques come from an Australian ceramic artist by the name of Simone Fraser. I obtained these recipes whilst studying ceramics at college many years ago. Her website is well worth a visit to see some examples of how she still uses these engobes, dry glaze techniques today. www.simonefraser.com.au

 

 

 

Step One - Apply Engobe to leatherhard clay over texture and bisque fire to Cone 06. You can cover the entire tile or sponge back in places to reveal the clay body underneath, which gives you another variation (nice).

 Photo below is to give you an idea of the colour of the engobe after bisque firing. You can also add more oxide to each engobe than I have here. Up to you. Test, test, test. The engobes don't look like much when initially fired to Cone 06 but at Cone 6 with dry glazes etc over the top, they work their magic. Incidently, I have used these under glazes too.

 

Engobe Base Recipe

Eckalite                60

Silica                     20

Potash Feldspar  20

Bentonite               3

   Varations I have used

1. Iron Oxide 8%

2. Chrome 4%

3. Yellow Iron Ox 3% + Copper Carb 3%

4. Cobalt 1.5%

 

Step Two - After bisque firing the engobed tiles, I apply various oxides washes over engobes then sponge off/back in areas to ensure that the underlying engobe is also visible.

NOTE: In all of the tiles shown here I have used a 'Rutile' wash (resulting in red) and a 'Manganese' wash (resulting in metallic dark brown to black). You will notice that the wash is prominent in the deeper texture here but that is up to you. Also, other oxides work too. I also mix a small a small amount of frit or Gertsley Borate and a little EPK to my oxide washes.

Also, when I was taught this technique at college, we were only taught to use the engobe and dry glazes in combinations. I have found that adding the oxides washes just adds another dimension. Up to you. TEST.

 

Step Three - I then sponge on the 'Dry Glazes' so that they appear on the very surface. This allows the underlying engobe and oxide washes to show through. You will also want to leave some of the very surface free from dry glaze to enable the engobe to show in areas. Wipe back with a damp sponge in areas if you overdo the sponging on. I tend to overdo it.

There are endless possibilities with this dry glazing technique. They can be sponged on, brushed on and wiped back. I have not covered all the variations as they are endless. I find that it works well to use contrasting engobes/oxides under the glaze to achieve the best results.

 

Here are the 3 tiles again and how I did each one.

Tile One

This tile has the following;

  • Engobe with 4% Chrome added to the base. Painted covering the whole tile.
  • Rutile wash on the left and Manganese wash on the right and sponged back lightly in places to reveal some engobe.
  • Cobalt Dry Glaze (Base with 2% Cobalt) sponged over the very surface, making sure not to sponge in to deeper textured areas and leaving some areas of engobe still visible on the surface too (I probably overdid it a little here with the dry glaze).

Tile Two

This tile has the following;

  • Engobe with 1.5% Cobalt Carb added to the base. Painted covering the whole tile.
  • Rutile wash on the left and Manganese wash on the right and sponged back lightly in places to reveal engobe.
  • Moss Green/Brown Dry Glaze (Base with 3.5% Yellow Iron Ox plus 3% Copper Carb) sponged all over the very surface, making sure not to sponge in deeper textured areas and leaving some areas of engobe visible on the surface. Moss Green/Brown tends to be green where heavier and moss brown were lighter application is achieved.

 

Tile Three

This tile has the following;

  • Engobe with 8% Iron Ox added to the base. Painted covering the whole tile.
  • Rutile wash on the left and Manganese wash on the right and sponged back lightly in places to reveal some engobe.
  • Cobalt Dry Glaze (Base with 2% Cobalt) sponged over the very surface, making sure not to sponge in deeper textured areas and leaving some areas of engobe visible.

Dry Glaze Base Recipe

Eckalite 2                    23 (I think EPK would be a sub, as Eckalite is a Kaolin)

Soda Feldspar             16

Whiting (calc carb)     28

Molochite #200           23

Frit 4193                      8

 

Add; 2% Cobalt for Blue

         3.5% Yellow Iron Ox plus 3% Copper Carb for Moss Green / Brown

         6% Copper Carb for Apple Green (i did not have an example of that          

          variation above)

 

If you have any questions, please let me know and make sure to have a look at Simone Fraser's website.

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Anyone know what Molochite #200 is. Thanks

Molochite #200 is calcined china stone, nearly identical to a calcined kaolin like Glomax.

Thanks Norm, Glomax I have.

Hello! I just posted a comment and was asking for this dry glaze application technique. I would like to know if the dry glaze is just the dry powder and if it is applied onto the newly glazed surface, still wet. I am tryin to achieve some superposition effects on plates and therefore, I should apply the dry glaze also underneath...

Many regards from Argentina!!

In this instance the artist is applying engobes to wet clay. It appears to me that first layer of engobe is applied wet, followed by a sprinkling of dry powdered engobe or wet engobe then distressed with a sponge - either dry or wet.

An engobe has more clay content than a glaze but has less clay content than a colored slip, which is a clay slurry with added colorant such as an metal oxide or mason stain. Engobes are often similar to underglazes, but I think with the the intention of an engobe to be applied more thickly.

Typical engobe recipes would look something like this, with a different recipe for each firing temperature.

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 100% 100% 100%

Simone does interesting work.   http://www.simonefraser.com.au/home/

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