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Scaling Down Terra Sig


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#1 2ndWind

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Posted 26 July 2014 - 03:22 PM

Greetings, I am attempting my first batch of terra sig and was planning to use the Charlie & Linda Riggs recipe:

 

28 lb or 3½ gallons (16 liters) water

 

15 lb (6.8 kg) XX Saggar Clay 
or OM4 Ball Clay

 

1½ tablespoons Sodium Silicate

 

1½ tablespoons Soda Ash

 

I have 2 lbs of OM 4 and a bottle of sodium silicate on hand, as well as the soda ash.  My question is how to scale down the recipe.  On a side note, I don't really understand the difference between Sodium Silicate, or the Darvons, or I might have purchased Darvon 7 instead because I notice the common recipes call for smaller batches.  Would I be better served either ordering more OM 4, or Darvon, or both?



#2 Chris Campbell

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Posted 26 July 2014 - 04:00 PM

Oh my goodness! That is an industrial size recipe!
You can find many recipes that are smaller.

This is from the Ceramic Arts Daily link at the top left of this page ...

http://ceramicartsda...hoot-terra-sig/

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#3 Marcia Selsor

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Posted 26 July 2014 - 06:50 PM

Here is a way and fast way to make #simple Terra Sigillata:

                        Fill a plastic liter bottle with 3/4 full of water. Add 100 grams of ball clay and a couple drops of Darvon 7, or Darvon 811 or sodium silicate. Add more water until the bottle is almost full. Put the top on tight and shake well. Let the mix set for an hour or so..until you see three separate areas of the mix. Clear, light and dark. If the top layer is completely clear, add more Darvon. You want some color in the top layer. Punch a hole at the bottom of the middle layer and let it squirt into a bucket.  Wait  until your piece is bone dry and apply to the piece with a soft brush. Burnish after each application. I use a soft sponge for burnishing. You can apply several coats as until it is shiny. Too much Terra sig can lead to peeling or cracking. Bisque to Cone 09 or 1670 F or 901 C



#4 alabama

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Posted 28 July 2014 - 11:55 AM

In 1990 I had an interest in terra sigellata and was interested in testing different soils around the state.

The method I was taught was to take a tall glass or plastic cylinder and fill it 1/2 to 3/4 of dirt and fill to the top with water.

Take about 2 cups of wood ash, put in a coffee filter, and pour 1 cup of water thru the ash.... the liquid will take the

appearence on apple juice.  This is the deflocculant.. 

 

Shake the bottle of dirt up, pour in two tablespoons to 1/4 deflocculant and allow to stand for 48 hours to 72 hours.

Pour off the clear water and gently scoop off the top layer of pigment and throw the rest away.  The sample will

separate into several stratified layers with the course sand being on the bottom and the terra sigellata pigment on top.

It all depends on the sample of how much pigment will be on top.... in a 20 inch cylinder, you might get

1/4 inch or a little more in pigment. 

 

If your pigment flakes, it means that the clays are shrinking at different rates, so add a little of the clay body into

the pigment to solve that problem.

 

Hope this helps,

Alabama



#5 Babs

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Posted 28 July 2014 - 07:49 PM

Here is a way and fast way to make #simple Terra Sigillata:

                        Fill a plastic liter bottle with 3/4 full of water. Add 100 grams of ball clay and a couple drops of Darvon 7, or Darvon 811 or sodium silicate. Add more water until the bottle is almost full. Put the top on tight and shake well. Let the mix set for an hour or so..until you see three separate areas of the mix. Clear, light and dark. If the top layer is completely clear, add more Darvon. You want some color in the top layer. Punch a hole at the bottom of the middle layer and let it squirt into a bucket.  Wait  until your piece is bone dry and apply to the piece with a soft brush. Burnish after each application. I use a soft sponge for burnishing. You can apply several coats as until it is shiny. Too much Terra sig can lead to peeling or cracking. Bisque to Cone 09 or 1670 F or 901 C

Marcia, To clarify, as I have read that it is the top layer only that you use, and I have read that it is the middle layer only that you use, from what yo have written you are keeping to use as ter.sig. the upper two layers?



#6 Marcia Selsor

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Posted 16 August 2014 - 08:22 AM

Babs,

My new dvd clip on Ceramic Arts Daily show how to make terra sig by smaller batches.

http://ceramicartsda...-the-raku-kiln/

 

by using the Darvon the two upper layers remain as one. I just don't use the heavy bottom section.

 

 

Marcia



#7 Marc McMillan

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Posted 17 August 2014 - 04:02 PM

great video, Marcia. Well done. 

That's an interesting technique for applying feathers and horsehair.

Marc



#8 Marcia Selsor

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Posted 24 August 2014 - 05:48 PM

The rest of the video, another 50 minutes covers alternative firing methods.

 

marcia



#9 Harold Roberts

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Posted 04 October 2014 - 10:36 AM

Thats a great method Marcia. I used to use goldart instead of ball clay. It was a warm white and a beautiful suface.






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