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How to achieve geological finishes in electric kiln?


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Hi!

I'm trying to achieve geological textures in an electric kiln: super matte finishes and uneven crackling textures in earth tone colors and a burnt look .  

I've been  using magma and crawl glazes, but not getting the exact textures I want and often they turn out satin or shiny.

 I've attached 3 images of wood fired and gas fired pieces that look like what I"m going for.  Unfortunately I don't have access to wood or gas kilns, plus parts of my pieces use  cone 5 or 6 glossy glazes that need uniformity.  And my pieces  are large and weigh  100lbs+.   

I have an electric kiln and a  blow torch.     

any suggestions on how to achieve these textures in an electric kiln?   

If I can achieve the crackling texture in the greenware state, by using slip, I'm thinking maybe there are certain chemicals that can be sprayed on to achieve similar uneven matte, burnt effects?  

 

@Magnolia Mud Research 

 

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The pot was first made as a thrown cylinder that was about half the diameter of the final diameter.  A coating of dry kaolin or a nearly dry paste of kaolin was applied before the cylinder and then allow some time for the coating to dry somewhat. This could be by waiting for the surface to dry or by heating with a heat gun.  When the surface was "dry enough" for the surface to crack when the cylinder was spread to final dimensions. The pot was then bisqued.  The glazes was applied and then fired in a kiln.  This pot was in a gas reduction kiln to ~cone 10.  
If the pot were fired in a electric kiln the glaze would be different due to the lack of reduction and some moisture from the gas fire.  
some areas were coated with a shino glaze, some was coated with a spray of baking soda.  The project was to create a cracked surface.  

The choices of glaze and the ways of application can make the cracks stand out or almost disappear.  If my memory is correct, the glazed cracked areas was applied with a sponge.  the none glazed area was sprayed from a hand sprayer.  the top area and the faraway edge top area the cracked area in the image is a run of the interior glaze which was a celadon glaze. 


The cracked surface and the method of application of a glaze gives the potter a wide range of final appearances.  The method is great if you are willing to have each pot be different.  If you must always have the same look you will be wasting time and material.  

I chose kaolin because it was available; Crushed bisque ware, sand, and other materials will work.  I switched long ago from slips to dry or paste coatings as they always make cracks;   work with the old alka seltzer slogan "try it you'll like it" approach;  you learn more that way.  

LT
 

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texture pots with natural materials, expand from the inside when the clay is on the dried side and more prone to cracking a bit when stretched. use  groggy clay. make slips from red, brown, tan stonewares apply multiple layers. use ash glazes. sprinkle ashes and frits on  your glaze before it goes in the kiln, i've had luck applying thin coats of glaze with a spray booth to give a sheen to a piece but not make it seem like it was dipped in a bucket of glaze. you will have to work harder upfront to get an "interesting" surface like this in an electric kiln vs working harder during the firing with something wood fired. 

 

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Perhaps of marginal interest

 

Sodium silicate stretch ...

Using a Sodium Silicate Pottery Technique to Create Cracked Texture
https://ceramicartsnetwork.org/daily/article/Deliberate-Cracks-Heating-and-Stretching-to-Create-Crackled-Texture-on-Pottery

... with terra sig
https://clayartcenter.net/mica-terra-sigillata-product-guide/
MicaSig_Reference-Pots3-1024x1024.jpg

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