Lava texture

[Giotto]

Hello - I have been researching a technique to get really rough texture, like with stuff coming out of the clay, that is often achieved by wedging in granular feldspar, which melts out during the firing.  I am very interested in very rough surfaces (lava like) in the clay itself prior to glazing.  I heard of people wedging in certain ground stones.  If you have specifics in using the granular feldspar or any other ground stone (amount used per pound of clay, and what firing temp) I would be so very grateful.  I typically bisque at 04 and fire to cone 6, but am also interested in doing single firings, as I will not be glazing but just using stained slips.

Any information you can provide or a direction you can point me to will be invaluable:)

Thank you in advance.

[JohnnyK]

You might take a look in the CAN store for Additions to Clay Bodies for info along the lines you are searching...

[Kelly in AK]

This might not be exactly what you’re looking for, but I figure it can’t hurt. Long ago I did several hand built pieces with clay that had coarse sawdust wedged in. I did it by feel, not measurement. I wedged in as much I could and still keep some plasticity.  I can’t remember even vaguely the percentage. It gave me a beautiful texture and I made the work really thick. The pieces were fired to 04, but the idea came from trying to make my own softbrick. I made a lot of those, which fired to cone 10 just fine. 

[Magnolia Mud Research]

22 hours ago, Giotto said:

I have been researching a technique to get really rough texture, like with stuff coming out of the clay, that is often achieved by wedging in granular feldspar, which melts out during the firing.  I am very interested in very rough surfaces (lava like) in the clay itself prior to glazing.  I heard of people wedging in certain ground stones.  If you have specifics in using the granular feldspar or any other ground stone (amount used per pound of clay, and what firing temp) I would be so very grateful.  I typically bisque at 04 and fire to cone 6, but am also interested in doing single firings, as I will not be glazing but just using stained slips.

Any information you can provide or a direction you can point me to will be invaluable:

I have created rough surfaces on clay bodies fired to cone 10, cone 5, cone 3, and ~cone 06 (Raku items) by creating paste applied to the surfaces of normal commercial clay bodies;  the paste is the commercial clay bodies added with such ingredients as coarse crushed rocks, coarse iron ore, crushed wood, grass, pine needles, pine cones, dried and fresh tree leaves, leaves from bamboo, crushed bamboo, dried rice, pecans, iron filings, aluminum filings, rope, cloth, crushed cement, copper wire, nails, and anything that I saw worth playing with, including lumps of dry (and/or bisque) low fire clay bodies placed in cone 10 paste; lumps of dry (or fired) glazes sometimes work also.  apply the paste while the ware is still wet; leather hard and later has been too dry for the items I use this technique and the paste peals off when dried.    

the reason for using paste is to have control of where the effects are for decor without loosing control of the supporting part of the ware.   

some outcomes were "very interesting", some was "a mess", and some was "so what".    

 quickly started using small items to avoid the "so what" and the "mess" outcomes on larger items.   

I vaguely recall reading "The Additions to Clay Bodies by Kathleen Standen" ten years ago;   I switched to paste mixtures to get control of ware that could be more than just sculpture. I have several drinking and container items that has both interesting exteriors such surfaces and are still "functional" for drinking and/or holding liquids.   

Always get permission from the person who runs the kiln for both the bisque and the final firing. Some of the "additives" make "smoke and fire" that can be handled if one knows it is coming;  also be prepared to deal with runny liquids from some of the "junks" that are used. 
Also keep in mind that some "junks" are play nice alone and react a differently when too close to each other. 

LT

[PeterH]

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