petrichor Posted June 10, 2021 Report Share Posted June 10, 2021 Hi! I quite enjoy using wild clays: I use them as clay bodies or in glazes. I have found lots of black clay in the sea and I wonder if I can use it or if the salt content can damage the kiln? I could try and wash is, but I cannot think of any way to only wash out the salt and not all the clay, too. Link to comment Share on other sites More sharing options...
Mark C. Posted June 10, 2021 Report Share Posted June 10, 2021 Salt will not be good for kiln-soak the clay in freshwater then dry it out as an idea to get any salts out of it. Link to comment Share on other sites More sharing options...
PeterH Posted June 10, 2021 Report Share Posted June 10, 2021 FromDigitalfire's page on efflorescence https://digitalfire.com/glossary/efflorescenceSoluble salts can also be removed by slurrying a clay using excess water, allowing it to settle and pouring off the stained water (and repeating as necessary). I'm dubious about the advice because of the potential loss of "fines". What do others think? Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted June 10, 2021 Report Share Posted June 10, 2021 If you’re just siphoning the water off the top, you don’t have to loose any fines. Link to comment Share on other sites More sharing options...
neilestrick Posted June 10, 2021 Report Share Posted June 10, 2021 I would definitely be concerned about the salts damaging the inside of the kiln. I would also be concerned about how it affects the clay. Typically, soluble materials are not wanted in a clay body. It will likely affect the workability of the clay as well as how it fires. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted June 10, 2021 Report Share Posted June 10, 2021 The salt is bound to affect thixotropy. You might be able to pull it off as a slip or a glaze. But as Neil says, it’ll probably be hard on the kiln. Link to comment Share on other sites More sharing options...
petrichor Posted June 11, 2021 Author Report Share Posted June 11, 2021 Alright thank you! Alas, I also think so. I read that the salt can react in a pretty undesirable way and even make the fume more toxic. I was also a bit unsure what happens if I just water it out: would I just sit back with fine sand, basically? But I will try and I will fire it in my almost broke outdoor kiln and see:) Link to comment Share on other sites More sharing options...
PeterH Posted June 11, 2021 Report Share Posted June 11, 2021 1 hour ago, petrichor said: Alright thank you! Alas, I also think so. I read that the salt can react in a pretty undesirable way and even make the fume more toxic. I was also a bit unsure what happens if I just water it out: would I just sit back with fine sand, basically? But I will try and I will fire it in my almost broke outdoor kiln and see:) You can do a sedimentation test by shaking up your clay/soil with water and letting it settle, the different sizes of particle separate out into layers: This is a variation on the theme, separating the clay from any sand (and washing it the process).Processing Clay the Easy Way: Water Extractionhttp://www.practicalprimitive.com/skillofthemonth/processingclay.html Link to comment Share on other sites More sharing options...
Min Posted June 11, 2021 Report Share Posted June 11, 2021 There is an excellent article here for testing wild clay, well worth the read. What type of kiln are you firing in? Link to comment Share on other sites More sharing options...
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