Midfire Clay Short When Recycled

[ArtyPartyTeacher]

Hey everyone! I run a high school studio and have been using cone 6 Highwater Desert Buff, mainly because that's what was left when I took over the position last year. I find that when recycling the clay, it is coming up short and losing plasticity. I reclaim bone dry clay with throwing water to maximize the plasticity. On 'For Flux Sake', they mentioned some commercial midfire glazes have nepheline cyanide instead of potassium based feldspar. Due to it's relation with sodium, it is causing a lack of plasticity during reclaim and even in some cases growing hair on drying pieces(which is happening as well). All of this to say, has anyone else been having trouble with this clay keeping a good plasticity when reclaiming? Do you have any tips or any other economical midfire clay recommendations for a working community studio? Thanks everyone! 

[Min]

Hi and welcome to the forum.

Just to clarify you are slurry mixing the slaked dry clay and including throwing water? If this is the case then adding some more plastic materials can fix this but I would test the reclaimed batch for absorption in case it also needs a top up of flux.

For slurry mixing adding a 2-3 percent of bentonite (by dry weight) will get it back to being plastic. Easiest way to get the bentonite to mix with the clay slurry is to put the dry bentonite into a  container of super hot tap water then whiz it up with a hand/stick blender for 10 minutes of so. It will turn into a very thick sludge, add enough water to make it like yogurt consistancy then add it to your clay slurry and use a drill with a jiffy mixer attachment (or similar) and whiz everything together. Tony Hansen from Digitalfire recommends dry mixing the bentonite with ball clay at a 1:1 ratio and using that. I haven't done this so can't comment on how well it works but basically doing the same thing.

If you already have a batch of processed reclaim then try wedging in about 20% new clay, this might be enough to bring it back to a workable condition.

BTW it is common to use nepheline syenite as a body flux.