Does bone ash still flocculate without clay?

[Beebop]

If a glaze sources all its Al and Si from feldspar and does not contain clay, will bone ash still cause over-flocculation? I am assuming it’s the interaction of P+ with the clay particles that causes it, just wondering if eliminating clay is a possible route to avoiding gelling in the bucket for bone ash glazes. Or will this just lead to hardpanning? Thanks! 

[Min]

This isn’t something that I would do for a couple reasons. First off having clay in the recipe will help both with the bond of the glaze to the pot and prevent it being really dusty. Secondly without clay in the recipe you’re going to need a heck of a lot of feldspar to supply enough silica and alumina, this will probably result in a glaze with very high levels of potassium and or sodium which in all likelihood will craze quite severely. 

To resolve the over flocculation that bone ash can cause I would leave the recipe as it is and add just a tiny amount of a deflocculant such as Darvan or sodium silicate. I would try just a small amount of glaze first, try this and see if you like the application.. Another solution would be to just mix up enough glaze for immediate use. For dipping this might not be practical but for pouring or spraying it should be okay.

[Beebop]

Ok good advice. Thanks!