Beebop

Ok good advice. Thanks!

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!

Do you think copper oxide be substituted for this purpose?

I added a new post with follow up questions. I’m very intrigued by this solution!

This is very helpful, thanks for the feedback. I’ve only been making glazes for a couple years now and haven’t had to rebuy anything yet except talc, which involved switching to Texas talc from another one that is no longer sourced, though I haven’t noticed much of a difference in performance. But now that I’m saying that I should go back and actually look at my recipes and results to see if there’s a correlation. It’s not that all my glazes have the same problem, but that most of my glazes have some problem, many of them being hard panning, pin-holing, crawling, cracking when dry, glaze fail caused by layering. I think a big part of my problem is that I need to work with a lower SG, and I have some other fixes I’m working on as well, though trial and error is slow when you do glaze firings at most every other month! I am definitely interested in using an additive I think that could go a long way for me in problem solving, added a new post with follow-up questions on that. Thanks!

I have follow-up questions based in recommendations from my previous post. I’m looking into MAGMA and CMC additives to improve the working properties for some of my glazes. I see that both thicken a glaze. Since the glaze+additive goes on thicker, does this cause a thicker glaze layers in the fired product? Or is the thickness entirely due to the organic that burns off, and it leaves behind roughly the same amount of glaze after firing? Should I be trying to dip quicker or brush fewer layers since the glaze is thicker, or apply as normal because glaze thickness is just not the equivalent when compared to a glaze without additive? Thanks the all the help, I learn so much each time I post I really don’t think I could be a glaze maker without this forum!

I have never heard of Magma but just looked it up and it sounds like a miracle! I will definitely give this a go! I have run into some really impressive problems with bone ash gelling, but this particularly one rendition has been ok. I’m still learning when something needs more/less water versus floc/defloc though.

That’s very compelling and makes a lot of sense. I’ll definitely give that a go. Thanks!

Good advice, I will work on sourcing silica and alumina elsewhere or calcining clay for problemtic recipes with high clay content. Thanks for the suggestions!

Good question. I have lots of kinks to work out in general, some are better than others. The first and the third one I posted (CGB2 from Hesselberth and Roy and a SiC-Jun in test/development phase) are two of the most problematic as far as crawling on the finished product. The fourth one cracks a lot on drying but rarely crawls, been trying out different EPK levels on that one from 0% to 20% to limit running. The second one is a kaki I’ve been developing, it rarely has issues with application or final defects.

I’m less asking about how to fix those specific defects and more wondering if there’s a benefit to using ball clay instead of EPK. I added screen shot of some recipes I use, usually EPK below 20% and bentonite at 2%. Thanks!

I use EPK in my glazes usually with a bit of bentonite, I don’t have any non-bentonite ball clay on the shelf. But should I? Would ball clay have better working properties for a glaze than EPK+bentonite? If ball clay is a must on the ingredient shelf, why and which one do you recommend? I seem to have issues with suspension and cracking/lifting during drying, not sure if that could be improved with a different clay. Sort of assume not but I’ve never used ball clay before so idk. Looking to place a materials order so if I were to try some, now is the time. Thanks!