Hey lovelies!
So I bought a glaze that… does not do what I was excited about it doing in our standard firings. Figures, right? I’m gonna try it out in a cone 5 firing whenever we do one of those again and see how it fares there, BUT. The label does say all the fun phase separation stuff happens when the kiln cools fast.
Would a rapid cool firing be a possibility for a specialty firing? Like are other people even interested in doing one?
I don’t know that there is such a thing? the heating stops at the top temperature and then just cools straight down from there unless you purposely slow it down…
When I think “rapid cool,” I think the fastest would be like in a raku or something?
You might check with the manufacturer and see what they consider “rapid cool”. We normally do what I’d call a “standard” cool – the kiln hits top temp, and then cools naturally. We could conceivably speed that up somewhat by removing all the peeps, and possibly lifting the lid a bit – there’s a brace that you can do to achieve that. Right now we have rules against speeding up the cooling that much because some people believe that rapid cooling may cause crazing (cracks in the glaze). However, if everyone in the firing accepts that crazing may be an outcome, I personally don’t see any reason why we couldn’t.
Raku firing is a rapid heat, and then you remove the pieces from the heat. And, that does tend to cause crazing. That’s one of the reasons raku ware is strictly decorative/not food-safe. Traditionally, you dump the hot ware into some media that will catch fire. The carbon fills the cracks of the crazing and produces part of the distinctive raku “look”.
Amaco, Coyote, Laguna, and Spectrum all have Facebook groups where people discuss the glazes. The Amaco group is the most active, but I see questions regularly on the other 3 forums as well.
What glaze is it?
The glaze is Sexy Mermaid by Midnight ceramics.
“Cone 5/6
Sexy Mermaid is a semi-opaque floating blue glaze with opalescent light blue streaks on an emerald background. The glaze gets darker and more opaque when applied thicker or over texture. When cooled more slowly, crystals grow in the glaze, causing it to become a matte olive green. When cooled naturally, the glaze remains shiny and more transparent. Product images show 3 coats of glaze. This glaze is runny when overfired or overapplied.“
This is what’s advertised:
But this is what’s coming out of the DMS standard firings:
(I’ve had another piece in a separate firing with the same result)
Like I’m not mad at the shade of green, it’s nice, but I specifically bought it because I was in love with the blue float on top of the green!
Cool, I have Canadian Tuxedo and Witching Hour by Midnight ceramics:)
The regular cool is what we do in our community firings, slow cool is a specialty firing, I believe we decided in the last meeting that the June firing will be a slow cool.
I could probably get a similar result by layering amaco indigo float over it, but the whole point of buying the mermaid glaze was the fun results I was supposed to get with a single glaze! Like this:
I think it looks so neat because you have tons on texture on your piece, that affects the flow compared to their piece which is relatively flat.
You may need to try a whiter clay… There may be things causing it to do that in White Stoneware, which I have found in the past…
Or like Beth said, you might ask the Midnight Ceramics People to see… Show them your picture…
And… you might try thicker coats next time? I have one of their glazes too, and I feel like it should’ve been for dipping… It was really runny and hard to brush on. So maybe it needs to be thicker?
Yeah all valid points, maybe I should try it on a plain white stoneware thing! Thanks guys, I appreciate the helpful input, still learning all this stuff <3
I have this dream of making a huge yarn bowl out of speckled clay and only glazing the inside, with something cool and floaty, was kind of hoping this glaze would do the trick but I may have to reconsider 
Interesting!
Says the clay body on the cup is a dark clay.
Yes, dark clay with a white clay handle 
I have read about a “rapid” cool technique were you open the kiln at like a 1000 degrees to rapid cool but I don’t know I’d recommend it especially in our setting. There are glazes formulated for controlled cooling which we have tried a couple times where you cool more slowly to allow glaze to develop.
