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Soldate 60 is great stuff. It's a cone 10 clay but for sculptural firing to midrange would work too. I've known people use it for Raku firing also.

Could go faster to 1500F then resume your regular schedule. edit: I just read your other post about this in the another section, given they are very important pieces the safest bet would be to do the same schedule but without any candling (if you did this). Maybe go a bit faster but not breakneck speed. I'm going to delete your duplicate post.

This thread is a continuation of this one started by @Mark C. regarding the addition of another K2O feldspar to replace Custer: Vardhman feldspar from India. Chart comparing Vardhman with other potassium feldspars plus the analysis I received from Vardhman.

I have the analysis for Vardhman, I'll add a pinned thread on potash feldspar changes. edit: Pin link added here. https://community.ceramicartsdaily.org/topic/41698-potash-feldspar-comparisons-of-custer-mahavir-g200eu-and-vardhman/

Good find Peter. When I look at the analysis for both there are other differences too though. Definitely a fragile mechanism to get the green. Reitz Green with Gillespie doesn't need the lithium carb and dolomite additions when I played around with altering the recipe, the silica is a tiny bit higher in the Gillespie version but given the differences in the Floating Blue recipe that might or might not be consequential, I don't know. A simple addition of iron with a reduction of cobalt would be simple to test Hansen's theory if it translates to Reitz Green also. I suppose RIO would be the logical material to add as long as speckles don't become an issue. Or black iron oxide might be better if you have it.

I would. 1550F is approx cone 012 so pots are going to soak up glaze much faster than a typical 06-04 bisque.

@oldlady emailed me photos but was unable to post them here. These are her photos and show where she has reglazed some areas.

Is this the original you were using? I've also seen this with 1 rutile.

What have you supplied the boron with so far? Same really high alumina? Same batch of rutile?

It might just be as simple as thinning down the underglaze with water and applying 2-3 coats to get the opacity of colour you are looking for. If underglaze is applied too thick it can definitely lift from the clay. What works for me is putting the first coat on fairly thin then when that layer is dry I apply another 2 coats to get an opaque coverage. I mostly use Spectrum underglazes but have also used Crysanthos, Velvets, Speedball, LUGs and homemade underglazes. The only time I don't water an underglaze down is when doing an underglaze transfer.

Is it just the tiny bit of GB you are replacing?

Hi Steph and welcome to the forum. Linda Arbuckle pdf with a good recipe on page 4. What is helpful from this pdf also is the troubleshooting tips on page 3. https://www.lindaarbuckle.com/handouts/slips-and-engobes.pdf Which brands and colours are burning off?

If the SG was 1.36 to start with but seems thinner now it's probably just because some of the solubles in the glaze deflocculating it.

If the bottoms are a bit warped and you want to level them out you can use a diamond flat lap disc to do that. I stick one onto my wheelhead just by using a (knockoff) Xiem BatMate and water, could also use a pad or donut of clay. I dribble water onto it while the wheel is going at near full speed. It can take a few minutes to grind the bottom level but it works, makes the bottom really smooth too. I have 2 flat lap discs, one is 80 grit the other 100. The 100 grit is a better quality (more expensive) one and works better. I can post them here for you if you can email them to me. I'ld be super cautious refiring ware that has been used. Unless it's completely dried of all moisture it can give some really bad blowups in the kiln, especially if it's quite a tight body with low absorption, makes it harder for the moisture to escape.

Just to clarify the options are to spray on some more glaze and refire to cone 5 or cone 6? Risks are applying too much glaze? I don't know how that clear fires at cone 5. It would probably be okay but I'm not certain of this. Perhaps placing it in a cool spot in your kiln and do your usual cone 6? Glad that high calcium clear is working well for you!