Babs

Not sure but blue for me, I have to mix a little frit into the blue underglaze so it stays smooth under the glaze. A little of the glaze if it is a non run clear would also sort this. As it is not all over your blue dec. Could it be the rough patches are applied thicker when brush fully loaded? Or underglaze not stirred between brush strokes?

I am seeing the non glazed ring as a carved out ring to which the maker attaches a pedestal after the firing. Is that correct? If this is occurring in other platters, I would flick them on coming out of thr bisque firing to hear if they ring or thunk, ping or pung. The unevenness of thickness of clay. Proximity to kiln elements. Unevenness is in drying? Beuatiful onglaze decoration!

Also,if mending anything, the pot and mending paste have to be totally dry before refiring. Folk have had success, though not saying with yhis type of crack, dont know , Spooze with paper added.

Noticing there are tinges of green, glaze thinner? Near base edge of glaze and glaze flaw in handle. SG and glaze application of glaze same as in the testing in the alternative kiln? Re refiring the clay body, have you done this with the clay you are using previously? If you post what claybody you are using, someone may have experience with this.

I rhink you inadvertently did a reduction firing. Easy to do in a small gas kiln. Do you have time to refire one as a test making sure you have a fully oxidised atmosphere? With that amount of copper I could get black pots without trying in my gas kiln if not careful re atmosphere.

Do you have a pyrometer to log your kiln progress through firing? 1 cone is not usual practice. A bank of 3 cones one below target cone , target cone and one above the target. A bank of cones on each shelf to see how the inside of your kiln is behaving. Good luck.

What temp did it reach after the initial 2 hours? It will be interesting to see how your pots fared.

When I asked the question I was remembering a,lengthy posting on Zinc oxide. Fortunately? today I found I did have the dense zinc oxide in my supplies as well as a white powder. The dense Zinc Oxide was an off white, old supply. Recipe I was going to try calls for ZnO 25 Pot Feldspar 40 Ball clay 5 Calcite 15 Silica 2oo 15 What does anyone think..desc nice domestic glaze with the addition of 4 part iron..olive honey colour.

Thanks Callie, not going for a crystalline glaze but having written that, the glazes I was reading through were matte.

Just flicking through old recipe book. Can dense zinc oxide be substitued by zinc oxide? Can't remember if i have any dense left in my shed.

Thanks Min , will go with the same procedure as before, drat it!! Might unleash a new amazing range though! But .... It was a copper clear at c5 turning to a "matte" at refire to C03, slip added prior was a copper/ MnO2 thing, only on outside of pot .

To save time I was going to try a controlled cool of my normal C5 firing . My second question is will this jeopardise the otger glazes in my kiln.

Sorry, I glazed it fired it to C5, to maturity, then refired to C03 with added oxide brush work. The clear glaze turns "matte". Years ago... Now I am making 3 lids but only have the measurements of finished pot, photo, pot other side of the country. Just wondering if there is significant shrinkage occuring at the second glaze firing. And my other query. Thanks Bill.

I have been askedx100 to try to make a replacement lid for a teapot. That specific teapot was fored to cone 5 , clear green glaze,then fired to c 03 which made glaze a microcrustalluzed glaze,"opaque". Will that 3rd firing cause more shrinkage? Or if I do a controlled cooldown what type of glazes may also be altered in that process? Guy wants it quickly... I know, I know...

Looks like one man's collection of other folk's glazes, prob no text book as such Some are Bwenard Leach's , some are Val Cushings , you say they are your professor's so why not ask him?

Ifit was bisqued to a lower temp. it will take on more glaze if glazed as usual. Maybe test fire one glazed piece through a normal firing, place it on a clay biscuit to protect your shelf.

Get a meter and regulator, ( which you can adjust at fractions of psi ), in line, trying to regulate at cylinder too "gross" if thats the right word. Might be domeone who can send a pic of their set up. Psst, move your burner back a tad.:))

Think that's a must. I operated the first part of firing by using a pilot light, could be pretty vigorous but burner too vigorous for 1st part of my firing. After the cylinder regulator, inside my shed, a shut off lever, the gas control valve with pressure indicator was next, an air intake was next in line, then down to the burner. Never touched the air intake at burner. Just saying. Good luck. Depending what neck of the scrub you are in there would be gas firers nearby who could twig what is wrong in the setup you have. Have you been firing this kiln successfully and this burner issue has just arisen?

The image you show saying it is not backburning, the flame is orange and"woosy", not a fle I'd like to see when firing, what makes you write it is backburning with the blue flame image, is it making sucking back and gurgling sounds in the burner head?

A possible danger where it is is that the heat sensor / gas switch off mechanism may be affected by the interior temp of kiln emanating from the orifice not the loss of flame from burner. Do you have another air conrtoller up the line? Whats the flame path like inside and the suck of the stack/ damper at other end? Will be a play between all of the above

Back in the day , burner,shown is way too clise to kiln and is actually in the kiln, set it back out from the kiln a ways so air can be drawn in around the orifice to kiln and thus the flame. I'd start there, and flaps open as Mark says

No, freight not included in that amount! Just how it is here. Sheath for a long gas kiln s thermocouple, $70 many years ago...middle factor making the $

You haveto insert the wire as soon as you stop using the wax. If blocked hot soapy water and inserting and turning the wire a number if times would do the trick. A goid quality liquid wax would be the best. A hot wax applicator , used for batik art, a tjanting, is ok but need skill, eh !0

Yes the higher bisque is prob main reason if not the only one. Your ware would not have the same thickness of glaze and so would take on a different appearance. See the recent post re mistakenly firing to cone 5 bisque by Elaine Clapper Are your cones significantly different than previous firings?

Sounds for the best. The pointmade re electricity supply and 3 phase is worth noting. Unless your property has 3 phase supply best to stick with single phase kilns imo.