Re-firing Shino

I had some blistering on a couple of my saggar Shino pots so I decided to re-fire them to Cone 06 in oxidation using a low fire glaze to cover the blisters.
The pots in the center are the re-fired pots and those on the outside are pots that were fired at the same time, but not re-fired.

As you can see, the iron really got activated in the oxidation re-firing, but the pots didn't lose all the carbon trapping.

The amber colored glaze at the bottom of the mug and on the back of the cup is the low fire (commercial) glaze intended to fill in the craters left after I ground off the blisters. Next time I'll grind a little better...

One more saggar Shino

Malcolm Davis Shino saggar fired to Cone 6 1/2 in an electric kiln. I put two pieces of charcoal cut in half and about 1/3 cup of wood chips in the saggar this time. The glaze was brushed on the outside and the liner is MC6G Raw Sienna. I spattered some wax on the outside of the pot this time. I definitely need more experimentation with this as I'd like to get a result in between the last firing and this one.

Another Saggar Shino test

Malcolm Davis Shino saggar fired to Cone 8 in an electric kiln. I only put one piece of charcoal and about 1/3 cup of wood chips per saggar this time. The glaze was brushed on the outside of these pots. I poured Penn State Shino inside.

The only carbon trapping on the left cup was on the handle, which was right above the lump of charcoal. I guess I need to make sure to spread the charcoal out and I should probably use one and a half or two lumps in that saggar next time.

The other side of the cup on the right has almost no color (it all looks like the far right of the cup in the image above). The saggar it was in is a bit larger that the sagger used for the cup on the left and the charcoal and almost all of the wood chips were on the side that got color. I'll definitely put two lumps of charcoal in that one next time and make sure to spread the wood chips around better. It's kind of amazing to me that the atmosphere in a small sealed saggar would be so strongly affected by where the combustibles were located.

By the way, I was able to save the fiber blankets from both saggars this time by peeling them off the tops of the saggars very slowly and carefully.

Electric Saggar Reduction

I made a couple of saggars for testing reduction in my electric kiln. I sprayed Malcolm Davis Shino with Redart on the outside, Coleman Tea Dust liner. (Note to self - the shino had been sitting around for a couple months)

The saggars are cylinders about 8"x8". Inside each saggars, I put about 1/4 to 1/3 cup of wood chips, three charcoal briquettes, and a pot which was raised about 5/8" from the floor of the saggar on a clay "cookie" and triangle stilts. I put a layer of SuperWool 607 HT on top of the saggar (to plug any gaps) and covered that with a kiln shelf.

These got serious reduction. The Coleman Tea Dust is basically black inside except where the pyroxene crystals formed. The other side of the pot on the right is pretty much completely black. I'll definitely try with less combustible material next time. I also need to mix up enough Shino so I can dip the pots.

One other note. The fiber blanket stuck to the top of the saggar so it was ruined. The fiber costs $1.67 per square foot if you get it from eBay so it's not a ridiculous expense, but I'll probably try a strip around the top of the saggar next time to limit the amount of waste.


Before firing...

Old Stuff - Saggar

Saggar fired in Raku Kiln - approx Cone 010.
Fired inside saggar with Red Iron Oxide, Copper Carbonate, salt, and sawdust wrapped in newspaper. Finished with paste wax after cleanup.