Tuesday, February 2, 2010

Sifting ash ... and other glaze requirements





I got down to the bottom of the barrel - literally - with a number of my glazes after the January firing. So, with an inch or less of glaze left in several of the buckets, I knew I would have to do a marathon ingredient-weighing session - and a similarly long mixing and sieving and bucket-washing session - before I could glaze the pots for this next firing. (I hate this part of the process, by the way ... hate it.)
Hence today's photo of the cinders and ash in the sifter. I get wood ash from Falmouth friends Mie Elmhirst and Diane Salter, and from Dee's sister Ellen in upstate New York. All the ash comes from their woodstoves and is mostly the result of burning hardwood. I sift out the cinders, bent nails and door hinges interspersed with the ash (Ellen's husband Russ will burn just about anything falling apart on their farm). If I do it in the studio, the place fills with a fine fog of ash, so I try to do it outside, where the wind will take away the lightest ash. That's what I did today, freezing my hands.
The ash is mostly used in my version of Phil Rogers's "Standard Ash Glaze" from his first book on ash glazes. Phil washes most of his ash, or at least he did when that book was released. But I found that washing ash was an aggravation, so I've been using it unwashed for more than 10 years. It runs a bit more than washed ash, but I double the amount of China clay in the recipe and that seems to keep the running under control. The glaze makes a lovely transparent celadon over my white B-mix stoneware, and a green and runny glaze on the more heavily grogged brown stoneware.
Onward to the Shinos ...

18 comments:

Tracey Brome said...

I should send you some of our ash to try. We cut up a fallen red oak this summer and are burning it during the cold and snowy days.It burns really hot and for a long time, great hardwood! I'm with you on the glaze mixing,I just hate all the clean up you have to do with the buckets. Of course I hate everything about glazing! I'm loving this terra sig/sawdust thing, very little trouble with great results!

cookingwithgas said...

I find it funny that we all would rather do this then anything but most of us have jobs we don't like!
Love that pot- nice and rich...

Ron said...

Those pots are beauties. Good luck w. all the mixing!

FetishGhost said...

Those beautiful surfaces are worth the extra effort. We have to call chores like sifting ash "the glory" jobs around here. The semantics seems to help.

Hollis Engley said...

Well, I'm about halfway through this particular 'glory job.' I've got buckets lined up with dry ingredients in them, which I'll wet down tomorrow morning. And I'll mix up a few test glazes, things I've wanted to get into my palette here. Thanks for the ash offer, Tracey. Save me a couple of buckets and I'll pick them up when we come down for the show in the fall.

Dan Finnegan said...

What's the red at the base of the first vase, Horace, it looks sweet!

Hollis Engley said...

Hey, Dan. That's a so-called "Malcolm Davis Red Shino." Its effectiveness seems to come and go with each batch, but that particular one did some nice silky surfaces and lovely oranges. And bananas ... no, actually, no bananas ...

Amy said...

How interesting about the ash. I just sifted some wood ash too, given to me by my dad from my parent's fireplace. I ended up sprinkling it on top of some shino glazes on yunomis. Sounds like you mix yours into the shino. Is that right? I have so much to learn.

Hollis Engley said...

Hi, Amy. No, any ash I use with Shinos gets sprinkled on top. It melts in and leaves a nice gray texture over the brown or gray Shino. I use the ash mostly for the glaze you see on the vase and bowl in the two photos. The lower part of the vase is an orange Shino with no ash in it. And there's always more to learn, isn't there?

Linda Starr said...

I love that orange shino and ash contrast in the top pot, lovely. I don't envy you the mixing though.

ang said...

my ash glaze only has 2 ingredients and i usually use it on sculptural forms so i never really worried about its performance..any tips on what else i can add, just some ball clay or china clay?? i fire it at the mo to cone 7....love your pics..

imagine said...

Wow! That bottle is just so beautiful.
It's a long time since I have seen a pot of that quality.

Hollis Engley said...

Coincidentally, John, I had the Imagine blog up on my other screen when I read your comment. I love the big sculpure pieces taking up the whole inside of the truck. And thanks for the nice words. I made that pot a few years ago and it's long since sold. But looking back to where I was helps me see where I"m going.
Ang, I add the china clay to keep the ash glaze from running off the pots at cone 10-11. I wouldn't think you'd have that problem with cone 7, though I guess it depends on ingredients. I can send you some recipes if you'd like to see them.
And Linda, it's hydrating day today. Gotta hook up a hose to clean the buckets outdoors. Bummer ...

ang said...

hey hollis it does need tweeking a bit my last fire it ran like crazy, i'd appreciate some ideas for adding to the recipe thanks..mine is just ash and gerstley borate 90/10 at c7 plus copper

明白 said...

我愛那些使自己的德行成為自己的目標或命定的人 ..................................................

Lee Love said...

One of my jobs during my apprenticeship was preparing wood ash for glaze use. We would spend months, adding water, siphoning off the top water after settling and then adding more water. In the beginning of the washing, we might draw off water 3 or 4 times a day. Early on, it is wet sifted several times through 200 mesh screen. We would throw away the sand in the ash. The resultant ash was a lot like terra sig. When I sift my own wood ash, I am always transported back to those times...

Hollis Engley said...

It's a lot of work, isn't it, Lee? My impression is that washing the ash that much eliminates a lot of the runniness of the ash glazes. Is that what you found?

Lee Love said...

Hi Hollis, It can, but Shimaoka's glazing technique over inlay and the traditional wet measure requires it for consistency. When we started a glazing session, we would always scoop off the water on the top of the glaze bucket and then add a set number of ladles of water back. We glazed the smallest/thinnest work first, because it required the thickest glaze (not enough clay body to draw enough water.) We then added water to the glaze as the ware got thicker, always scratch testing the thickness of the glaze. Everything was wet sponged before glazing (that was one of my glazing jobs.)
We also altered the kaolin content from 5% in the coolest part of the kiln to 25% in the hottest part of the noborigama. Also all glaze was mixed by wet measure, slaking the material before it was measured by wet ladle full to be put into the glaze mix. Soluables change the apparent thickness of the glaze.
One way to get the soluables back in is simply by having a bucket of soda ash solution and dipping the pot in it before glazing or spraying it after glazing.