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Rick Wise

Wood Firing Tips

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I need some advice about preparing pots for a wood firing. 

All of my experience has been with making and glazing pots for electric kilns firing to Cone 6.  I will soon have the opportunity to put some pots in a wood kiln for firing.

Does anyone have any tips for me in terms of how to prepare the pots?  (I know, of course, that I need to make the pieces using Cone 10 clay.) 

In particular -- I think I have read that the ash from a wood firing can itself make a glaze on an otherwise un-glazed pot.  Is that correct?  Should I put some in without glaze?

Should I try some of my reliable home-made Cone 6 glazes and see what happens in the higher temps?

What can I do to maximize my output from this rare (for me) opportunity to do a wood firing? 

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The ash will affect the surface of the pots, and it could be directional.   If you have access to some cone 10 glazes use them.  I have glazed the inside of my bottles, jars, cups - anything I wanted to make fully glazed and food safe, then put flashing slip, oxides or nothing on the outside and let the fire do as it will.  If you have seashells to put on top of the wadding, you will find it makes an interesting affect.  If you want to try some cone 6 glazes I would suggest you put them on the inside of your pots only.  That way if they run because they are being fired too high they might not hurt anyone else's pots. 

Nancy

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The seashell is supported with wadding, sandwich the seashell between the pot and the wadding. Cockle shells are good, you want the shells or pieces of shell big enough so that the flame can work along it to make distinctive pattern (if you're lucky). After the firing any stuck on bits can dissolved by soaking the pot in water. The place you are firing at might want you to use their wadding.

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If you want to "capture" to effects of the flame you should try a good carbon trap shino. If the kiln owner doesnt have a shino its quite easy and rather inexpensive to make. Some of the most beautiful oranges ive had at cone 10 came from this glaze.

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7 hours ago, Min said:

The seashell is supported with wadding, sandwich the seashell between the pot and the wadding. Cockle shells are good, you want the shells or pieces of shell big enough so that the flame can work along it to make distinctive pattern (if you're lucky). After the firing any stuck on bits can dissolved by soaking the pot in water. The place you are firing at might want you to use their wadding.

I couldn't have said it better, thank you Min.

N

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Pots for a wood kiln need to be sturdy. If your usual work for cone 6 is thin-walled and delicate, these pots will not fare well in wood firing. Temperature is much more unpredictable and uneven. One half of a pot can be fired hotter than the other half. So there’s a lot more warping and uneven shrinkage, and sturdy pots can handle this much better than delicate pots. So make sure your walls and rims are sturdy. And for the same reasons, do not try to make flat pots like plates and trays. It’s very likely they will emerge too warped to use. If this is a rare opportunity, don’t waste it on plates! 

Design your pots with horizontal surfaces like shoulders and lids. These surfaces will catch a lot more fly ash. 

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In my experience clay bodies make a world of difference.

I've seen porcelains/porcelaneous clays do well but the ones that stand out are the more dark, iron bearing clays. Soldate 60 is a good example. Some buff stonewares show up nicely as well.

Flashing slips will help. Helmar or Gold Art type clays make a good start.

Get involved early. Grab the ruler and help organise the pots - or show up late. Either way you will have more control over where your pots will sit.

Keep an eye on the folks in the kiln - ask them if they want another shelf or maybe a cookie. It's going to be a long day.

Have fun!

Edited by C.Banks

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58 minutes ago, C.Banks said:

Keep an eye on the folks in the kiln - ask them if they want another shelf or maybe a cookie. It's going to be a long day.

Have fun!

When you say "Cookie" , do you mean the small piece of ceramic, used to raise pieces off the kiln shelves, or the baked good?

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I got a chance to participate in my first wood firing this past summer. it was great. i'd say definitely try to get some pieces in different places in the kiln so you can see what it's like for something to be by the fire box or in the back and how that affects how much ash they get and how much that ash melts. also try to wad things in different ways, i had some pots that were wadded on their side vs just on the bottom or with shells or with a ring of wadding vs a blob of wadding. definitely try some glazed vs un-glazed pots as well.

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large.1760393637_ScreenShot2019-11-01at1_05_08PM.png.25f12851c4e3be24f5088b04b498a91d.png

this little bowl has a shino glaze on it.

the pot behind it has a glaze to the shoulder the rest is from the ash.

 

large.1698358284_ScreenShot2019-11-01at1_05_22PM.png.1acb5dd00db669b19cafc0ac8296e4dd.png

these cups are all un-glazed on the outside. some slips applied to the two on the ends.

large.900882309_ScreenShot2019-11-01at1_05_35PM.png.9ad0080c82bef2360bc8c66a8b603ce7.pnglarge.1217936280_ScreenShot2019-11-01at1_05_47PM.png.f3fe86be6debd9fd791f092bfa925ebc.png

this bottle was fired on its side and is un-glazed. just the natural ash glaze. has a really wonderful drip that formed from being side fired.

Edited by akilspots

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On 10/31/2019 at 3:52 PM, Rick Wise said:

Should I put some in without glaze?

Should I try some of my reliable home-made Cone 6 glazes and see what happens in the higher temps?

What can I do to maximize my output from this rare (for me) opportunity to do a wood firing? 

1.  Yes

2.  Yes, but put them on cookies/in saucers, so if your glaze runs it won't ruin shelves.  I used these tubes, and stood them on the unglazed trays.  Only needed to apply wadding to the trays, not 30 odd samples!

3.  Be open minded to results. Take it as a learning experience, not a new production method.

large.20181008_124154.jpg.faf9a65d345326large.20181008_021556.jpg.6b02a1cc9bc991

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When I participated In Simon Levin’s wood firing, I asked the same question. They had a few reliable glazed there for glazing, but with wood firing the form and any surface design will really be magnified with the collection of ash or flashing from the flame path. Most of them look the best with minimal or no glaze at all. I would strongly discourage using a cone 6 glaze, and also a glaze you haven’t fully tested in reduction. Perhaps the person organizing the firing can allow you to experiment with some of the glazes they trust in firing. Adding all of that ash collection with your lower temp glazes could potentially drip down onto other pots. You will also learn more about the firing based on the way the pots look in varying parts of the kiln. 

The placement of the wads I find to be a fun way to experiment with the flame path and surface decoration. (So no glaze ... you never know what spot that pot will fit and how it will need to be placed) 

 

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go to YouTube and watch as many wood firing videos as you can..  you will get a good idea of how to place your pot for maximizing the ash contact..  the kiln will have sweet spots where the pots naturally get more ash or you can put your pot on its side . you "should" get 1 ash glazed side and 1 that is not.. if you place your pot on its foot, your foot may turn out really awesome but you cant see it as the pot sits on it...

 

your asking for problems with a cone 6 glaze- you wont be happy..

 

maximizing the output-  if it were me, i would be happy as could be to simply be part of the firing. learn as much as you possibly can, be there on site as much as you can- i would keep every pot if it were me.. not many wood firings in my area..

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On 11/12/2019 at 3:50 PM, Crusty said:

your asking for problems with a cone 6 glaze- you wont be happy..

 

Some of my ^6 "oxidising glaze samples came out better for a ^13 wood firing.  You never know until you try, but you have to do it with care and consideration for other kiln users.

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On 11/1/2019 at 12:11 PM, akilspots said:

large.1760393637_ScreenShot2019-11-01at1_05_08PM.png.25f12851c4e3be24f5088b04b498a91d.png

this little bowl has a shino glaze on it.

the pot behind it has a glaze to the shoulder the rest is from the ash.

 

large.1698358284_ScreenShot2019-11-01at1_05_22PM.png.1acb5dd00db669b19cafc0ac8296e4dd.png

these cups are all un-glazed on the outside. some slips applied to the two on the ends.

large.900882309_ScreenShot2019-11-01at1_05_35PM.png.9ad0080c82bef2360bc8c66a8b603ce7.pnglarge.1217936280_ScreenShot2019-11-01at1_05_47PM.png.f3fe86be6debd9fd791f092bfa925ebc.png

this bottle was fired on its side and is un-glazed. just the natural ash glaze. has a really wonderful drip that formed from being side fired.

Thanks for these pics.  Makes me think -- I can apply some slips to get color variations rather than use glazes, right?  As long as the slip is from cone 10 clay I have no worries re runs (?) Right?

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I was completely new to wood fire with these pieces:  Porcelain form with only the black from the fire; stoneware piece with gray celedon and the orange fire color; stoneware bowl with white inner glaze, unglazed around the middle and gray celedon at base, and;  underside of a porcelain catchall, with light green celedon and the fire color. I used Troy wood fire stoneware and Cool Ice porcelain and commercial cone 10 glaze.  These pieces were positioned in the kiln so as not to get lots of dark brown/ash all over them. For me, using cone 6 glazes in a 10+ fire would be too much of a crap-shoot unless I was well-versed in the individual glazes and OK with loss through experimenting.  

Flower and Ash-.jpg

20171105_182832-.jpg

BW 5a-.jpg

CA 33f WF-.jpg

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Another question about Wood Firing:

Typically, in a wood burning kiln, have the pots been bisqued or are wood firings usually single firings?  And if bisqued, does that mean (typically) that the potter has used an electric kiln to bisque and then wood fire only for the glaze firing?

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It depends. I did maybe a double handful of wood firings in college.  Things were always bisqued in advance because there was transport involved from AUA out to the Banff Centre. There was a Fast Freddie in the kiln yard at school, but it was less desirable to use because we only had easy access to pallet wood, and getting permission to access the kiln yard  overnight from admin was a right royal pain. We still bisqued the pots that went in that kiln though, because there were enough barriers to using it on a regular basis that the relatively volume of pots going through it didn’t encourage a lot of in-depth exploration. 

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They can be either bisqued or singlefire.  I do a wood fired bisque.... yeah I  know but I dont think they make a hobby sized kiln to fit all the stuf I have to make to fill my kiln. The only precaution would be to introduce plenty of air from about 011 on up to bisque temp. This greatly reduces the risk of bloating later during the glaze firing.

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The worst thing we have found when you wood-fire raw pieces, is attaching the wadding.  You have to push it onto the base of the pots, and handling raw clay is already treacherous without trying to stick something else to it.

Try it, but make sure the clay is properly dry, or candle overnight.

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