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Newbie - Pit Firing And Wood Ash Glaze


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Hi everyone!  I'm new here so just going to jump right in with intro and questions all in one. 

I'm Native American and have been working over the past decade to get back in touch with my culture, which includes taking much of my craft work back to primitive methods.  The pieces I make are intended to be saleable at the events I attend where I am a storyteller/teacher/musician and a firekeeper.

 

Recently, due to health issues and financial issues (which are largely due to the health issues) I was forced to cut back on my crafting due to expenses and limited energy/physical ability, so I have gotten back into pottery.  I have not played with clay seriously in over 30 yrs, and back then we're talking high school pottery/art courses.  I remember a lot and online study has helped me to brush back up on most aspects, but I have never tried primitive style before, nor do I know anyone who has... so I'm still feeling a little nervous and could use a little help.

 

I was working to harvest raw clay from the soil to use for this project until I got sick and was forced to ease up on the physical work involved, so I went to the only pottery shop I could find within 3 hrs of home and bought two 30 lb blocks of clay, one of them is terra cotta and the other is a gray clay that dries and fires white, both low fire clay, on the advice of the shop worker, after I explained I intended to use only pit firing and ash glaze that I will mix myself (yes, he tried selling me a lot of stuff, glazes included, haha). 

 

I discovered I don't care much for working with the terra cotta for the small pieces I wish to make, though I did manage 1 small coil built bowl that didn't turn out too terrible.  This clay is not very plastic and cracks too easily for my liking.  It's also a bit "rough" for the pieces I wish to make (small bowls, mugs, vases, jewelry pieces/pendants, beads, etc).  The gray clay is much better, smoother, and more plastic, much easier to work with.  I will include a few pics of the stuff I have made thus far.  (please be gentle)  

 

Right now everything is drying.  The last 2 bowls are close to leather hard and I expect to finish those tonight/tomorrow, and I am planning to force dry everything in the oven tomorrow afternoon for a couple/few hrs.  (have never done that before either)  After everything is dry I plan to start my first pit fire, and this is where the nerves are taking over and the questions come in. 
1.  I've noticed in all of the videos I've seen of this method that the fired pots come out black.  Is this permanent or is this supposed to get rinsed away and then dried before glazing?  Nobody explains that part.

 

2.  Can I ash glaze greenware and fire it just once and call it done?  Will that work?  Or is it vital to fire to bisque and then glaze, then fire again?

 

3.  Since this is pit firing and I won't have any temp gauges or controls, how do I know if I'm getting the fire/coals hot enough for everything to be fully fired?  How long to fire this stuff?  (yes, I will do test tiles but each fire will be different so those will be limited help)

 

4.  Any tips on the wood ash glaze?  I purposely burned exclusively maple wood, bark, and leaves about a week ago, then collected and saved the ash for glaze.  It's still sitting in the container, dry.  I want as much raw color as possible so I don't intend to rinse it, but do I have to sift it?  What are the risks of not sifting?

 

5. I've been reading up on burnishing, but can't find any info about staining and glazing over burnished surfaces?  Must the burnished piece be fired and then stained/glazed or can I do that all at once?  Can that all be done in 1st/only firing?  Burnishing the insides of bowls?  (is that even possible without breaking them?)

 

6.  Do I need to worry that stacking the pottery in the pit will damage the glaze with debris from the fire?  (I'm assuming everything burns off at those temps, but will it leave pock marks, etc. in the glaze?)

 

7.  I feel like I'm forgetting something but totally lost as to what that might be.  This has all been experimental thus far but I'd like to keep doing this long term, learning as I go.  I have a couple of things I've made that I am worried about losing as experiments so want to do everything I can to see to it they survive.  1 is a "moccasin pipe" that I don't think I could easily attempt to replicate.  Anything anyone can offer for suggestions, tips, etc. to help see me through this would be much appreciated. 

 

Thanks in advance to anyone who can offer up some guidance.  I need to make some money with my work so I can pay off this stack of medical bills, so the work has to be quality.  That's hard to do when a newbie and this nervous.  Thankfully I'm a quick study and spent 6 months researching before I even bought the clay.

Here are pics of what I've made this week:

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post-79534-0-76475000-1473921097_thumb.jpg

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post-79534-0-55320300-1473921238_thumb.jpg

post-79534-0-77044700-1473921043_thumb.jpg

post-79534-0-76475000-1473921097_thumb.jpg

post-79534-0-90743500-1473921134_thumb.jpg

post-79534-0-55320300-1473921238_thumb.jpg

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Most of the pit/sawdust firing I see is burnished which gives a lovely soft finish to the pots. Colours can be produced by adding oxides to the firing . Customers must be aware that the pots will not hold water. They are also fairly fragile. You might try googling Laura Wee Lay Laq and have a look at her work for burnished pieces.  Lin

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Here is what I think you should do:

 

Dig a slight pit or use bricks to create a fence.

Put about 2 inches of wood shavings or sawdust in.

Partly bury the pieces in. The parts that are buried will turn permanently black. The tops should be grey-white-clay colored with some variations. If you add some copper (carbonate or sulfate) there will be reds in the top part as well.

Pile on wood.

Set it on fire. When it is really going, cover it with a sheet of metal.

Wait.

 

Pit fired pieces won't be vitrified. They will not have a glossy, glassy surface. They will not be sanitary by Western standards.

Your pieces will be more successful and stronger if you can get them bisque fired beforehand.

You do not need to know or control the temperatures reached.

Burnishing is done at the leather-hard working stage. It compacts the surface and gives a smoother finish. The smooth surface makes things prettier.

 

I recommend making jars. They work well in pit firings, are functional, don't need to hold water, and are not really for food.

 

And if you think making pottery is hard... the selling part is harder still.

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I like your pieces.

Just remember to take the sticks out of the beads as the clay will shrink as it dries but the sticks won't thus causing cracked beads.

I intended for the bamboo skewers and toothpick to burn out during pit firing as happened with the moccasin pipe.  It came out wonderfully.  :-)

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Most of the pit/sawdust firing I see is burnished which gives a lovely soft finish to the pots. Colours can be produced by adding oxides to the firing . Customers must be aware that the pots will not hold water. They are also fairly fragile. You might try googling Laura Wee Lay Laq and have a look at her work for burnished pieces.  Lin

I did burnish 1 of the bowls, the fluted one.  This will work ok for some things but not others that have carved detail in them, such as those feathers...

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Here is what I think you should do:

 

Dig a slight pit or use bricks to create a fence.

Put about 2 inches of wood shavings or sawdust in.

Partly bury the pieces in. The parts that are buried will turn permanently black. The tops should be grey-white-clay colored with some variations. If you add some copper (carbonate or sulfate) there will be reds in the top part as well.

Pile on wood.

Set it on fire. When it is really going, cover it with a sheet of metal.

Wait.

 

Pit fired pieces won't be vitrified. They will not have a glossy, glassy surface. They will not be sanitary by Western standards.

Your pieces will be more successful and stronger if you can get them bisque fired beforehand.

You do not need to know or control the temperatures reached.

Burnishing is done at the leather-hard working stage. It compacts the surface and gives a smoother finish. The smooth surface makes things prettier.

 

I recommend making jars. They work well in pit firings, are functional, don't need to hold water, and are not really for food.

 

And if you think making pottery is hard... the selling part is harder still.

I already have/had my pit dug but I opted to use my yard fireplace thingy yesterday because so many of these pieces are so small I was worried I might not be able to find them at the bottom of the pit in all of the ashes afterwards.  It seems to have worked out pretty well.  Kiln firing isn't an option.  I don't have access to a kiln and I doubt I would ever be able to afford to run one IF I could ever afford to buy one.  I suspect I would need to win a lottery to afford all of that, lol.

I haven't made or intended to make jars because I have no use for them and I don't see any kind of market for them locally, especially if they aren't food safe.  That was why I went with some small bowls I can use to put my finished beads and other materials in for display or storage here at home and pendant pieces. 

As for the selling part... I already have a few customers online waiting to see what I produce because they are interested in purchasing something if I am willing to ship.  (that will likely be limited to the pendant pieces due to fragility)  Selling the pottery can't be any harder than trying to sell the bead work.  ;-)

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Ok, I have an update and will include a few photos.

I got started yesterday, laid some brick inside my fire pit.  I took the 3 hr oven dried pieces out and laid them all out on the bricks, careful to make sure none of the pieces were touching each other.  I started with a small fire in the center to help make sure everything was indeed dry thoroughly (to avoid any explosions as things got hot) and after about 90 minutes of this began building the fire up gradually until I was able to lay the wood over the top of everything and get it really burning, and maintained this massive hot fire for over 6 hrs, until I had over 1 ft deep of hot coals with 1 last layer of wood on top for the night to keep it burning good all night.  It is now 27 hrs later and some of those coals are still smoldering in the center and the brick is still too hot to touch, though I was able to retrieve all of my pieces just a short while ago.  During the course of today I gradually cleared away the ash and let everything cool gradually all day, setting the pieces up on top of the ash as they cooled.  Again, this worked out nicely even though I was getting impatient to see if everything survived.  Happy to say, I only lost a few of the terra cotta feathers, which I kind of expected.

 

The fluted bowl was burnished before firing and has a very nice shiny finish on it.  I haven't cleaned anything off yet, too eager to snap a few pics first, so the photos are of the pieces before cleaning the ashes off of them.

 

I am going to attempt the ash glaze on a few pieces this week in spite of the discouragement here to do so.  After last night I am confident I can get my temps up to at least 1200 - 1300F, if not beyond.  The melting point of aluminum is 1221F and the ring of roofing aluminum I wrapped around the lower portion of the cage (to help insulate/retain heat) did start to melt, and that was on the outside of the cage, so the outer side was exposed to the air.  Last night our air temp was in the mid to upper 50's with a somewhat strong wind, and the aluminum STILL managed to start melting... so I am confident I can find a way to achieve the needed temp.  The worst that can happen is it doesn't work out and I fall back on ordering some low temp glazes online for future pieces.  As it is now, I am going to have to replace the wooden handle on the cover of my yard firing pit because it caught fire so many times last night from the heat.  I will also have to keep an eye on the steel cage that surrounds it because that made it to white hot during the course of firing last night.  I am able to get a much higher temp in the in-ground pit I dug, so will likely use that for any glaze firing. 

 

As expected, most of the pieces turned black, at least in part.  Some pieces, such as the pendants, will get painted and sealed with a clear semi gloss finish before I string them into necklaces.

 

I know I still have a huge learning curve to overcome but I am having a great time doing it and am extremely pleased that almost everything came through the firing successfully with that nice "chime" ring to each piece afterwards.  

Thank you everyone for your input.  I will post a few pics once I figure out how to get them in here, lol.  The only option I see here is for URL and I don't have an online photo storage to draw from. 

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