Thursday, April 24, 2014

A Shed Visit

This week, Peter and a group of his ceramics students from the New Brunswick College of Craft and Design made a trek over this way to visit some potters.  And they stopped to see me, too!

As my pots are just in their infant stages, they primarily asked me questions about my shed.  And I asked gobs of questions of Peter about my kiln.  (He suggested a higher/tighter bag wall and a more substantial target brick.  Okay - this I can do!)  It was a quick-ish visit, really.  But then I tagged along for the rest of their tour.

Three studios and one cafe stop later, I was chock-full of ideas, inspiration, and even a wee bit of frustration (Oh, how I envy the time these students have to spend on their pots!).  And I even got to finally meet Mr. Tim Isaac.



Who was nice enough to take hold of my camera so I could jump in, too:


Thanks (for the 80th time, I know), Peter and ladies!

Time to get to work.

Saturday, April 19, 2014

Big Anthony's Third Firing: Getting Closer!

Well.  Thanks to a well-timed phone call from Peter Thomas, who not only explained what I needed to change to achieve reduction (close the primary air), but why (no matter how many times I've read it before, it only made sense when he spelled it out for me in 15 seconds flat), and most importantly talked me down from my high level of stress that comes when I cannot get the damn thing to reduce ...

It worked!

  • The flame was much happier this time from the burners - blue and strong, with a good sound.
  • I did get the kiln to cone 6 without using a single piece of wood.
  • The firing was quite even, compared to previous efforts (range of soft cone 5 to hard cone 6).
  • I did get some reduction, albeit on one shelf.
  • I did get lovely soda, albeit on the same one shelf.  (Because I didn't clog the sprayer - finally!)

It took 16 hours or so.  (All but one piece had been fired before, so there wasn't the need for slowness at the beginning.)  This really helped, to assure my brain still worked by the end.

Marc Ward has told me it takes between five and eight firings to figure out a gas-fueled kiln.  But I've read elsewhere it takes some folks years.  Having never fired a gas kiln (besides my own two small ones) before this, or even witnessed someone else fire theirs, I'm very, very happy things are starting to look up already, after only three firings.  I credit it solely to an awful lot of help from afar.

So, here's what I need to work on:

  • The burners were maxed out hours before the cones fell.  Things were very, very, very slow at the end.  It's perfectly fine if this is the way it's always going to go, but it just makes me nervous that it won't work if the kiln is more tightly stacked, or it's less windy, or if I stand on one foot too long, etc.
  • The flame came into the kiln hard and fast, hit the bag wall, went straight up.  I had no way of seeing the flame at the top, but further down the kiln I had a hole where I could see that it was now very, very soft and licking, and it had gone over the bag wall, through one shelf, then down, under another shelf, and out the flue.  This one shelf the flame touched is the only one with any reduction, and it received most of the soda, as well.  (I'd like that soft flame to make its way throughout the entire kiln, not just one shelf.)



  • A couple of the pots (all on that one shelf) have some small cracks.
  • Reduction is still a mystery.  I'm attempting a body reduction from 1623°F to 1800°F, and I believe I was not able to achieve it this time.  Although the last few hours of the firing it was in reduction the entire time - and I couldn't make it not reduce.
  • I have to fire with the damper open only half an inch or less.  This just doesn't seem right to me.

And!  Here's what I hope will help answer these questions:
  • Peter.  He's bringing a group of his students to the area next week, to visit a handful of potters.  They're coming here first, and I have high hopes I can bribe him with cookies for some detailed kiln help.
  • Apparently I need target bricks in front of the burners.  And hopefully Peter can explain why!
  • I had very few pots on the kiln.  Partly because I figured it wasn't going to work and didn't want to ruin more pots, partly because I just don't make enough.  But packing it more evenly, and tightly, should help.

In any event, folks.  This here is what the kiln looked like when I opened it up:



This is the top back shelf, the one that saw the least soda/flame/reduction (D in drawing above).

The two creamy white pieces on the right were glaze with Malcolm Davis' shino - this is what this glaze looks like in reduction.

Next to it, the top front shelf, which did receive some soda (C):


Bottom back shelf (B):


The shelf that saw all the action (A):

The two mugs on the left were put into the kiln completely dry on the outside - no slip, glaze.  The three you can see on the right had a couple different slips on them.  Both of these slips, throughout the kiln, actually repelled soda (which was not my goal) and left some colours behind, depending on the clay body and the placement in the kiln.

Some of the better pieces, mostly from that shelf:


Yes, I'm aware the photos above aren't exactly professional.  Neither is my setup.


Although it's handy to have a banjo case hold up your light reflector thingie.  And who doesn't need an accordion in their photo studio, really?

Did a Spring Cleaning of the workshop yesterday, hoping to do the same for the kiln shed today.  Photos coming soon.

Sunday, April 13, 2014

Big Anthony's Second Firing: Day Two

Well!  That second firing didn't go so well, but - again - oh my, did I learn so much.

Basically, it stalled at 1900°F again, and I again used wood to reach temp.  I again screwed up the reduction, and I again screwed up the soda.  But this time I did not fail at cooling!  Yay for me!

After a week of fairly constant research, questions asked online ("Where opinion masquerades as fact," Marc Ward says) and of Mr. Ward, I've come 'round to the following conclusions:
  1. The brick in the flue was a very bad idea. (Here seen from the inside, as I was loading the kiln, and from the outside, looking through the chimney, during firing.)

    Will not be sticking that in there again.
  2. The Venturi layer in the stack was probably a bad idea, too, but there's nothing I can do about that now.
  3. The regulator - which I thought was non-adjustable, needed to be adjusted to allow more pressure to the burners.
  4. My bag wall sucked, and was not even really a bag wall.  It was just one brick high (4.5"), but I've now increased it to three bricks high (13.5") with some spaces throughout.

    Two of my soda ports are now on the wrong side of the bag wall. We'll see how that affects things.
  5. The chimney is, more than likely, not tall enough.  However, I cannot increase the height with more hard bricks - as the slab beneath the kiln/chimney wasn't reinforced and would crack under more weight.  After much searching, I've procured a 14" diameter, ~36" high pipe to set atop.  Husband cut off the bottom and guy wired-it to the chimney.

  6. I was using far, far, far too little water in the sprayer, which fatally clogged it up again.  I believe I've fixed it now, and understand 1. The proper ratio of water to soda; and 2. That I need to keep the solution hot between charges.
  7. I'm also doing my best to keep some space between the shelves, to help the heat circulate evenly.
As I understand, my basic issue is this:  With the tiny bag wall, the flame was coming into the kiln, jumping over the wall, and going directly out the flue - instead of what it should do, which is hit the bag wall, go up to the ceiling, and circulate down around the shelves, then go out the exit flue.  As a result, the kiln wasn't getting hot enough - all the heat was going straight out.  This was causing the stall at 1900°F.  I was firing the kiln with the damper almost completely closed, in an effort to keep the heat inside - and this made it impossible for me make the very slight adjustment then necessary to achieve reduction.

Hopefully now, with the flame coming in stronger and hitting this better (fingers crossed!) bag wall, I'll be able to fire with the damper in a better position (further open).

As it could go All Wrong again, I've decided to just fill him up with the same pots as went through the last firing.  As I can fire it faster, and the pieces are ruined already anyhow, it takes a fair amount of stress about it.

Put a fresh coat of kiln wash on the shelves yesterday.


And even got to work on one of the missing kiln shed walls.


It even has a window!  Pic to follow.

Tonight I'm readying myself mentally to fire tomorrow.  Wish me luck!

Sunday, February 23, 2014

Big Anthony's Second Firing: Day One

Friday:  Make new interior glaze sprayer thingie (as seen in previous post).  Add slip and glaze to pots.  Mix a new batch of wadding.  Make a couple hundred little balls of wadding.



Try to stay in your sticky seat if you can, while listening to an incredible playlist of, well, incredible music.



Arrange everything all perfect-like on the taped-out shelf templates.



Saturday:  Place everything, on wads, on shelves (or on other pots, on shelves).  Including a couple little saggars filled with various goodies.  This one copper wire, another a piece of charcoal, others various oxides.



The cup with the black line, front left, ended up lying on its side, atop the box.  Wadding in between box and cup.  The idea is the copper will burn in the kiln, and whatever flies up from it will land squarely on the side of that cup.  This is the idea.  The idea.



This here is a bisqued platter I made ten years ago or so, back in Illinois.  When Glen picked up Strega Nona last fall, he took this home with him.  He put it into a shallow container filled with ... um, something that rusted?  I can't remember now!  But, through osmosis, it drew the iron up (well, in this photo it would be to the right-ish) and deposited various lines all through the pot.  Along the way it also grew some mold, but nevermind that part.  We're both excited to see how it comes out of the soda kiln.



While I played in the shed, Super Husband put two new soda/wood holes in the kiln (pic in next post).  Then, because I like to do everything the difficult way (or ask others to do so), he kindly carried out the shelves - fully loaded, pots teetering on their little wads - and placed them on the wadded posts.

Then it was time to roll.  Built a quick fire in the chimney to start a draft.



Remembered at the last second to put a brick in the flue (a recommendation from the folks at Ceramic Arts Daily forums, with hopes that it will help me get past 1900°, where it stalled last time before I started adding wood).



Three-year-old stoker.



So.  Planned changes from first to second firing:
- Fire to 1100°F (through quartz conversion), slowly, on Day 1, close it up and go to bed; SLEEP; Fire to temp, quickly, on Day 2
- Put two new holes in middle of kiln, for soda/wood
- Place brick in exit flue (see above)
- Cover extra hole in damper (slot for damper is about 1/2" higher than the damper itself - just need to set brick on top of damper / in front of this hole)
- More soda
- Do not attempt to down-fire.  Just close all ports and damper as tightly as possible.

Saturday we slowly fired to 1100°F, just as planned.  Buttoned it up tightly and really did sleep (as much as you can with a three-year-old who wakes up screaming in the night because she needs to pee, then spends an hour or so lying next to you, pulling your hair, while she tries to get back to sleep).

Sunday ... Well.  That report will be here soon.

Thursday, February 20, 2014

Gearing Up

Pint o' grog, anyone?

  A friend made a straight rib, angled just so, to help me make pints.  None of these are exactly what I'm shooting for, but each one gets closer.

My six-year-old took this photo.  Glazing today!  One piece broke thus far.  Ah, the joys of raw glazing.


Now that I understand exterior slip must be applied before interior liner glaze, I had to come up with another method for applying said liner glaze.  (Because I am incapable of pouring glaze into the piece and pouring it out without dripping onto the exterior - and with the slip already there, now I can't wipe off those drips.)


Ever-Helpful Husband, upon hearing my needs and wants, declared he had a submersible pump I could use.  He even dug long enough to find the fancy valve thingie for the top.  We are hoarders, hear us roar.

Worked great in the sink with water and a trashed mug.  Took it out to the shed, and - Ayup!  It's a winner!  Works perfectly.

Phew.  (Reminds me of my way-fancy "plywood + 2x4s + junked exhaust fan" garage spray booth back in Illinois.  I've been high-society for decades, folks.)

I'd like to cut a couple/few more soda ports into the kiln before firing, but otherwise I think we're ready.  Hoping to slowly get through 1060°F on Saturday, shut it up tight for the night (and go to sleep!), then fire to temp in about 12 hours on Sunday.  Cross your fingers!

Saturday, January 18, 2014

Results of the First Firing

I had absolutely no expectations about what I'd find in the kiln.  Zero.  I had a hope - a hope for one (just one!) nice pot.  Just one thing I didn't have to turf.  But it wasn't an expectation.  Just a hope.  A little dream.  I knew already nothing had blown up (as I couldn't see shards lying about when looking through the peeps during firing), but after having screwed up the reduction, soda introduction, and cooling phase, I had no idea what I'd find.

I was so absolutely relieved when Alasdair and I snuck (I refuse to use the word "sneaked") out the next morning to open the lid.  Certainly not a load full of keepers, but absolutely a load full of answers.  Ohmyword, I can't begin to type out everything I learned from what I found in there.  But I'll share a few.

I asked Andrew to dig out and carry to the shed for me each of the four shelves full of pot'try, exactly as they were, so I could study the flow of flame/soda/ash through the pieces.  These are the bottom two shelves, and this photo is taken from what would be the fire box.  I put all the wood in from the left side of this photo.  The soda deposited itself on the front of the pieces, and left the rest either blank or flashed with orange, depending on what slip (or not) was applied to the piece, on its way out the exit flue - which would be down by that white board.

Here's the first apology:  I was far too excited (to take these off the shelves and organize them by type of slip) to properly take these photos.  But here they are, back-lit and all.  Hopefully you get the idea.

Below are the top two shelves, flame/soda came from right to left.  Missing are two pieces in the front - they were Alasdair's, and he's too busy using them to let me put them back into my photo.  All that's left of them are the three circles of alumina wadding (per piece) used to keep every pot from fusing to the shelf.

Learned:  I need more soda (but we already knew this, as much of the soda was left in the bucket and then at the bottom of the firebox).  However, it's great to see that little bit of soda was able to make its way all the way to the back shelves, both top and bottom.  Certainly thicker and hotter on the front bottom layer, of course.  And the pieces right next to the stoke hole received the most.  Perhaps a matter of draft, as I was frequently opening the hole on that side?

Okay, next apology:  I really do know how to take proper photos of pottery.  These are not they.  This is, instead, a five-minute photo-booth setup, which is missing some lights and diffusers.  Again, it hopefully gives you a general idea.

Learned:  I need to have my camera and lens professionally cleaned. (Sorry for the grey dots.)

So.  What primarily came out of the kiln was pieces with a touch of soda and perhaps a little flashing (again, flashing is the colour that shows up on the opposite side of the flame path).  Like so:


Learned:  From this piece, I can tell this particular slip flashes quite nicely, even with very little soda in the firing.  The ring at the bottom had no slip, so it's easy to tell what this little cup would have looked like (all white) had it been left dry, with no slip.

Slip, I should mention, is not a glaze.  Without the soda in the kiln, the slip would just be a dry, thin layer of basically clay.  But when the soda is introduced into the kiln, it creates its own glaze with the slips and/or clay.  (Emily Murphy describes the process succinctly here: http://potteryblog.com/2006/01/what-is-soda-firing/.)

Here's a little cylinder from the sweet spot, right in front of the wood-stoking hole.



And so is this.

Learned:  Slip must be applied before liner glaze.

All pieces need to have a regular glaze applied to the interior, as the glaze-forming soda doesn't make it all the way down inside vessels - and you need a glaze on the inside of a functional piece.  On some of these pieces, such as this one, I poured (and then poured out) glaze into the cup, let it dry, then dipped the exterior in a slip.  As you can see, where they meet, it's not happy.  It's completely logical that slip should not be applied over a glaze - it just hadn't occurred to me before that it would happen on the rim.  Very happy to learn it now instead of later, when it matters.  Next time, dip exterior in slip, then pour glaze inside.

The rest of the mug:

While it didn't get a huge amount of soda on the front, this deep orange flashing is exactly what I'm looking for.  I'm thrilled!



Mug right next to that one:

Learned:  I've never had pieces crack, in many, many years of firings.  However, this time these two mugs cracked at the handle like this.  I believe it's an issue with single-firing, perhaps too quickly during a particular stage - they were also the two closest pieces to the burners.  Will research this issue.

The rest of the mug (again, slip over glaze did not work!):


So these two mugs were right next to each other, but had different slips applied and were made with different clay bodies (um, I think).  So the result is slightly different.

Learned:  Take better notes on clay type when throwing.

Here's an example of a slip that just plain ol' didn't work.  This is one of the better pieces using this slip - the others were just dry and white.  Ew.



A number of cups were glazed, both inside and out, with a carbon-trap shino.  Which is supposed to produce results like these:  http://www.pinterest.com/ultrastructure/pottery-davis-malcolm/ I assume it's an issue with me not reducing properly, but mine turned out just a dull, flat, creamy white.  This is the only one that had any character to it whatsoever:



This fella was also right next to the firebox, but he had no slip at all (except right where the handle attached to the body).  It's lovely.

This side (below) is close to what I'm aiming for.  This "orange peel" surface.  (Click it to take a closer look.)  Except I want it to have colour to it - a nice grey, which comes from carbon in the kiln (reduction environment).  This mug needs a bit more soda, and of course carbon, but I'm very happy to see this particular clay flashes a little bit without any slip.



Here's an example of another variable (besides soda thickness, carbon in kiln, type of clay): thickness of slip.  These three pieces have the same slip applied to the exterior: on the bottle it's quite thick, poured on; and the other two pieces had thin-ish layers applied with a paintbrush.

I don't think you can tell, even in the blow-up, but this little plate has a thin, light-coloured ring, about 1/4 of the way in from the rim, of orange-peel surface.  And it's a lovely shade in person.  I intend to put a very light coating of this slip on a few pieces next time, and see how they look really loaded up with soda.

Another example of two pieces with the same slip (as each other, not the same as the ones above), but this time applied at about the same thickness.  The difference is their placement in the kiln (and, I think, the clay bodies):

Nevermind the green spots on the bottle - those came from my ink-stained hands as I set it on the backdrop.

Not really pictured here is my realization that only two of my clay bodies work for soda.  All three clays are from Tucker's Pottery:  Mid Smooth Stone, Mid White, and MCS.  The last, a porcelain, is worthless in the world of soda (at least it appears to be, from this firing).  Here are some chops (signature stamps) - the left two in porcelain, other five in ... not sure.  But in one or both of the other two clays.  Some great colours here - looking forward to putting in some dry pieces with these two clay bodies next time.




I've only listed a very small sampling of what I learned from the firing.  If I had zero expectations for usable pieces, I had very low expectations for information gleaned.  I really can't believe how much more I understand now vs. before I opened that kiln - not to mention before I fired it.

So, yes, as I went out there to open it, I kept thinking, "Oh!  Let there just be one piece.  Oh, please.  Just one!  I'll be so very happy if I just have one piece of pottery that I can keep!"

Well.

I found one.

And this is it.

That, folks, is what I'm shooting for:  An orange-peel surface with a nice, tasty grey colour to it.  Thick with texture.  Yummy.  Makes you want to run your fingers over it.  I even adore the little specks of iron, which I assume is inherent in this clay body (but could be wrong).

I'd be happier if the back were a bright orange instead of white.  But truly - that I even found this exact front surface I was looking for - on my very first attempt firing this kiln, having really no experience firing a real gas soda kiln (and truly no experience with wood), is nothing short of amazing to me.



Unfortunately I have no idea what was on the exterior of this piece (Learned: Take better notes while glazing.).  But I know it wasn't dry, as I can see some drips there on the back.  I do know it was the very first piece hit by gas, wood, and soda in the entire kiln.  Which makes me want to put about 20 holes all over the kiln to add both wood and soda from every side, at every level.

Well.  I really do have a plan to make a few small changes to the kiln, and in the firing of it, based on what came out of it.  But not too awful many.  Because I seem to be on the right track already.

Yay!

p.s. This is what happens when you shoot a long, thin, cheap piece of [what we think was] brass into a 2200° kiln:

 
Black is ash from the wood.  Blue gunk?  Soda.  Wand?  Disappeared.  So glad it ended up in the firebox.