potsblog

Wednesday, October 31, 2007

Throwing a Bowl [Not]

video
This clip took an age to load,but seemed appropriate since 2nd and 3rd year students at Tel Hai are starting their year with 300-odd bowls to be made for our annual Symposium [5th-7th Dec,guests Regina Heinz,Chris Gustin,Clive Bowen].Kiln #16 is off and cooling- I'll have to wait 'til tomorrow to see what happened.
{Thursday]- I see the clip hasn't shown up- I'll try to fix it...

Complicateder and Complicateder




As I hoped,using two programs back-to-back makes it possible to grow more rings.Now to see if we can make them even bigger...[firing #16,around 640 degrees as I write]

Monday, October 29, 2007

Bottling


The wine seemed to have stopped bubbling through its airlock,so Yahel helped me sterilise [boiling water] the bottles and equipment and siphon the young wine into 31 bottles -this year's batch. Initial tasting shows promise.
Meanwhile crystal #15 has been firing away- we just reached the peak [1260 this time] and are into the crystal growing segments of the cooling/soaking cycle. For this firing,I intend to use two separate firing programs on the kiln controller: since each program has only 8 steps,I am limited to 4 crystal 'rings' of which only 3 usually materialise on the fired piece [for reasons as yet unclear to me]- using 2 programs one after the other,I am trying to see if I can get another 3/4 rings,thereby making an already complicated process even more so. Is there a name [or treatment] for this?

Sunday, October 28, 2007

Striking Results



A couple of vases from Friday's strike fire: there was indeed a change in colour,though it's hard to say exactly what it was- the background colours are just more complicated and interesting. Kiln #14 is nearing its peak [1275 degrees]- usually the time when something interesting happens to distract me from the critical cone-judging- so I shall cease blogging and try to pay attention to the firing.

Artist at Work


Avraham came over this morning to letter some cups with platinum lustre. Look at that grip- pure artistry!

Saturday, October 27, 2007

Batia's Kiln

Word of this firing seems to have reached as far as Jerusalem,so an update is in order. The firing went well and quickly- around 8 hours to 1230 degrees. I must say that I was pleasantly surprised,the kiln having sat unfired for many years. Batia was aiming for 1200,and turned it off when the pyrometer indicted 1200,but we all know about pyrometers- they lie,and then they die. Luckily,I had put a cone7 in the kiln [it dates from the time,apparently,before there were peep-holes] so we knew how hot it got.Yes,you're right,it wasn't luck- more like common pottery sense.

Strike Fire


A batch of silver-nitrate-coloured crystal vases [from 3-4 kilns] heading for the mysterious 720 degree strike fire [mysterious because I have no idea how the chemistry works]. They're pretty nice in this state,but we're going to see if they can be made more dramatic. In fact,in keeping with the motif of excess,I'm going to fire them to 750. Yalla.

Chainsaws


Rami fixes chainsaws in Yesod Hamaala,so I took mine in for a pre-winter sharpen [cutting olive-wood is hard on a blade].

From the Salt




I think it was William Blake who said, "The path of excess leads to the road to wisdom",or words to that effect- this last salt firing being a classic example. We unloaded the kiln on Thursday [still using the old door; Sydney thinks we may have cast the new one using Motza,a local earthenware clay,instead of S-5,a Negev fireclay,which might lead to it melting at around 1250 degrees,not a temperature at which you normally want your kiln door to start melting. He also thinks that the alumina/refractory parts of the mix would counteract this,but it would be wise to proceed cautiously,so we are nursing the old door with great care]. It was a good firing- salt everywhere and aplenty,maybe a bit too much.Cone 10 was well down- maybe too far gone:I also think that there was too much wood [I only used a shopping-bag full,about 3 small scraps per salt stoke],and possibly too strong reduction. In short- just a bit too far over the edge. It might be only one of these variables [or two] but who has the patience for scientific method- I'll try to back off all round next firing and see where that gets us. Part of this mild excess is to do with [lack of] confidence in the kiln: in the past we have struggled to get to temperature,and have tended to err on the "not enough" side.Part of it is inevitable-you just don't know how far "too far" is until you've reached it.
The pictures were taken in strong late-afternoon lighting in the studio,hence shadows. You can see cone 10 in the bottom picture at the right. the lidded jar is the first lidded piece I've fired in the salt- you have to set the lid on wads in its gallery and then wad the bottom of the jar,quite a fiddly procedure.

Wednesday, October 24, 2007

Hybrid kiln



"Hybrid" seems to be a buzz-word at the moment,and I guess our salt kiln qualifies,being fired these days with gas and just a sprinkling of wood. We fired yesterday- a disquietingly smooth operation; I arrived at Sydney's around midday,cleaned up the kiln a bit,glazed inside pots with our standard Naaman clear glaze,made up some wadding,loaded the kiln,started firing around 2:20 and was all done before 11,with cone 10 down [see picture],7.5 kilos salt and some crash-cooling. I hardly had to touch the kiln from around 750 degrees,the salt went in,the rings came out,the cones bent over- all according to plan. The question is,whose plan? If a firing is problematic,I expect nothing;if it is easy,I expect trouble. Opening [if Helen lets me take the car] might be Thursday morning.

Thursday, October 18, 2007

Another Kiln

Our good neighbour Batya over the road is glaze-firing her electric kiln for the first time as we speak. Applying the same logic as the recent Noah/dove story,I'm assuming that if I don't hear from her,everything is going well. Not only is it the first firing of what used to be Ruth Shiffrin's kiln for [I think] 30-odd years,it's also Batya's first solo glaze firing ever. She's aiming for 1200 degrees- the low end of the stoneware range,cone 5/6- and was displaying appropriate signs of anticipation and excitement when we got the kiln started around one o'clock this afternoon.

Salt Fix



Arriving at Sydney's yesterday to repair the salt kiln, we both agreed that it was in better condition than either of us had thought immediately after the last wonderful fire [from which,by the way and gratifyingly,I have sold almost all the cups]- good enough for maybe one more firing with the remains of the old door. Notwithstanding,we knocked up a mold for a new one,mixed up a mix [8 part assorted refractory stuff,1 of Alumina-Calcium cement] and inserted the latter into the former. There was a bit left over to stuff up the cracks in the kiln [i.e. left of 1st picture] and cast a couple of plugs to fit into the round salting ports. Once unmolded and dried,the new door sections will have to be fired in a kiln to as high a temp. as possible before being used in the salt kiln.

Kiln #9


Just about dialled in now: everything was right 2 firings ago,but I foolishly stood some catchers on ceramic fibre bases in kiln #7,forgetting that spilled glaze eats fibre,resulting in 4 pots stuck together,then [being smart] stood one pot/catcher on another larger catcher [kiln #8],forgetting that the 2nd one was high-fired,so when the first one shrank,it toppled over [3 pots attached]. Peering into #10 [currently under way] I noticed that the kiln prop bearing the cones has fallen over,so we are back to the inscrutable pyrometer and inspired guesswork method. Never a dull moment.

Wednesday, October 10, 2007

Five Degrees



Cone 10s from last two firings- you can easily get greater differences from top to bottom in the same kiln.The first kiln [cone 10 at 1 o'clock] gave solid crystal cover-hardly any background.Second cone [4 o'clock] is just right; 3 or 3:30 would be even just righter. Second picture is the almost inevitable collateral damage from last kiln- those extra 5 degrees made the glaze run a bit more,enough to fill the catchers to overflowing [note to self- make catchers deeper next time!]

Heat Works!




This is what we're aiming for. The last change to the firing program,raising the top temp from 1270 to 1275 [both with a 10 min. soak] has done the job- maybe a tad too much,so the current kiln [#6} only has a 5 min. soak- giving just the effect I like- lots of background,with the crystals floating on the surface like water-lilies on a pond. I'll show you the cones from the last two kilns,so you can see how small the difference is...

Tuesday, October 09, 2007

Apples and Pears


That's the way we say stairs!

Rare Earth



The rare earths,it turns out,are not really that rare- just expensive. Rumour has it that they give interesting colours in crystal glazes,so I pestered a chemical company in Haifa until they sold me some praseodymium and neodymium,flung them in a crystal base glaze- and got absolutely nothing. Even after an additional "strike" firing to 720. Just that tantalising blue-ish puddle in one catcher. Whatever that means. I'll try some other oxides in the test batches,just to see if there are any fun interactions,but I think this is the end of my brief [and expensive] rare earth foray.
This was kiln #4: I am getting pretty consistent crystal growths from these firings,as I gradually increase the top temperature each firing,attempting to get more background and fewer,larger crystals. #5 is currently crash-cooling,the lid propped slightly open on a kiln-brick,having reached 1275 and soaked there for 10 minutes. I am somewhat amazed that I can write "consistent crystal growth" in a sentence- this would not have been possible for the 20-odd years that I fired the glazes in my gas kiln...

Monday, October 08, 2007

Fixing the Kiln



Here's one of the new roof sections semi-cut-out,and [second picture] another one sitting more-or-less in place [the one behind it hasn't had its arch cut yet]. I'm going to need 18 of these pieces for the roof; then I want to re-make the flue at the back of the kiln,which has become rather constricted,and a section of saggy wall. And the door.

Kiln Stripped Bare


More topless than bare,as you can see. Sydney,back from Canada,approved of my plan,which doesn't mean that it will succeed,but at least gives me the confidence to begin.Ceramic fibre [especially old,crumbly ceramic fibre] is nasty stuff,so there is much wearing of protective equipment,with consequent semi-asphyxiation,sweating,and the inevitable string of unneccessary phone calls to the studio just when you've got all the kit on and are perched up a ladder.The old sagging roof is off and bagged- I need to find out how to dispose of it safely- now to start slicing up some new fibre boards.

Friday, October 05, 2007

Jammed Biscuit 2


I had been making pots chiefly for the entertainment of holiday traffic,i.e. in a suitably leisurely fashion,but the numbers of pots still built up [it's been a long holiday period], so,with my gas kiln out of commission,I decided to fire everything in the electric kiln. The pots were all cylinders of one sort or another,and therefore lent themselves to tight packing. With the same pots in a glaze firing [they're all for crystal glazing] I can only get 6/7 in. And yes,that last cylinder was fired on its side as shown.
For those to whom it is important or relevant- I am happy to inform you that Sydney has returned from Canada