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Second crystal firing

 
I spared you all the details of the firing this time- partly because everything happened too quickly.I thought that I would be writing a piece this morning on 'breaking the vessels',an important teaching in Kabbalah and a practice used by potters who mess up kilns:I could see that the bottom of the kiln was too hot,and,concommitently,that there was a whiff of reduction at the top- both signs of a failed firing.Opening the kiln this morning,however,revealed a beautiful crop of crystals,which I have just spent an hour or so grinding off their bases.I am slightly flabbergasted by the results,and am off to lie down in a darkened room for a while. 

Two dishes

 
Not a bad firing at all.Which means,first of all,minimal damage to kiln and pots [always the first thing I look for in a newly-opened kiln]- that cone-bearing structure survived,and the glaze on the large vase didn't,as I had feared,overflow its catcher and weld to the shelf [in fact that large vase ran less than its smaller brothers,an example of the distance between our fears and reality].The kiln was pretty even,another big surprise,and fired without,as far as I can make out,any reduction- an achievement.I lost 4 pots trying to separate them from their bases [impatience- even if they're totally fused to their base,the diamond disc gets them off].There's definite evidence that the crystals are still reacting at 1020degs,as I suspected- in fact,looking closely at the pots,I think that the crystal growth at lower temperatures is smoother,and shall try to incorporate this in next fire [Tuesday?].As I thought,the gas tank is down to 12%,so gritted teeth and ordered refill this morning.All the [25]pots got a good fire,all grew crystals,all [after session with the disc,protected with earplugs,mask and safety glasses] have clean bottoms,and a few had the sort of crystal growth that I'm looking for.Off we go to glaze and load the next candidate. 

Winding down

The pyrometer reads 1036 and dropping.As far as I know,crystals stop growing at around 1060- the glaze being thereafter too sticky to let them expand- but this glaze is so runny that I'm trying a few extra temperature twiddles down to 1020,just to see what happens:if the glaze is runny enough,we might get some "annular" rings round the edges of the crystals.Gas pressure seems low-I must check the tank level.It's enough for these low-temperature frolics,but probably not enough for the next firing.I shudder to think what the next gas bill will be.

Dance of the Crystals

For those not familiar with macrocrystaline glazes [there may be a few of you,I suppose]:the glaze is made up with far too much zinc [and not enough alumina to hold it together];it all melts at its top temperature,but,when held at a slightly lower temperature,the zinc starts to crystalize out of the still-runny glaze.Easy,right?
I've finished the firing cycle proper and am now at 1120,the upper edge of the crystalization band,aiming to drop down to 1116 and stay there for half an hour or so...

Conefall

 
Health warning- only look at this picture through darkened lenses![not really]:cone 7 on its way down at around 1220 degs.If you blow on the picture,you can see cone 9 thinking about making a move at the back [I'm kidding you again] 

The Plunge

Lit the kiln late last night;by morning it had reached 300,now it's up to 1150,still churning out a steady 100 degs. an hour,so another hour or so should bring us up to temperature.I need to pay close attention at this stage that the high gas pressure doesn't cause the kiln to slip over into reduction,which the crystals don't like at all.Firing the kiln is my main occupation today,requiring full attention,so I'll spend the rest of my time cleaning around the studio and glazing for the next kiln.
A mouse seems to have got in the kiln and eaten or carried off my cone 9 [perched at the top of the kiln] [although,puzzlingly,it left cone 7],leaving small pieces of evidence on the bottom shelf.I hope it escaped before the start of the firing...

More like it

 

This,from the third test firing a few days ago,is more-or-less what I'm trying to get these glazes to do- well-developed crystals floating against a background.At this point I decided to go ahead and glaze a kilnsworth. 

Loaded

 










No,it's not the distorting effect of some fancy camera lens-everything in the picture is really leaning every which way [Sydney,passing through the studio,raised an expressive eyebrow and indicated that it's time to replace the kiln.As if I didn't know.]For the inquisitive:that precarious structure of kiln-props front right is what I had to do,having decided to put the large vase in that space,to get two cones up to the height of the spy-hole.I wish I could tell you that it's more stable than it looks.The bottom of the kiln is empty and blocked off in a possibly vain attempt to even up the temperature distribution.The sagging roof is actually supported by a strategic prop -but what's supporting that prop?Faith and Prayer,mainly. 

Ready to go

The first in this sieries of crystal kilns is loaded and awaiting firing:I haven't yet decided whether to leave it on a low flame overnight and hope to get the firing finished by 4 tomorrow afternoon,when Shabbat begins,or fire it at more leisure on Sunday.Young Sydney passed by this morning- we're aiming for next Thursday for our next salt firing.He also informed me that our olive oil is ready- the best I have ever tasted,from a friend of his in Sde Eliezer.Convenient,as I squeezed the last litre out of last year's yellow jerrycan [avoiding the gloop at the bottom] this very afternoon.The kiln took a long time to glaze,even though everything is either dipped or poured,which should make it quicker.All the shallow dishes have a [hopefully] non-drip version of the glaze on the outside and crystal glaze inside,which takes time to do;all the sticking-of-pots-to-catching-stands adds to the fun,and,with either tall [vase] or flat [dish] shapes,planning the internal layout of the kiln [for an oxidising firing,an additional challenge in a gas kiln]was also quite a story.As usual,I have absolutely no idea if I got the setup even approximately right.Place your bets.

Today's haul

 

Getting nearer... 

Stones

 

When we first came to Safed,you had to pay someone to cart away surplus stones:nowadays they cost 7-8 shekels each.A local builder is carrying off this haul,thereby unblocking a narrow alley that leads to my studio.The third test kiln [with coloured glazes] is currently at 850 degrees and rising. 

Shabbat Shalom!

 
 

Round 2

 

Well,round 3 to be exact:fired these three pots to about 1210 [cone 7 starting to bend] this morning to check cool end of glaze melt,but saw while kiln cooling that glaze hadn't melted,so raced back up to 1245 [cone 7 down,9 just starting.Yes,I ran out of cone 8.],which gave this crop of crystals.The glazes seem to be working well,still some tweaking to be done with crystalisation temps,next step is to mix up some coloured versions and test them- also the non-runny [crystal-less] version of the glaze that I'm starting to use on the outsides of dishes- then glaze a gas-kiln's worth and take the plunge. 

 

Here are two of the test pieces- supposedly far too cold,super-crash cooled;still grew some crystals,though:go figure.Off to archery,another field where my ignorance far outstrips my knowledge. 

Nearly done...

 

New element in place [there are times when the Prussian ancestry pays off,such as in the Keeping of Spares]- now to hook it up and see if it works... 

Fixing the kiln...

 

Could this be the source of our problem? 

Testkiln

 
 

Off we go

First test-kiln (small,electric) rocketting up at around 450 degs./hr,1170 as I write,containing 4 test pieces- a white and a blue version of old and new batches of the 'new' [frit-based] crystal glaze.The whole firing [incl. 2hrs crystal-growing time] should be over by one o'clock- I tend to crash-cool the pots by opening the kiln-lid wide and standing well back [the pots only crack if I lift them out of the kiln too soon] although this is not recommended technique.Yesterday managed to snap off pyrometer tip transferring it from the gas kiln to the electric;luckily salvaged an intact tube from an otherwise-damaged pyrometer,but feel I have broken rather too many pyrometers in my 30 years in the profession- usually while moving them from one kiln to another.
Cone 7 [1230-ish] is starting to bend with 1260 on the pyrometer [you would expect higher readings because of the v.fast firing]
...and just as I write this,the temperature starts to dip...we've been here before,too-quick check on thermostat is O.K.,so that probably indicates a kiln element giving up the ghost [do I still have a spare one?] and that's the end of the firing,thank you very much.Rocketting up indeed.

Wine and other news

Yesterday,with God and Gilad's help,brought batch #1 of this year's wine to bottle;initial trial swigs indicate great saki-like smoothness concealing,one hopes,sufficient deceptive grunt.Of course,not containing even a whiff of nasty sulphurous substances,the wine seems clean and straightforward,which I tend to like.Now I have to run around for another 30-or-so empty bottles for batch#2,and maybe the kiddush-wine batch,still unbottled from 2004,and,when last sampled,coming along nicely,thank you.
Those stacked shallow dishes I asked you about last week all survived their bisc,I am pleased to say,thus adding to our store of ceramic knowledge.Past performance,as the investment brochures point out,is no indication of future outcome,so I'm going to mix up a huge bucket of one of Peter Ilsley's crystal glazes,and another of my old version,and plunge,for the next week or two,into the slippery chaotic world of high-temperature crystal growth.

Ladies and Gentlemen-the Third Temple

And the big news is-it's a prefab! (Of course,if you read Ezekiel,you already knew that).
Not many people know about Safed's thriving building-third-temples industry:this is the third third temple to have been put together in Safed in recent years.I believe the first can be seen in Jerusalem (fair enough),the second may have left the country,but this one is rumoured to be staying in Safed.And about time,no? 

Mary throwing a bowl for Chanukah's Symposium

 

Whites

Can I write here? There's been a slight technological update in Picassa,the (free and excellent) image handling program,hence recent slight glitches.All part of the creative fun.
Loaded dishes into bisc kiln this morning,having lit woodstove (last year's wood,nice and dry) downstairs,and parafin stove in the studio (this year's parafin,at this year's high prices),both for the first time this Autumn,in response to rain squalls that are starting to loosen the leaves on the vine;one dish had cracked over the foot-ring while drying,a reminder of 1)importance of throwing/fettling technique,2)importance of careful drying,3)transcience of all things,4)persistence of existence (as I break the dish up into the recycling bowl-that's it in pic #1,top left),5)mental preparation for more cracks/warps/surprises inevitably to come;this is porcelain,after all.The last picture (bottom row right) is sort-of a question to you (potters) and to myself-Is it O.K. to bisc this many dishes one inside the other?Years ago,after cracking problems with dinner-plates,I took to firing no more than three plates in a stack,whether as here or "boxed";maybe the time has come to review this practice- I fire biscs more slowly these days- particularly above 500 degs.,where I used to be inclined to bang the kiln on "full" 'til the end.We shall see.
We're reading the 2nd section of Bereshit/Genesis this week:I always have a slight sympathy with those guys building the Tower of Babel- 'one people with one language' (an admirable state,no?)- they've just dicovered how to fire bricks,and now they want to see what they can do with their new technology (you can obviously build a whole lot higher with fired brick than with the old sun-dried stuff,which must have been massively exciting).The craftsmen say,"let's start building a tower and see how for we can get"-then the politicians show up,and this great site-specific sculpture project goes seriously off the rails- I'm sure you've been there;I certainly have.On the other hand,Noach,the lone craftsman,builds his boat-sculpture (intended purely as a social protest/statement)to mass popular disinterest and scorn,takes years to get it right,and then,totally and rightfully vindicated,manages,with God's help,to survive using his craft (sic),surely a deep message to all of us.
Shabat Shalom!

From the Shalem's wedding- Mazal Tov!

Finally! Last Thursday's missing target

Here's one of the stand/trough affairs not required by these flat dishes (but essential for all other crystal-glaze pieces)

Interior of trimmed dish,with bulgey (convex) centre- happy marriage of technical ineptitude and post-facto design

Here's the trimmed base with its artful dip in the centre...

Two flat dishes perched one-atop-the -other,illustrating pronounced bowing

Memories are made of this

This being porcelain.Not surprising that God chose clay to fashion Man,if you ask me,rather than,say,starting with a monkey and trying to improve the model.Clay -and especially porcelain- already has a ferocious memory (quite apart from its ability to take an impression and therefore generate copies of itself,an early attempt at reproduction in the mineral world).I have been making a sieries of flat porcelain dishes for the forthcoming crystal-glaze ordeal:they are quite challenging technically,while being at the same time relatively quick to make once you get the hang (literally) of it;in my kiln,where I can't really use the bottom quarter if I want even heat in oxidised firings,they (being flat) give me just the right height of shelf,together with taller pots on top,to fill the kiln;also,being flat,so the eye doesn't see the outside of the dish,I can use a non-crystal-producing version of the glaze on the outside,which has the great advantage of not needing a stand-and-trough (see pic);the relatively-flat inner surface is a good canvas for crystal growth,and,by no means the least of their attraction- they sell well.
However...(and this took me a while to figure,being somewhat slow-witted and easily-distracted) when you take them semi-dry off the batts on which they are thrown and turn them upside-down to dry prior to trimming,as taught in the books,their bases proceed to bow out in an alarming fashion,remembering the downward hollowing pressure used by the heel of the left hand in their making.Since I don't leave too much thickness in the base,not wanting a particularly high foot,this led to the premature demise of quite a few pots as I tried to trim level the bowed base prior to cutting a foot.The solution,and consequent design feature,seems to be firstly (and gingerly) to push the domed untrimmed base back down with a firm kidney,then,having cut a standard rounded base,to push the still-dangerously-low middle section of the base down (again the kidney,again gingerly) until it is concave.Not only does this give the base profile an interesting variation,but it also forms a small convex island at the centre of the bowl itself,which,I hope,will prevent the runny crystal glaze pooling too much in the firing;if it makes some potter think "how/why did he make that bump in the middle of the bowl?" so much the better.
Is this at all clear?I shall now attempt to post some pictures to illustrate,each being worth a thousand words.And then back to work,there being still half-a-dozen more to trim,and another batch of larger bowls to make.We are promised rain,but most of the leaves are still on the vine,indicating that Winter is still a while off.