Thursday, 28 June 2012

Cup of light

This is a large porcelain mug, impressed with a doily and a wood working tool, and glazed with a dark brown glaze. When I put the lamp over the top, light leaks right through the clay. It's a shame we don't drink cups of light because this would be a really pretty way to do it.

Sunday, 24 June 2012

Paper Clay Patches

I tend to think that once I know something about ceramics, it is a thing everyone knows and is obvious. My own knowledge and experience seem routine to me, so it's always a surprise when I make a comment about a process and the people I'm talking to don't know about it. This happened quite recently with mention of paper clay patches, so I'm going to explain it here. If you already know about it and this is all obvious, you can skip this.

Clay shrinks as it dries, and it shrinks during firing. Sometimes if you are joining two bits of clay and they are at different stages in the drying process, they will pull apart as drying continues. I started using paper clay slip for joining parts because of this. The paper in the clay tempers the different shrinkage and lets the bond take place successfully. So that's a good thing, but that's not what I want to talk about. Paper clay can also be used to fill cracks and mend breaks at the greenware or bisque stages.

I'm using mugs as an example here because I happen to be making mugs, and I had some sprung handles. It's been really hard to keep the moisture content right with the heavy rains we've been having. My studio is very rustic and influenced by the weather. The timing was off with a few of these handles, so this is what happened. I love to make mugs, and I want each mug to be special to the person who uses it, so I don't mind slaking down failed mugs and trying again, but for the purpose of illustration, I'm going to show you some repairs. If you have some work you've been labouring over for months on end and it gets a crack or break, you might want to try this technique to save it rather than melt it down.

Here we see a sprung handle. The handle was a bit too dry when I put it on, and although it seemed to show enough flexibility at the time, that turned out to be just one of the sneaky tricks porcelain plays. It was too late, and when I returned the next day, the handle had cracked, and the mugs were well past leatherhard, approaching bone dry.

This clay is Valentine Clays Royale porcelain. I assume it should go without saying, but use the same paper clay as the original clay body for this sort of thing.

I worked the paper clay into the crack, making sure to get it all the way down into the bottom, then building up. Because the two edges of the crack no longer line up, I built the paper clay up over the two edges and a bit higher all around. It doesn't have to look pretty at this stage, and might even be better if it doesn't because the patch can sink down into the gap a little. The excess clay can compensate for this.

Into the bisque kiln with all the others for a normal firing. I did candle, but didn't otherwise give this a long drying time prior to firing.


In the mean time, I noticed a small crack in a pot that had just come out of the previous bisque firing. This is an occasional side effect of the way I alter my pots. Again, I might have just thrown this out, but I was thinking of you and your need to know, so went ahead with the patch.  It's made of a different clay, Valentine Clays V9G.  I didn't have any V9G paper clay on hand, so I made some up.

First I ripped up some old egg boxes. You can use any paper for this. Lots of people swear by toilet paper, and I've heard of people using computer paper or newspaper, or whatever is around, but I like egg boxes because I learned that they are an end of life recycled product. Paper can be recycled up to seven time (I have no idea how the tell how many times it has been recycled, tell me if you know), and when it's done, it gets made into egg boxes. Egg boxes cannot be further recycled, so they go into compost. Compost is a good thing, but I think it can spare me a few egg boxes. Here I have used the whole lid and half of the bottom of a 12-egg box. Don't worry about the colour, it burns out.

Add water and pulverize. It's fast. It doesn't have to soak for ages, just go ahead right away.

Next I glopped in a bunch of the squidgy V9G from the bucket of wet clay waiting to be reclaimed, then pulverized it together with the paper so it's nice and smooth and consistent throughout the batch.

Some people find a benefit in being precise in their measurements. I'm precise in glaze mixing, but I don't find it matters for this. I've heard of paper additions being anything from an iota to about 50%.

And it's good to go. Be sure to label both lid and container if you're using more than one type of clay in your studio.

Next, I work the paper clay into the crack. It could subside into the crack a little, so let it dry for a short time and then cover it with a little more. Neatness does count here because this is going to get glazed without another bisque firing. I have, in the past, reattached little broken off bits with this paper clay on bisque technique, and it's been fine. It might not always be fine, but if your piece has become un-fine without trying this, you have nothing to lose and possibly something to gain.

Back to porcelain. Bisque firing done, mug ready for further processing. I can still sort of see the line where the gap was.

I do generally go over my mugs with a sanding pad before glazing, just to make sure no little stray sharp bits are lurking on the underside of the handle or on the rim where lips might object to them. I smooth off my signature on the bottom so it doesn't stab people who hold the mug from the bottom. Reconstructive surgery takes a little more work than usual, but not vastly more. If the piece is worth it, you won't even notice the extra minutes.

I use silicon carbide embedded griddle pads, made for cleaning flat grills in restaurants. Sandpaper would do just as well, and is probably easier to find. I also use a metal tool to ping the easy bumps off.  The handle repair is just going to take a little extra rubbing with that pad. Bisqueware sands easily, paperclay bisque doubly so. It's sort of like firm chalk.

Once done, it looks much like any of my handles. The repair is not obvious unless you're really looking for it. Maybe not even then.
And now glazing. The patched mug gets the same treatment as all the others.  Can you spot it? It's one of the smaller ones.

An overnight stay in the kiln with a trip to 1300 degrees C, a day to cool, and out they come.


Let me know what you think!

Saturday, 23 June 2012

Summer Begins

It's officially summer now, and the rain occasionally lets up. Saturday gave me several consecutive hours of non-rain. Not warm, not sunny, but not rain. Plenty of wind, though. I was able to set up outdoors for some super-splashy glazing of the sort I avoid doing in the studio when wet work is around. And wet work is around because it rains all the time and nothing ever dries.

But now the sliding blocks have done some sliding. I glazed enough mugs and plates for two kiln loads, which ought to keep the kiln working until the wet work is bone dry, and can be bisque fired. After that, I can do glazing in the studio and not have to worry about harming work in progress.

Two weeks until my first day of Cambridge Open Studions 2012, and things are finally moving. And it's raining again, but that's all right.

If you got some not-rain today, I hope you enjoyed it as much as I did.

Monday, 11 June 2012

Thanks, nature!

No images this time, I don't have anything at an interesting stage to show. There is a lot in the works, though, and in time I will share it with you.  This is just a bit of a Monday morning ramble.

I think we all know clay comes from nature, but at my house, nature doesn't stop casting its vote until quite late in the process. 

We've had a lot of rain this year. I'm not talking about warm and lovely raindrops falling on hot pavement, I'm talking about cold, muddy, windy weather that is always wet. My shoes are always wet. My dog is always wet. This changes the way I would have been working about now. In a normal year, I would have had the door to my tiny studio open to the back garden. Cats, a dog, and a boy child would have been wandering in and out, blissfully saying hello and checking on my progress before wandering away to do their own things again. But no. The door stays shut. I am acutely aware of the rain and wind doing their thing a few feet away because my studio door has big gaps above and below it, and even between some of the boards that make it up.  We are still on winter process here. Nothing ever dries without artificially provided heat. I have to have the heat on in the studio, not for my own comfort (although I do quite like comfort), but for the functional purpose of getting work to leatherhard so it can be trimmed and altered.

Dave the Husband Creature hates that. He does not like to pay for heating. He has installed a program on his computer that monitors our electric usage. He knows when I have the heat on. He knows when I fire the kiln.

I got a new kiln from Northern Kilns last year. It's smart and peppy. It has a programmable controller. I set one of the programs to "candle kiln," which heats at the rate of 10c an hour up to 110c, which slowly drives the moisture out of the nearly dry pots. I think of this as my 95 litre summer.  This is a vast improvement over my previous kilns which had minimal controls and considered any settings to be vague suggestions from a dottering old aunt.

My first kiln is at least as old as I am and has a simple 1-2-3 function. It takes a long time, but does a nice bisque firing. The lid weighs a ton, give or take, so I have to plant both feet firmly and open/close it with Olympic weightlifter moves. It will chug along happily at 1 or 2 or 3 until I tell it to do something different by turning the dial. It has no pyrometer and no thermocouple. I fire by eye. I can see when the air inside is orange. Not just the pots, the air has to be orange. Then I turn it off at the wall. I got it from an advert in Ad Trader when I first moved here.

My second kiln is rated to 1200c, which isn't really enough. I fire to 1300c in glaze firings. I do a little low fire work sometimes, so it could be good for that, but I really wasn't doing enough of it to justify having a whole kiln for it. Again, it's a 1-2-3 dial controlled thing, but at least has a thermocouple and temperature gauge, and allegedly shuts off when it reaches the temperature it's set to. Dave the Husband Creature is good with electricity, so he reverse wired it for me. He made it so that rather than have the controller stop the kiln when it gets to a certain mark, it will continue to fire while it is above the certain mark. I wholeheartedly recommend that you do NOT do this. Not only do fire bricks become conductive of electricity at a temperature higher than they are rated for, but it cracks the bricks. That kiln, my only front-loader, is another Ad Trader acquisition. We bought it from a woman whose husband had run off to Australia with some hussy, and she wanted her garage space back.

My third kiln (RIP) was a round top loader. It had a controller. I could control how fast it got hot by percentages. I could tell it when to turn off, and it would. It was like magic. Alas, it was not really meant for what I wanted it for, and over the course of 10 years I managed to kill it dead. It stopped being consistent with its percentages. It stopped turning off when it was supposed to. Its lid rusted to bits -- bits that had to be swept up, an unsavoury mix of rust chunks and crumbled ceramic fibre. It already had a lot of rust when I got it, and it was not shy about continuing to rust. Dave (tHC) made me a new lid from fire bricks. Heavy to lift, but not as bad as the first kiln's lid. Its banded together sides got loose and rickety. The floor fell out, so I put the whole thing up on a bed of fire bricks. I had to stay up all night or wake up at intervals to do a firing because the kiln no longer did what I said. And of course electricity costs less in the wee hours.  You get the picture. That kiln came from a local artist when he moved away from sculpture to focus exclusively on painting. I did get an awful lot of use out of it, though. I think it's decidedly beyond salvage now, except perhaps the bricks.

So the new kiln was quite a luxury.  So worth it.  It does what I say. I program in what I would like it to do, and it just does it. After so many years of seat of the pants firings, this almost feels like cheating. Close the lid, turn on the power, select the program, press the button -- BOOP! --, come back the next day. No more seat of the pants. I got it when a relative died and left me a tiny amount of money, just enough for a new kiln. I exchanged emails with Northern a few times, and then had my kiln a few days later. It was magic. I scavenged so many old and broken down kilns, I never thought I would buy a new one. Dragging home other people's obsolete dreams is a great way to save thousands of pounds, and I have a live-in sparky to beat life back into them for me. But you know, the struggle just got to be too much, and I suddenly had that little bit of money to either fritter away or do something meaningful with, so I went for the new one. And now I have a reliable 95 litre summer available to me.

As I type, the kiln is cooling from a bisque firing, and the studio shelves are full of mug bodies. I need to trim, alter, and put handles on them later today. I left the heat off so they might still be quite wet, but they're porcelain, which dries out quickly anyway. I have a lot to do, but you don't need to see more images of work in progress. I will save the camera for finished work in a few days.

I am resisting going out to the studio because it is cold and raining, but weather made clay and weather still gets a vote on how things go for it. The Met office says our rain today is at a warning level, but it's been raining for so long that I don't know it will make a lot of difference. We've been living in intermittent floodings with a side of drought warning for months now.

But yesterday was great. I had forgotten how helpful nature can be if it wants to. I had some work which was resisting drying despite my space heater. I considered putting in the house oven, but since it was emphatically NOT raining and the sky was conspicuously blue, I put the pots outside. They were actually ready for final processing inside two hours. Thanks, Nature!

Monday, 4 June 2012


 I know this will be a lot more interesting once the pieces come out of the glaze firing, but this is where we are, and I am in a sharing mood.
The first doily face plate got its foot ring and had the doily lifted out.

Sorry Tudors, I know we're not so very different but I just have to alter mugs unless they are explicitly for you. Which these are not. 

While I did the feet, altering, and handles on the mugs, one more plate got nearly hard enough to trim. I shouldn't have pushed it. I'll leave the others for tomorrow.

Alas, it is cooler than it ought to be and also rainier than it ought to be, so I have to use the heater in the studio if I want anything to dry at all. This is not the June I was expecting. But it'll work out.

Sunday, 3 June 2012

Chugging right along

 Continuing with various clay activities, I had a glaze firing. The face plates are still V9G. The one with the green on the faces is going to get flowery decals on it, and the green will help with the gardeny camouflage look. The people are made of Earthstone 50 - Crank, and are unglazed.  The small plates are small indeed, probably only 5 or so inches across.

These just have a clear glaze, and will get decals on them.

This plate is growing on me. It's got a matte base glaze with shiny green streaks on the faces. 

The people mostly stay buff, but sometimes go a bit toasty on their extremities. There's no planning for it, the kiln decides. 

Back to wet work, I am doing a small batch of face plates with lace doilies pressed into the middles. 

I'm going to leave the doilies on until the feet are trimmed, then I'll lift them out and wash them, ready to be used again.  I get these from RETRoVERT, who source quality vintage items from around the county.  Someone's Nana made these, and they ended up in boot sales or charity shops. I immortalize the work of the Nanas here. 

Mugs. There have to be mugs. I will trim, alter, and handle these in the next day or two. I don't like to make them the same.  I like each one to be its own special beverage event venue.

I think I might do a little more work in V9G, then do a studio scrub-down for the switch to porcelain.