Four Inch Bowls, Step 7. Glaze Firing.

So, the day has come. Your four inch bowl is ready for a proper firing, not just a ponsy low temperature bisquit firing.

This depends on your kiln of course. At Winchcombe we fire with wood and take it up to cone 10. The pyrometer read 1245 degrees when we closed it up in the last firing. Pyrometers are a guide but the cones are what you really need to pay attention to. This is difficult when they blow up or fall over as almost all of them did in this firing. Next time I will be making the cone packs more carefully!

The ideal for this kiln is to have cone 10 down, 11 bending and 12 tipping over a touch. When you have closed up the kiln the cones tend to move a little more.

Pictures from our firing earlier this week:

Packed and ready to be bricked up.

Close up of the cone pack before it blew up!

Smoke out the chimney, pallet full of wood ready for the second half of the firing.

Lower from spy hole.

Back firebox. Warm.

Pyrometer reading 1168 degrees.

Matt checking the top back spy hole. Reduction flame making the mask a necessity.

Matt cool as a cucumber, smoking despite the clouds of black smoke all around

"Hot rings, get your hot rings!"

Matt passing down test rings from the top back of the kiln to John.

John with Nenya and Vilya, the three Elvish Rings of power.

The firing gods sent us a messenger towards the end of the firing... a tiny mouse, eating a dry leaf.

 Once the top temperature is reached you have to block up the flue, close the fireboxes and wait. Ideally you want to let the kiln cool as slowly as possible-at least 2 days. This waiting time is probably the hardest part of the process.

Mike Sanderson who writes an extensive and most excellent website on pots of all sorts, Ceramike came on firing day. He has put up a set of pictures of the day including one of the lovely little mouse. Here's the link:

http://ceramike.com/WinchcombeFiring2013/WinchFiring2013.asp

Four Inch Bowls, Step 6. Glazing.

Your four inch bowl is nearly a finished article!

Once your pots have been bisquited you can glaze them. You want to do this at least the day before a glaze firing.

It is a good idea to sieve your glazes before using them. I did this a week or so ago to all the glazes. 

Stir it up! John Forster likes to get his hand all the way in the bucket and stir by hand. This has the advantage that you get to feel how settled the mix is, but the disadvantage of a thoroughly coated arm.

Dip your jug in this mix.

And pour it in.

You don't need to go this high, I was etting carried away.

Swirl the glaze around the bowl to cover the slip line.

It does not matter if you drip a bit.

Pour out.

Quickly sponge off the excess.

Place to one side to dry out. It only takes a few minutes until the glaze has been sucked dry.

Using a razor blade carefully slice a crisp line in the glaze.

Use the corner of a sponge to clean off any excess glaze above the razor line.

Stack them up ready for the kiln!

Here is the video to accompany this process (it is actually the right way up to start with):

Four Inch Bowls, Step 5. Bisquit firing.

This post is a birthday edition! I am 24 today! My presents have included an apron with mushrooms on it, a loaf of bread, some underwear (I was in desperate need), a couple of books and lots of chocolate. And Lauren cooked us a wonderful dinner of grilled salmon (marinated in soy sauce, mustard and lemon juice) with lentils, corn and roasted tomatoes. Accompanied by a Kiwi Pinot Noir. Mmmm mmm mmmm.

But this is about step 5, bisquit firing. This stage depends on your kiln. The principle is essentially the same whatever kiln you have though. It is a low temperature firing which serves to drive most of the water out of your pots and make them easier to handle (stronger) when glazing.

Pots going into the bisquit kiln are very fragile. Mike Finch told me to treat them like eggs.

Here is a picture of the gas kiln at Winchcombe about two thirds stacked:

Each shelf has three supports running from top to bottom.

It depends on your kiln but this process should not take more than twelve hours. Try to let the kiln cool slowly and not be tempted to crack it prematurely.  Loading and unloading are pretty easy, you just have to be extra careful not to knock the whole stack over by catching a shelf on your clothes or some such.

As there is no glaze involved you can have your pots touching any which way you like. It is best not to put too much pressure on any one point but within reason pots an be stacked densly and high. Bowls inside bowls inside bowls! Here's a tower of my four inchers:

These ones were fresh out of the bisquit kiln. You can see the clay has changed to a pinkish white.

 Once they are out of the kiln you can move on to step 6 whenever time allows.
 

Four Inch Bowls, Step 4. Slipping and combing.

Once the bowls are trimmed you let the sit out for a while again. You do not want any white to be showing on the clay, that means they are getting on for being too dry to slip. Slip is basically watered down clay with an added colorant.

These bowls are being slipped with a blue slip. It looks grey now but will transform in the glaze firing. The blue comes from cobalt oxide.

Find a bucket full of slip.

The ladle is for stiring only! Don't be tempted to drink it. It is not soup.

I like to attach a bisqued pot to the wheel in order to make combing easier.

Pour your slip in.

Like so.

Swish or swirl around the slip until it reaches just under the rim.

Tip the slip back into the jug. This naturally stirs it up and saves you going in the bucket again.

Several shakes are necessary to make sure all the excess slip drips out.

Wipe the rim with a sponge.

Place it down to dry out a little. You don't want to comb it until the sheen has gone off.

I always slip two so as to let the first go off and save time.

Putting in the top line, just underneath the rim.

A double line in the base of the bowl.

My tool for this process; a cut up membership card from the picturehouse in Norwich.

Ready for the wavy Winchcombe lines.

Wheel turning slowly, hand moving up and down.

Combing in action.

My combing tool: a cut up rubber kidney.

It is quite difficult to join up the waves but I managed it on this one.

Now place on a board and get on with the next one.

Here is the video to accompany Step 4:

Tips:
* It is important to get yourself set up before you begin. Always mix the glaze properly. Stir it up! Be sure to think of Bob Marley as you do it.
* The consistency of your slip should be something like single cream.
* If you mess up the combing it is no use pouring slip over it and trying again. It will show. As will any fingerprints or bits of slip you haven't cleaned off properly.
* A bendy tool for combing is much better than a stiff one.

Four Inch Bowls, Step 3. Trimming.

A lot of people call this process turning. I have tried to use this as a term but trimming seems so much more appropriate. You are removing the excess clay on the base of the pot to tidy it up and ensure it sits properly. The bases should be leather hard at this stage. Again the time will vary upon air conditions so keep an eye on the pots; prod them every now and then to see!

First thing to do is throw a pad of clay.

Centre a handful of clay.

Compress the clay with a slow karate chop motion.

Pull out and press down with your finger tips

Finish the pad by flattening it with a stick/wooden tool.

Tear off a square of plastic, or even better thin wrapping paper.

Place it over the pad and rip off stray bits. Some people do not do this but it helps keep the rims clean.

Centre the pot and lightly press it down onto the pad.

Use a tiny piece of plastic (old credit card) as a resting position for your finger.

The plastic helps you avoid damaging the base with your finger/nail.

Start trimming! It is quite easy if your set up is correct.

If the clay is leather hard then you should see nice ribbons of clay stream off the pot.

You can trim all the way to the rim, or not, depending. The shape should be almost there from the throwing anyway.

When the sides are done think about the base. Sometimes the cut from the wire is clean enough to warrant no further attention.

This one was a little bumpy so I used a sponge to finish it. You don't have to do this.

Final touch is taking off the bottom edge. This is the band to be stamped.

The Winchcombe stamp.

Make sure to put it on the right way.

The trimmed article!

Other tips on trimming:
* Keep your tool sharp.
* Trim when the clay is ready; doing it too early or late can prove frustrating.

Here is the video to go along with this set of pictures:

Now leave the pots to rest a while longer till Step 4.

Four Inch Bowls, Step 2. Flipping.

Four inch bowls are not just a two or three minute creation. The throwing is merely part one of this seven part epic. Step 2 takes place an indeterminable space of time after the throwing. The bowls need to sit around for a while. It is important to let them relax back for a couple of days or more, until they have wilted like spinach hitting a hot pan.

The bowls shrink in size as water escapes. You have to keep an eye on them. Not in case they run away but because you never know how quickly they will dry out. It depends where you leave them. Pots in England take longer to reach Step Two than pots in L.A.

This may not seem like the most exciting step but it is a necessity. You need to look out for the moment when the rim will be able to take the act of turning it over. You can test it by lightly touching it. It should not be tacky to the touch. To get it off the board you twist gently and lift up. If you use a twisted wire to remove the bowl from the wheel then they lift off easier.

Step 2. Thrilling stuff.

Tomorrow I will post Step 3. The bowls should be ready by then. How exciting to be writing this as it happens. Its like live TV but a lot slower and more boring.