Friday, November 1, 2013

Words, crystals, fuming, lessons, and a pardon!

Words, there is a plastic quality to them. Like soft clay, words are imprinted by the fingers of the hands that hold them.

Ha, that opening paragraph sent me on a little journey of my own, and I have spent the last 40 minutes writing short monologues, then erasing them! In fact, even the first paragraph has been lopped and pruned! Maybe this is a reflection of the time of day. I started this a few minutes after 5 in the morning, and there is a delightful quality to that hour when sleep still lingers, and birds are coming into song, and even the air seems to inhale and exhale, stretch and stamp its feet.

I have a new load of pots in the electric kiln that are nearly two thirds of their way on their journey towards 1260 degrees Celsius (2300 F), and I have a flutter of excitement about these ones, because I had some interesting results from the last test firing that I did, and feel like I may have found some new territory to explore.

When glazes are very hot, some glaze ingredients produce gas, or become volatile. This means that, even in the relative clinical calm of an electric kiln, there are changes to the atmosphere, and fumes from a glaze on a pot in one part of the kiln can potentially have an effect on a pot that is nearby. I have rarely noticed this, but in my last firing, pots that were placed near something that had a glaze that contained only 0.5 percent of chromium oxide in it, were affected by the chromium vapours.

These are two views of the same pot. This pot has a glaze that contains almost 20 percent zinc oxide. The light brown area on one side of it is caused by chromium fumes from a pot that was close to it in the kiln. Whilst the brown area has messed this pot up in some respects, I am very pleased that it happened. It alerts me to a potential problem that can occur when such a pot is placed near something that contains even a small trace of chromium oxide. It also alerts me to an effect that might be used creatively in the future.

Small amounts of chromium can turn white glazes, that are opacified with tin oxide, pink; and chrome and zinc oxide together tend to make various shades of brown. Just like the words, that can mean different things to different people, this property of chromium can be really useful, or a curse that can ruin a firing! When you think about it, many of the art glazes that studio potters use are glazes that would be considered as faulty by the dinnerware industry. Crazing, crawling, pinholing, runs and crystals are all glaze faults that become wonderful gifts when used creatively! How like humanity that is... Do we really like "perfect" people, or is it those who are a bit battered and flawed that are in fact the most delightful, inspiring and loveable??!

One other thing about the pot above is that this was a refiring of a pot that was missing a small area of glaze low down. On the first firing the pot had exactly the same glaze as this one below left, that you have seen on an earlier post.

When fired a second time this glaze has still retained the sprinkling of gold coloured crystals, but the surrounding colour has shifted from shades of grey to pale green. Refiring crystalline glazes almost always dramatically changes the appearance of the glaze, it can be better or much worse! This is one glaze that I will do some deliberate refirings of, as I really like the way the gold crystals show up against the pale green.

Where things start to get exciting are when both "problem" glazes are used together on the same pot. In this test example below I have glazed the top half of the pot with my chrome red glaze, and I have glazed the lower half of the pot with the crystalline glaze that is on the pot above. I have overlapped the two glazes by about 1 inch. Where the chrome red glaze is thin, or there is little overlap, the crystalline glaze has still managed to form a few crystals, and where there is more of the chrome red glaze going into the mix, then there are purple runs. In all areas, the influence of chrome has caused the brown colour, but is not a "dead" brown, the glaze almost appears to have a lustre and it is wonderfully complex.

I am exploring these effects further in the firing that is in the kiln as I write.

In my post of 14 October I showed a photo of two pots and a hammer! These were crystalline glazed pots that had failed to grow crystals on their first glaze firing. I gave them a reprieve from "death row" and fired them again.

The green one now has some pretty little crystals, and the other failed again in the crystal department, but developed a very nice pattern, rather like the textures that you see on a sandy beach, so I will let both offenders off with a warning. All going well both will be deported from my studio before too long if I can find a country willing to take them!

Probably my favorite pot from the last firing is this one, but it has also proved to be difficult to photograph. In this photo the pot appears too light, where as in reality there is a brooding, smoky depth of colour.

In addition to the gold coloured primary crystals, there are numerous tiny secondary ones.

By-the-way, here is a photo of the beach. I thought that some of you would like it to remind you of spring sunshine!

Must dash now and check the kiln again. Lots more to write about, so I will probably do some quick posts to help catch up.

Kind Thoughts, P.


srgb said...

Hi Peter
Firstly thanks for the comment you left on my blog, I intend to post another photo when the lacquer has been applied I hope it will bring out the colours as there is a bit of red deep in those corners.
Now talking of red I think the red pot you are holding with the brown lower half is superb, I could see myself owning that one, and those gold crystals are delightful too.
Good to see you firing on all engines once more.

Peter said...

Hi Bob,
Good to hear from you. The photos of the red pot probably flatter it a little (although I haven't "tweaked" them). The red pot is one of those ones that has to be held or viewed from low down to see the interesting lower half at its best. I will be opening the kiln today and seeing what the next firing has brought me. Some of the pots in it have the same two glazes as the red pot, and I am experimenting further with the effect of overlapping them.

Arkansas Patti said...

I am so glad you spared the hammer. I think they responded quite nicely to the stay of execution.
That red pot is just stunning. Wow.

Peter said...

I'm glad I was merciful! Mind you, I suspect that the hammer might have frightened them into producing crystals!
Unloaded more pots today, and am very pleased with what I found. Photos will follow soon!

David Barber said...

I like the brown patch on the first pot you posted. One thing that I've struggled to get to grips with in pottery production is the happy accidents that occur, despite all the best planning. You just have to roll with them. Great blog, I really enjoy your writing.

Peter said...

Hi David,
Good to hear from you, thank you for your thoughtful comment. I often get conflicted about the happy accident side of potting, and would like to roll with them more than I do! I was looking recently at a youtube video of Don Reitz making a bowl, and it was lovely seeing how he deliberately made it "wobbly" and pulled, marked and stretched clay, making an everyday form new and fresh. There is so much to learn.., and then there is learning to let go!

Linda Starr said...

Your pots on the beach are wonderful to see, hope all is well

Armelle Léon said...

Beautiful golden crystals, it seems that spring is good for you, nice !!!

Peter said...

Hi Linda and Armelle,
Lovely to hear from you both. Things are OK here, but I am getting rather tired towards the end of most days so haven't quite managed to update the blog! I have been making lots of mugs on the potter's wheel and some bowls too. It is nice to be more productive in the studio.
Kind thoughts, P

Amy said...

thank you for your thoughtful post, saying you hadn't seen me blog in awhile. I just saw it. Yes, I have taken a break. It's been a tough fall and summer in some ways although I'm seeing things change for the better. It's so good to see you're back at it. Your kindness made my day...

Peter said...

Good to hear from you Amy, glad that the comment helped lift your spirits. Kind thoughts, P