A very long interval

Not that anyone is reading this ... but sorry. About four months ago my computer packed it in, and it took quite a long time to get a new one (I wanted a small low energy consuming machine) - a long story in and of itself. Then we got broken into and they stole my camera. Sigh.

In the interval though there is MUCH to report. Chiefly, I almost melted my kiln. I had a few large flowerpots coated with a black slip that I was firing to vitrification, ^6. I did it during one of our market days. When I got home at four the kiln was at 600 C. I cranked it. Unfortunately, I kind of forgot about it. I checked it a couple of times, the elements were getting old so I didn't keep on top of it like I should have. When I turned it off six hours later it was at 1175 C ( about ^5). That was close enough, I didn't need glaze maturity, and I wanted to go to bed. When I unloaded it though, all the bricks had changed colour, and had cracks down the middle. It looked pretty bad. The one shelf I had in there had sagged on to the floor of the kiln, and all of the stilts had turned a medium brown. My local expert tells me these cordite shelves must reach ^ 13 to warp this bad. Not good. Clearly, the pyrometer had packed it in for that firing and not giving me an accurate reading. Then again, I had drank a couple* beers so ... I'm not sure if it read 1375 C. Doesn't really matter now.

The cracked bricks are interesting to me. They must have expanded and then vitrified enough to stick together, then as they cooled, they cracked down the middle as they shrunk. My kiln is now well worn and ugly. It's a bit of a shame as it's kind of my baby. But it is my fault. At least it prompted me to order new elements. I upgraded from 37 amps to 40 amps for the kiln. The new elements are a thicker gauge so they should last a little longer.

Yesterday was the first glaze firing with the new elements. I had a set of 8 salad bowls and a large mixing bowl commission in there and they turned out quite nice (waterfall over oatmeal). Unfortunately no picture. But here's a picture of me at the first stage of making a large berry bowl. Tomorrow I'll trim it.

Super slow cool

I fired a glaze load on Sunday. It was full of two combinations, Waterfall Brown over Oatmeal, and Waterfall Brown over Bright Sky Blue. Normally I follow the revised Roy & Hesselberth schedule, but on Sunday I just about feel asleep at 7:30 pm after working in the sun all day while watching a documentary on bill fish, and went to bed while the kiln was at 45% power. When I woke up ten hours later I finally remembered.

Ooooops. The kiln cooled from 1050 C to 800 C from about 6pm to 8 pm when I finally turned it off

The R&H matte glazes are such that they require slow cooling to turn matte. It's a generalization to say it's because of stability issues, but it is largely true. Unfortunately, it turns out that extreme slow cooling makes Oatmeal look quite boring. It's a completely uniform and dull oakish colour.

The glossy glazes on the other hand require slow cooling to reduce their glossiness a little. The slow cooling allows some crystals to grow which adds interest. If you extend that slow cooling it seems you might get a matte glaze. I'm very happy to report that this extremely slow cooling makes Bright Sky Blue a much more interesting glaze. It turns completely matte with creamy speckles in it; moreover it has a very interesting texture.

The pots in this firing are so beautiful that I'm going to use this schedule for this glaze from now on. Of course, this means that I have to glaze a full load with all the same glaze, but it will be worth it.

Damp Box

It used to be the case that I worked from home. I would be "at work" at 6am so that I could be done by 3. This gave lots of time for pottery or anything else. And of course, I would be able to take an hour to trim if some pots were at just the right stage.

I no longer work from home. It was a difficult decision to switch positions because of the freedom of working from home. I was worried I wouldn't have enough time to keep enough production. I was worrying about the wrong thing. I can easily throw a kiln load in one sitting on a weeknight. The problem is scheduling trimming and handle attachment and other tasks that need to be accomplished during drying. This problem is especially compounded in the summer (peak production), or when the kiln is on since things dry faster.

Enter my latest project. Without this damp box I am completely relegated to making lidded and handled items to the weekend. Periods of time when I can repeatedly go to the studio and check drying progress. In order to make more pieces which require attachments I needed a more controllable drying situation.

I simply used some scrap lumber that I appropriated from the neighbours fence when it was replaced and built a box between two shelves. The interior is 30 inches by 27 inches by 11 inches. Obviously it's not huge. In fact it won't accommodate medium to large platters. But that's the purpose, it's for mugs and pitchers. The plastic I had lying around from renovating our bathroom and the hinges came off a dog fence that I built for my previous office (one dog had a habit of puking in our area). They're damn hinges, spring loaded to keep the door closed, very nice. So all in all I didn't spend a cent and I had something fun to do while the kiln fired. (Leo's cups are in there cooling as I type.)

The picture shows its inaugural run. Since the kiln fired to 1200C yesterday, it gets pretty warm in the garage. Too warm to allow these mugs to cool slow enough so the handles don't pop off so instead of just draping them in plastic like I normally do they got put in to the new toy. It worked great.

Sues bigger lamps

A really long time ago. My then sister in-law asked me to make her another set of lamps. Here is the first set she asked for. I think it was a year and a half ago or maybe only last June, she saw us at the Farmers Market again, and said that another set would be great for the living room. Larger though. Like two feet large. I explained that the tallest I can make is governed by the available space in my kiln and twenty one inches is the most I can make. These are about nineteen. I hope it's enough.

I think I mentioned in a previous post that I had to make these. I threw them about two months ago and quite honestly it's the first time that I've ever thrown a set using sectional construction. They turned out reasonably close to each other. About half an inch different in height and the profile is quite different between the two but the glaze does make them an obvious set. I hope she likes them.

For the M^6G fetishists out there, this is Waterfall brown over Bright Sky Blue. It's cooled to 1050 C (from ^6) as fast as the kiln will cool (about 45 minutes) and then cooled at 70 C per hour until 800 C. This is more or less the schedule that R & H now use as published on their site. If you hold this combination at 1050 C for an hour or so after the initial cool you get a very beautiful lustourous brownish matte. But I know Sue wanted shinier brown so I didn't do the hold.

Teacups for Leo

In real life (away from clay) I work at a video game studio. Part of my work there involves liaising between technical artists and my group of programmers. Every two weeks on Fridays we celebrate our pay day by electing one poor computer geek to prepare some kind of dessert for the group. Last Friday was my turn.

Now, I'm an alright cook - I do the majority of the cooking for my wife and I, but when it comes to sweets she rules this roost. So, the extent of my contribution to the Friday payday morning dessert was supplying the vessels for my wifes excellent coffee mousse. (It's awesome and easy.) The reason I bring this up is that the technical director for the central art team was quite taken with the ash glazed teacups that I produced for my test cases during the winter. He liked the glossy black with green ash on top so he asked me for a set.

So, I finally got off my butt, cleaned up the studio and threw a board of yunomi for Leo. Here they are, I'll probably throw another board later as these didn't come out at all similar. He asked for six and while he said he doesn't care if they're identical these are mostly unacceptly unique to each other.

Waterproofness

Sorry ... no work lately. I spent the last weekend cleaning up and organizing the studio, and this weekend waterproofing the area around my wheel. I used a patio deck coating and it turned out pretty damn good. I laid it on extra thick for durability. Now I'll be able to spray recklessly in order to clean up.

Soon I will begin work on a couple of very large lamps that I've been commisioned for. I've delayed too long on those, have to get to making them.

Also, I had lunch with my first and only ceramics instructor and he reminded me of a cone 6 base glaze formulation by a local, so I intend to try that out soon as well.

Spearmint and Licorice Tests

Here are the results from the last firing. I learned that a lot of the beauty from the previous round did come from the extra thick oatmeal. So, in the future, I think I will double dip the base glaze before applying the ash glaze. Each image is the base glaze with blue frasca, oatmeal frasca, field mouse brown frasca and spearmint frasca from left to right.

oatmeal



field mouse brown



licorice

The licorice tests are interesting to me. The ash glaze seems to have had the affect of fluxing the licorice in such a way that only very little glaze was left at the top of the pot. I've not yet decided if I actually like it.

I think I really like the spearmint quite a bit. I'm tempted to try another blue, perhaps using colourants from bright sky blue. Or, perhaps just adding some rutile to the regular frasca blue.

I'm not sure yet what I will try from here. Perhaps a different ash glaze recipe?

Spearmint Frasca

Today I mixed up a "Spearmint Frasca". That would be the base Frasca glaze with the Spearmint colourants as per Roy & Hesselberth. 4% Copper Carbonate and 6% Rutile. I added a bit too much copper carbonate though, an error reading the calculator. Not that big a deal I don't think.

I'm going to fire 12 test pots tomorrow, three flights of four pots. Each flight is either glazed with Oatmeal, Field Mouse Brown or Licorice, and each flight of four has an overdip of ash glaze. The ash glazes are Blue Frasca, Oatmeal Frasca, Field Mouse Brown Frasca, and Spearmint Frasca. I'm redoing the oatmeal tests because I thinned it out a bit. It was VERY thick in the first series of tests.

I'll post in two or three days how they turned out.

Oatmeal & Field Mouse Brown Ash Glaze

I did my second cone 6 ash glaze test fire yesterday. I tried the Frasca base glaze with colourant additions as per the Oatmeal and Field Mouse Brown glazes in Roy & Hesselberth. I think they turned out very well. In fact if I was English I would say I'm well chuffed. Not sure exactly what that means though.


From left to right:

• Oatmeal Frasca over Bone
• Field Mouse Brown Frasca over Bone
• Blue Frasca over Oatmeal
• Field Mouse Brown Frasca over Oatmeal
• Oatmeal Frasca over Oatmeal

I'm very happy with the Blue Frasca over Oatmeal. I think this combination is a winner.

It may seem a bit strange to try Oatmeal and Field Mouse Brown. They're quite similar in the colourants. In fact, they're identical save for a very small addition of cobalt carbonate in Field Mouse Brown. The results in these additions to the Frasca Ash Glaze are noticeable but, close enough that I would probably just save the cobalt carbonate and go with Oatmeal. The reason I did both though is because I think both of these glazes are amazing.

There is a caveat though, the Oatmeal under the ash glazes was applied quite thick. I'm going to redo these tests with more appropriate glazing.

Next up, I'm interested to see how these look over a black glaze. I'm also going to try the Spearmint colourants in a new batch and try that out. I suspect it will look fantastic.

Cone 6 ash glaze tests

I've been meaning to start a blog where I can record my work for a long time. So ... here it is. I work at cone 6 in oxidation. You can see the web page that I keep with my wife at www.m2crafts.ca. She is a soap maker and I am a potter. On this blog I plan to record more of the behind the scenes goings on in my studio.

I've recently been doing some tests to develop a cone 6 ash glaze so I though that this would be a good time to start the blog. The base glaze "Frasca Ash" that I have started with is due to Harry Spring. The PMI article is available online.. I had tried this glaze before with moderate success among a larger group of tests, so this time around I will concentrate on it alone. Here's the recipe in case that link goes down:

   56% Unwashed ash
   11% Calcium carbonate
   11% Custer feldspar
   11% Silica
   11% Ball clay

Harry adds 2% cobalt carbonate or 4% copper carbonate for blue and green respectively.

The ash I'm using is sourced from my charcoal grill. Mostly. I have gotten some from my parents fireplace too. To prepare the ash I seive twice, once through a very coarse strainer and a second time through an 80 mesh chinois. The chinois makes it much easier to get the ash through as you can be much more vigourous about it without worrying about spilling.

For the first test I did three batches. I tried this recipe with plus or minus 5% ash. I used the blue variant for colour. The one on the left is with -5% and the one on the right is +5%. I much prefer the middle one, which is the recipe as it is. The ash glaze is dipped over Bone by Roy & Hesselberth. But this is Bone that has been in a bucket for my production year, so it's changed slightly due to solubles and contamination it doesn't normally look that yellow.

I don't really like the look of the glaze quite frankly. I think it's too bluntly blue. Some of the rivulets are nice, but lack that really authentic ashiness. Regarding the former criticism I'm going to try the baze glaze with some colourants as for other glazes that I like. And the latter problem ... I have no idea how to make it more authentically ashy. I will probably test with a different base glaze to try to solve that.