Tuesday, 10 May 2016

A new website and a good May firing

Well, I can barely believe it's May already, how quickly this year is flying by! After an extremely cold April in the UK, things have warmed up alot over the last few days with a beautiful, sunny weekend and now the air is even feeling quite hot and muggy.That usually means rain will soon follow, if not storms!

Here's a quick plug for my new website "Mark Smalley Ceramics".. the link for which you may have already spotted in the right hand column of the blog. At the moment I'm running it alongside the shop on Folksy, so there are different pots listed on each. Below is a screenshot of the entry page, and clicking here will open the site in an new window:


I hope you might like to visit some time. It's still a work in progress to some extent, so if there are any problems navigating or purchasing work, I'd really appreciate your feedback via a comment or e-mail, thank you.

Anyway, new pots have been made and the first electric firing of the month was pretty successful, especially as I finally achieved a grey finish which I like very much. It's actually my hybrid dolomite glaze over the black iron engobe I developed recently, and I'm delighted with the variegated, optical hues this produces. The smooth, satin surface texture is very pleasant to touch as well. The five pieces below were dipped in the engobe and bisc fired again before applying the glaze:

Espresso cup

Large coffee mug

Jug

Vessel

Footed cup or bowl

In future, the engobe should work if applied to leather hard ware, perhaps even bone dry, I will have to experiment further..

The next two pieces, had the engobe sponged on which gives a fairly random, uneven application. I felt this worked rather nicely on the tall, lidded jar, but maybe less so on the tea bowl where more of the clay body shows through. A matter of personal taste perhaps..

Lidded jar

Large tea bowl

And finally, a piece I think is quite special .. a globular vase with black "Nezumi" slip and dolomite glaze. This piece received exactly the right glaze thickness and an ideal amount of heat work which has allowed some of the slip oxides to rise through to the surface of the glaze. Just occasionally the kiln gods grant you exactly the result you had envisioned before the firing!

Vase,  width approx 4 inches

Vase; glaze closeup

Thank you for reading!

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Never give up, the best is yet to come

Wednesday, 13 April 2016

There are no shortcuts in ceramics

No one said making pottery would be easy, and from my experience, very few steps in the process are simple or straightforward. Well, that is partly what makes it so rewarding when  pleasing results finally emerge from the kiln .. a bit like getting to the pinnacle of a mountain one has tried to scale several times (not my cup of tea I hasten to add, as I can't stand heights!).

I say that because events last week tested my mettle somewhat. The electric kiln is getting on a bit now at twenty years old and having spent hours replacing all the elements a few weeks ago, it then failed on me twice within six days, both times very close to the end of a glaze firing!! The word "disappointed" doesn't quite cover it, but there was no option other than to plough on, repair the kiln, then re-pack and fire it a third time. So I was extremely relieved last Saturday that it made it to cones 9 and 10, even though it did go a little too high again. I find that with new elements, my kiln fires very quickly and even with a short soak, it's easy for the temperature to overshoot by a cone.

The pots on the top shelf tend to get a fair bit more heat work and some of the glazes were more translucent than normal. I was still happy with most of the pieces, especially this cup where the under-glaze decoration has bled slightly into the dolomite glaze:


And here are some of the other pieces from the firing:






 









Thanks for your visit!

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Never give up, the best is yet to come
















Monday, 28 March 2016

So where did this glaze go wrong?


Ahem .. well.. adding an extra layer of the matt gold glaze (a simple recipe containing kaolin, manganese dioxide and copper oxide) and refiring them a cone higher didn't work terribly well! The firing yesterday went to cone 8 (and 9 as well accidentally) .. yet the gold colour of the manganese has still failed to emerge,  or rather it has appeared but only sporadically. Most of the glaze has come out dull and way too dark (as per the first attempt) and I'm rather baffled as to what has gone wrong.

I tested the same glaze on small head sculptures some years ago and they came out pretty well .. admittedly the finish wasn't perfectly even:

Ceramic sketches, 2008

And decided to try this again now as I figured this glaze would work well on some of the more textured pieces I've been making lately. So the finish above was what I was aiming for, but this was a new batch of glaze, a new supply of manganese and copper oxide and these were some of the results which were very different, and on the whole, didn't live up to expectations:

Tea caddy, carved from a solid block of clay
Bottle vase, height 3.5 ins


Vases

Another larger vase (not shown) barely had any gold hue at all, and two layers were brushed on, so I would be surprised if glaze thickness is the issue here. Having said that I did use a small amount of CMC suspender to avoid brushmarks and perhaps this reduced the glaze thickness? It is puzzling and perhaps the new batches of materials have something to do with it. Also my electric kiln elements are new so the firing is faster than normal .. could it be insufficent heat work in parts of the kiln? Certainly the cones dropped very quickly at the end, and strangely, cone nine, which was placed directly behind cone eight, bent exactly in tandem, something I've never seen happen before. I assume this was because it's slightly further away from the spy hole, but would a centimeter or two make so much difference?   

Although the colours are muted, I feel the matt metallic finish is very effective on this heavily textured vase:

Oval vase, height approx. 5 ins

I guess dipping could improve application, but I don't fancy the health hazards of making a bucket of glaze which contains 30% metal oxides! The cost for a start would be fairly prohibitive.

Well, if anyone has worked with this kind of glaze and would like to share ideas, please do leave a comment.

On the bright side, this dotty bowl was glazed with a new batch of my translucent dolomite recipe, and I was very happy with the result:

Bowl, height approx 3.5 inches

And this little hanging vase with nezumi style shino came out okay too .. a piece I've been meaning to fire for ages:


Anyway, it's Bank Holiday here today so the weather is grim, grim, grim .. high winds and lashings of rain! Which partly explains why I'm indoors tapping away on the PC. Have a great week everyone, and thanks for reading!

Update: I now think there's a good chance that the dullness and lack of gold finish is due to the china clay content being too high, combined with the clay body of the pots being very refractory. This could explain why the glaze hasn't melted sufficiently ... so, the next step is too make another batch with a higher proportion of metal oxide, and fire it a third time. However,  next time I will try it out on just a couple of pieces! Like many potters I suspect, I am sometimes guilty of ignoring the old saying "Test, test and test again!"



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                                             Never give up, the best is yet to come










 









Sunday, 27 March 2016

The quest for a matt grey glaze continues..


So, it's been a while and I'm still trying to develop that elusive, matt "grey" glaze! So far I've concluded that black iron oxide only produces grey either in an engobe which isn't fully vitrified, or in larger percentages which gives a very dark grey-brown, verging on black. Ideally, I'm looking for a light grey like this, but with more sheen to it:


Test tiles, fired in oxidation to cone 9

The two test fires on the left were pleasing .. made with an engobe (clay, potash feldspar and a little raw ash), plus small amounts of black iron oxide, nickel oxide and cobalt oxide. But since I started using a new batch of black iron I've been unable to repeat it, instead just obtaining various shades of green-grey or brown. Incidentally, the test piece on the left was made by mixing red earthenware with a coarse raku body .. I've found that this combination can withstand cone 8/9 firings in an electric kiln).

The following tiles were made with a matt ash glaze (adapted from John Jelf's ochre ash glaze recipe) and varying amounts of black iron, cobalt and manganese dioxide (instead of the nickel):

Test tiles fired in oxidation to cone 9
The test second from left (above) was close but no cigar .. and funnily enough this was made with a cheap black iron bought from Ebay which looked more impure and browner in its raw state than those bought from pottery suppliers. The other sources of black iron produced much browner hues:



The tile on the left looks grey but is really an extremely dark brown (over 4% black iron oxide).

The most convincing grey I've concocted so far is with another engobe recipe, here applied thinly by dipping a bisqued pot, then fired to cone 7:


Still too dark to be used on its own, and possibly verging on black rather than grey. The engobe recipe if anyone would like to try it:

HVAR ball clay    50
China clay          50
Potash feldspar   20

plus, as a percentage of the total dry weight: 8% black iron oxide, 3% manganese dioxide, 1% cobalt oxide
                                         
Since then, I've come across a couple more recipes which use a combination of rutile, cobalt and nickel to make grey, so this provides yet another avenue of research. Ofcourse one of the problems being that rutile can vary alot in terms of its chemical make up .. 

Anyway,  I've still found time to produce a few pots here and there. Below are some pieces fired fairly recently in  the electric kiln. The dolomite glaze on the first three pieces is a mixture of my usual dolomite glaze with a transparent ash glaze. The result is less opaque and allows more of the iron oxide brushwork to show through:




 Plus two pots with the old dolomite glaze:



And finally, a couple from the latest firing, both with metallic glazes:

Lidded container. Metallic over matt ash glaze

Sculpture, height approx 8 ins

Most of the pieces in this firing were coated with a matt gold glaze (active ingredients: manganese dioxide and copper oxide) applied by brush and came out rather under fired. I was probably over-cautious in firing them to cone 6/7 only, as I didn't want the manganese to flux and become too shiny. Also, the gold colour was rather patchy, so I brushed on another layer and am re-firing them today, to cone 8. It will be interesting to see what effect the extra temperature has on the glaze, and hopefully I may have a few good pieces to show next week!

Happy Easter! And thanks for reading.

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Never give up, the best is yet to come!


Sunday, 8 November 2015

Some recent results from the electric kiln

I've been meaning to update my blog for some time, and now that Tim Lake (thanks so much, Tim!) has very kindly mentioned it in a recent article in Ceramic Review, I figured it was high time to upload a new post.

Weather wise it wasn't the greatest of summers .. a constant procession of windy days has stopped me firing the gas kiln outdoors more than a couple of times, so I returned to using my electric kiln for bisc and glost firings for a while. Incidentally, I don't view electric firing as in any way inferior as a method of producing pots .. the results are different, but can often be stunning in their own way. However, I do think it is more difficult to create visually arresting glaze surfaces in oxidation, and I enjoy the challenge of trying to produce something new and exciting using this method.

Lately, I've been playing around with applying thick textures to my pieces and am now working on developing new glaze and slip recipes which will work well with more random and irregular surfaces. One of the things I want to create is a greyish glaze, probably fairly matte with some variegation in hue. I managed to create a grey slip easily enough, using black iron, manganese and cobalt (also one with nickel oxide instead of the manganese) but the same combination in a more fluid glaze has proved unpredictable to say the least. This is the closest I've come so far, but the black iron and/or manganese in the glaze gave it a rather brown tint:



Interestingly when applied thinner, the cobalt begins to dominate and more of a blue-grey appears with specs of brown. As is so often the case, I rather like the result but it's still not really what I'm aiming for. On another test piece I used equal proportions of cobalt oxide, nickel oxide and black iron oxide and less wood ash than the recipe above to make the finish more matte. The surface texture of the glaze turned out perfect but the colour reminded me of greeny brown cowpats, not quite what I had in mind! Funnily enough, where it overlapped with a white shino glaze on the inside it was actually a wonderful charcoal grey in places! Such is the chemistry of glazing .. complex and sometimes impossible to fathom. I plan to try reducing it in a saggar and see if this changes the colour to something easier on the eye. If anything interesting occurs, I'll post a pre- and post- reduction photo in my next post.

Update 12th Nov: actually I managed to take a shot of the piece today, so here is the before photo:



I am very taken with the texture and feel of this glaze .. and I suspect that the colour would be darker if applied more thickly. You can see the small area of greyer glaze around the inner rim at the back of the cup. 

Anyway, the search goes on ...

Oh, and one other thing which really amazed me recently. The celadon coffee cup below had been fired in the gas kiln to earthenware temperatures with a little reduction .. and the glaze came out completely unvitrified but one could see that it had already taken on a distinctly grey colour. The piece was later refired to cone 9 (around 1260 degrees C) in the electric kiln and of course, I expected the glaze to oxidise and come out a shade of amber yellow. Incredibly, it stayed this beautiful pale grey with some iron bursts, so even at a temperature well below 1200 degrees C, the glaze surface must have been sufficiently sealed to prevent the iron oxide molecules from re-oxidising. That may not be surprising to some people, but I for one didn't know it was possible.



Here is a selection of pieces from my recent firings, a few of them are now available in my folksy store:

Round bottomed cup with dolomite glaze
Vessel with maroon slip glaze
Cup or bowl, approx 3 ins height
Bowl with dolomite glaze, width approx 4 ins

Carved bowl, approx. 3 ins height (sold)
Sake cup with Oribe glaze
Cup or bowl with slip and Oribe glaze
Vase with Oribe and dolomite glazes, height 5 ins
Saggar-fired vase with crackle shino glaze (sold)
Textured bottle vase with dolomite glaze
Coffee cup with blue-grey glaze
Coffee mug with Nuka glaze (sold)
Bowl with dolomite glaze, approx 4 ins wide

Thank you for looking!