Building a kiln

Ive wanted to get back to basics and build a wood burning kiln for a while now and with the street starting to warm up, I thought this weekend would be a good opportunity to make a start.

Using a combo of traditional bricks to create a base and the sides, I used white fireclay bricks on the inside to give it an extra layer of insulation.

I've chosen to make a 'downdraft' kiln, which means that instead of the heat going out of the top through a chimney, the fire comes in at the bottom circles round the inside and can only escape through a hole at the bottom that connects to the chimney. This is helps get the kiln even hotter.

Overall pretty pleased with the end result. It's a bit dodgy looking, but not bad for a first attempt. Will camp out next weekend and fire some pots in it...! 

Reused an old kiln lid for the top

Reused an old kiln lid for the top

Creating the base

Creating the base

A mixture of dug field clay and hay. The hay makes the clay stronger and stickier. 

A mixture of dug field clay and hay. The hay makes the clay stronger and stickier. 

After lighting it, we checked for smoke leaking and plugged the holes with more clay/hay

After lighting it, we checked for smoke leaking and plugged the holes with more clay/hay

Fitted the wood burning chamber with a shelf to allow the embers to drop down and get air into the flame. 

Fitted the wood burning chamber with a shelf to allow the embers to drop down and get air into the flame. 

Home made kiln and pit firing.

So the homemade wood burning kiln didn't work when I tried it.. it didn't get hot enough to transform the clay into ceramic completely and I ended up with a black bowl that half dissolved when put in water.

Its a shame, but I know what the problem was.. I didn't channel the heat into the kiln properly, so the heat from the fire was drawn into  the kiln and then promptly exited via the chimney. I should have made an airtight obstacle course for the flames before letting it up and out - which I will be doing, so watch this space.. 

 In the mean time, I had a go at pit firing. This is the most ancient  way of firing clay that goes back to nearly the dawn of humanity - digging a hole in the ground, putting your wares at the bottom and then building a fire on top.   

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I sprinkled copper and iron oxide on them to hopefully give them a bit of colour and then wrapped in foil to keep it on the pot. 

I tried to keep everything as simple and authentic as possible and don't glaze the pots like I do normally. I used a technique called 'burnishing' which is when you smooth out the surface of a pot to make it shiny before it's fired. This helps to 'close the body of the clay' meaning that there is less surface area and it goes from feeling like a flower pot to something much smoother. 

This closed body can, after firing, be waxed or oiled to make it more water proof, which is how it would have been back in the day before glazes were invented / discovered.  

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A well stacked fire 🔥 🔥 🔥 

After leaving the fire for a few hours to burn down, we put an old kiln lid over the top and sealed it with mud around the edges. This is to keep the heat in and starve the fire of oxygen, which should result in a reduction atmosphere which can intensify colours. 

Unfortunately my plate didn't survive the firing. It wasn't that thick so I can only guess the uneven heating or cooling was too much for it and it cracked.

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Here is my pot, after being rubbed down with a scourer and then waxed and oiled. The black patches are where the carbon from the fire stained the body and the white area is where it was too hot and the carbon would have burnt out.

There are a few other colours on the piece, golden yellow  and red which were from the oxides I applied. Iron ore and copper ore would have been used in ancient times for their pigments, well before they were discovered to be metals.  So it's not cheating to add it.

Too cold to pot!

I used to really enjoy the cold weather.. but now I can't wait for it to start to warm up again.. one of the main reasons why is that my pottery workshop is FREEZING. Literally.

Cold clay is a misery to work but at sub 0'C tenperatures, the water in the clay starts to freeze and creates weird cracks in the block of clay that have to be kneaded out later. 

To keep myself busy, I've been learning about the much warmer craft of forging. I had a few of the necessary bits already, so I only had to buy a blow torch to have a crack at making simple rings. 

steel template ring in the sand mould.

steel template ring in the sand mould.

The first step is to fill half of the mould with Delft clay, which is basically oil and clay mixed together. The ring that I wanted to copy is then half pressed into the sand.

both halves of the mould

both halves of the mould

The top part of the mould is then placed ontop and filled with sand which is then compacted down.

Pulling the two halves apart reveals the mould. 

Channels are then cut into the mould to let the liquid metal in and let air escape. 

As this was my first attempt, rather than melting down silver (melts at 950'C), I found some scrap aluminium that melts at a lower 600'C.

Here is the result: 

ring with sprue still attached

ring with sprue still attached

The sprue is then cut off and the ring tidied up. I used a dremel to do it, but I do have a lathe from my grandfather's toolkit that I'm trying to figure out, as it would be perfect for tidying up rings.

I'm fairly pleased with the first rough attempt and will definitely be trying it with silver and maybe some interesting alloys like copper and silver (which is a Japanese metal called shibuichi), gold and silver (ancient alloy called electrum) or even a mythical / legendary metal called 'orichalcum'.

Long time no blog..

As well as my workshop being freezing cold (which I can warm with an electric heater) the clay also gets very cold and is much harder to warm up and is almost painful to throw with, meaning that I've been doing pottery less, which sucks!

However, before I started slowing my pottery down, I did manage to get a decent result from the local reduction copper glaze I posted about previously and here is a piece I was commissioned to make for a colleague:

I've also been practising mugs, consistency and handles, which can be seen here:

In the finished piece, you can see where I have layered the local reduction glaze thicker, it has created red / blue / purple streaks and run slightly. I think that this glaze is particularly influenced by the firing schedule and so it might be worth making some test tiles and seeing what effects I can produce by adjusting the firing.

This is why I love pottery..

I've been thinking for a while about making a glaze known as 'copper red'. This might just sound like words, but copper glazes only turn red in a reduction atmosphere - where there is no oxygen available, such as in a gas kiln where the flames burn it all off.

I only have an electric kiln and I'm scared of using gas, so I turned to a really interesting and not that widely exploited material known as silicon carbide, which is the grit on most sand paper.

By mixing just 0.8℅ of silicon carbide into a copper glaze, it can create a reduction atmosphere within the glaze itself. At high temperatures, the silicon carbide changes into silica (glass, which is obvs very handy to have in a glaze) and carbon. Carbon is very reactive and readily grabs and steals any oxygen available in the glaze and changes to carbon monoxide and dioxide.

This gas then bubbles out of the glaze taking the oxygen away from the copper oxide, transforming it into copper metal (it also does this to other metals too) which is pinkish / red.

The reason this glaze is tricky is because as the gas exits the glaze, it causes it to bubbled and if the glaze cools with those bubbles in, you'll be left with an ugly and unsafe bit of pottery. You can counteract this by slowing the heating of the kiln down towards its top temperature of 1200°C.

Here are my results: 

... but those are green / blue, not red!

Yes, they are. I followed the recipe to the letter and got an idea of how the speed and temperature of the kiln should work from the recipe, but the glazes have come out copper green, indicating pieces were fired in an oxygen rich environment.  

As annoying as this is, I'm actually really pleased with the glaze and I might even say this is one of my favourites so far..! For those who want to try, the glaze is called Panana Red fired in oxidization and you don't need to add the silicon carbide if you want the green colour.

It would be a case of back to the drawing board, but I got in contact with John Britt, author of Mid-Fire Glazes and asked him if he could offer insight (I was following his instructions after all) and here's his reply:

Totes chuffed that he took the time to reply to my question, he's like the boss of glazing and has tons of really useful YouTube videos.

So I'm going to follow John's advice and we'll see how the next batch goes! 

NB - the glaze shouldn't be used in functional pieces as it can leach out into food. It can be used on the outside however. The bowls shown are just test pieces and will be chucked away. As someone on Facebook once said "You might know it's not food safe, but pottery lasts a long longer than you will, who knows where it will end up?".

Processing, firing and testing Norfolk clay..

After drying all the clay I collected, I then separated out orangey / yellow chunks, as these will be high in iron and affect the colour of the clay. I'll make a separate batch of iron rich Norfolk clay later. 

I then added the dry clay into a bucket of water and let it slake down into a slurry, which I mixed with a blender to get smooth. I ran the mixture through a sieve but amazingly the clay was really pure and contained no stones or sand! This means it can be pulled out of the ground and thrown on a potters wheel as is.

The clay slurry was then poured into plaster moulds and left to dry to useable hardness. (Plaster helps to draw out moisture).

Testing

Once the clay had dried enough, I made several test bars, measuring 5 inches (my old school ruler didn't have cms). 

I let the test bars dry completely before measuring them again - this is to get an idea of how much the clay shrinks when air dried.

I then fired two of the bars to 1050°C and the other bars to 1200°C. The tests below are on the lower fired bar.

Shrinkage

After their firing, I measured ther lengths again and calculated how much they had shrink ((original length - final length) / original length) * 100 which was about 8%.

Absorption

To calculate the amount of water the fired clay body absorbs, you first weigh the bars post firing and then submerge in water for 24 hours. The formulae is ((dry weight - wet weight)/dry weight)*100 and worked out as about 22%.

Hardness

This is a simple test where you scratch the fired body with a nail to see whether it crumbles and if so, how much by. The nail didn't scratch the clay. 

Slumping

This is to see how the clay distorts when being fired and you simply place the test bar so it's not supported across the middle and after firing you check whether there is any bend in the bar. Happy to say there was no slumping.

The results of the tests indicate the clay is a typical earthenware surface clay with low (less then 15%) shrinkage and high absorption.

Fired to 1200°C

At the higher temperature the clay melted and stuck to the base I fired it on. Interestingpy the clay went from a cream colour into a mustard yellow, indicating the presence of iron, which makes sense, given all the orange bits I picked out. 

The clay has almost no absorption now and resembles a stone or glass. This is because all the chemically bonded water has now been removed at the higher temperature and the crystalline structure of the clay now won't allow any water in.

The high fired clay has shrunk massively when compared side by side.

The high fired clay has shrunk massively when compared side by side.

Harvesting clay in Norfolk

I've been in Norfolk this weekend visiting family and what better way to take advantage of the trip than to collect some clay! 

We went to a local beach at Trimmingham which has exposed cliff faces that collapse onto the beach. After a short walk, consisting of me running up to mounds of earth and rubbing it between my fingers to check the plasticity, we found some clay.

A small stream came down from the top of the cliff and formed a slurry pit half way up.. which I enjoyed...

muddy feet or midget hands?

muddy feet or midget hands?

After searching for a bit, we found some nice looking grey clay without too much orange colour (iron) and filled a bucket.

While I was up the cliff, I noticed lots of orange looking slime which is called 'bog iron'. It comes from either iron in the soil being eroded chemically or by bacteria using the iron and excreting red iron oxide as a waste product. I knew instantly it was the latter, because the bacteria leaves a telltale oily film on the water's surface. In the past I've seen this and always assumed it was a rusting oil can or something causing the orangey slime oil, but no, it's totally natural.

Bog iron

Bog iron

Interestingly bog iron was one of the first sources of iron used in medieval times, which would be refined into pure iron metal. According to my limited research, refined bog iron actually has an advantage over modern processed iron ore because it contains more silica and this gives the resultant iron more rust resistance.. for a potter this is useful to know because it has implications should I ever use this orange iron oxide rich slime in a glaze, as silica is the glass base of the glaze.

While at the beach I also grabbed a load of seaweed..

Another mini history lesson warning! - when the Romans invaded Britain, they brought with them a great deal of technical knowledge, which included making glass. To melt sand into glass you need unfeasibly high temperatures... Unless you have a flux, which reduces the melting point.

The Romans had natrum, which is a salt rich mineral from a distant part of their empire containing dry salt lakes (Africa I think). After the Roman empire collapsed, so did the infrastructure providing natrum, taking the glass making capability and knowledge with it. 

After the dark ages, experimentations with new ingredients lead to new discoveries and one of them was soda lime glass which used sodium as a flux to melt sand, much in the same way the Romans did a thousand years earlier with their natrum. One source of this flux was seaweed which as abundant as it is potent.

In pottery, the ash of burnt seaweed can be applied to a bisque fired clay pot and it alone can cause the outside to melt and turn into a glaze when fired.. which is what I hope to do once I've dried out the seaweed in my oven! (Fyi the smell is outrageous). 

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Wabi Sabi...

For those that haven't read my 'About me' section, I should say that I learnt pottery in Japan while studying at uni there.

The fact that I learnt in Japan has obviously influenced the way I make pottery, such as the pottery wheel in Asia spins clockwise, not anticlockwise like it does in the West. This means I have difficulty on standard European wheels as everything is backwards to how I know. My 'default' teapot is a Japanese one and my bowls are automatically noodle bowls, instead of being for cereal.

Another, more deeper and meaningful way my tuition has had on me is the sense that, as aesthetic as Ikea vases are, they lack a soul - they are TOO perfect and tell us nothing of the creator or ourselves. So I look down on the slightly as they lack any intrinsic value.

That being said, hand made things can be equally as perfect as pottery from ikea, but to me that 'perfection' makes them boring and lacking in something much more important than perfection - wabi sabi.

Wabi sabi is a Japanese concept which doesn't translate into English very well but it's about reflecting on the passage of time, the ego and the impermanence of our reality. Its intrinsically linked with Buddhism but it's not a religous idea, it's a way to deeply connect with something.

One example of how imperfection can be more beautiful than perfection is the idea of a white bowl. The bowl is perfect, well made and suits the purpose it was created for but one day, the bowl is dropped on the floor and breaks. Rather than throwing it away, the bowl is put back together using a gold coloured resin as the glue.

Image source : www.thisiscolossal.com

Image source : www.thisiscolossal.com

Most people will agree that this bowl is now more beautiful than before. But why? Is it just because we like gold? I don't think so. I think it unconsciously speaks to us and reminds us not to be afraid of failure. Failure is a part of life and things can go wrong but lessons can be learnt and actually sometimes things can, inadvertently, become better than we could ever hoped.

Looking for the silver lining or 'gold coloured resin' isn't easy, it's one of the hardest things to do but if you can look at shards of broken pottery and smile, thinking about all the possibilities this mistake just created, then you are one step closer to understanding wabi sabi.

Multiple firings and delivering a consistent message.

I've recently been working on a few commissioned pieces, mugs and teapots and I unfortunately took the risk of applying a glaze recipe on them without testing it out first.. I'm lazy and like quick results. Unfortunately my haste caused bubbles and pits to form in the glaze, which are unsightly and dangerous because they have sharp glass edges.

The pitting was likely caused by the clay being fired too hot or not long enough (or the zinc glaze being applied to thickly..), which caused gases to bubble out of the clay body and the molted glaze didn't have time to smooth itself back out. To correct it, I decided to fire straight up to the top temperature, which is about 1240'C and then bring it down by 100'C per hour until 1040'C at which point the kiln could turn off.

The result was surprising. Most of the bubbles had gone and healed over and the colour, texture and shine of the glaze had transformed into something I like much more than the intended glaze.

The glaze has lost a slight metallic sheen and gained an extremely glossy surface with no microcrystals in like before. The glaze also turned a vibrant green colour and ran in places (which is always the risk when refiring fired glazed pieces) and I'd describe now it as 'green caramel'.

Something I've been thinking a lot about recently is 'delivering a consistent message' in art. Its not a concept I had heard about until the Great Pottery Throw Down on BBC1 last year, where the judges used it as a way of gauging how good contestants'' work was.

In the past I used to think that 'art', particularly modern art, was just made up nonsense for people to make money and as there is no objective way of knowing whether something is good or bad, it makes it all meaningless.

But this idea of 'delivering a consistent message' means that while something may be subjectively good or bad, how successfully a piece delivers its message, whatever that message is, can be more objectively measured. That is to say, if something if a total mess and doesn't make any sense, what is the message its trying to convey? But if something is an intentional mess and there is a clear, identifiable theme running throughout several pieces, then its easier to see the message the artist is trying to deliver and that to me is what makes a piece / pieces good.

What does this mean? I suppose it means I need to think about my message and what it is I want to say about clay / chemicals / pottery / myself / the world.

Raku...!

I was recently meant to be attending a workshop on raku (traditional Japanese firing technique) but due to heavy traffic on the m25 caused by the French, I couldn't make it.

Sad times, but I made a few pieces for the workshop from raku clay (contains sand and ground up bisque ware) and thought I'd try it myself, as I had read you can do it in an electric kiln.

I filmed it all on my GroPro and edited it together (first for me..!)

 So the kiln has to reach about 900'C and the glaze on the pieces should be molten. There's a few ways to check that it's molten... None of which I did properly annoyingly.

Once the glaze has melted, you take the pieces out and put them in an oxygen depleted atmosphere with a flame (reduction)... So into a box of sawdust with a lid on. As the flame burns it uses all the oxygen in the box but needs more and so it starts to pull it out of the glaze, which should convert copper oxide into pure copper and create metallic effects.

Either because the glaze wasn't molten or because the box wasn't airtight, the pieces didn't get a metallic lustre.

Even though it didn't go as planned, I still really like this piece. A sphere is the strongest shape to fire as there are equal stresses throughout and makes it more shock resistant.

Even though it didn't go as planned, I still really like this piece. A sphere is the strongest shape to fire as there are equal stresses throughout and makes it more shock resistant.

This is my next favourite piece. The black parts are where the white clay body was exposed, without glaze, to the smoke in the box. The carbon has gotten into it and isn't going anywhere. You can see pinkish tinges to the copper green glaze where it has started to 'reduce' to copper.

This is my next favourite piece. The black parts are where the white clay body was exposed, without glaze, to the smoke in the box. The carbon has gotten into it and isn't going anywhere. You can see pinkish tinges to the copper green glaze where it has started to 'reduce' to copper.

Although the firing wasn't a success, I've learnt quite a bit about the process that will benefit me next time. I also know I shouldn't really fire indoors but I don't have outside space yet.. there's loads of bricks in the way and I was desperate to have a go.

I will be having another go soon and I've even tried to make my own raku clay from Shepperton clay, mixed with terracotta grog, SC grog and sand that I filtered out of the dug clay originally. 

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Transparent glazes and oxides

'd love to be able to make my own glazes, firstly because it keeps the cost down but secondly and most importantly I want to be as connected to my pieces as possible . This to me means knowing where my clay comes from (my parents' field!) And where the constituents of my glazes come from too.

Unfortunately it isn't practical to get all the ingredients I need from my direct environmen 😖 so I've come to accept that in the short term I'll have to make do with store bought ingredients. I can however understand and learn about all these ingredients, how they interact with the clay body, each other, the temperature and atmosphere of the kiln as well etc and start making my own.

I was fortunate (and jammy) enough to find someone selling a cornucopia of glaze chems for... £20. I went through all of my haul and calculated that I had over £900 worth of chemicals, including £200 worth of vanadium pentoxide which I hadn't even heard..

Using these ingredients and the instructions of John Britt in 'Mid-Fir Glazes' I've starting off by getting a good transparent glaze under my belt, which I can make in abundance. 

Now I am focusing on using oxides underneath the glaze to see what happens to them, which I think would give me an indication as to what would happen if I mixed a low percentage of the oxide into the transparent glaze directly.

Here are my results s far...

black iron oxide.. no idea why my hand is highlighter pink.. I only tweaked to colours a bit to make the photo look like real life..!

black iron oxide.. no idea why my hand is highlighter pink.. I only tweaked to colours a bit to make the photo look like real life..!

copper carbonate

copper carbonate

copper carbonate and iron oxide splodges 

copper carbonate and iron oxide splodges 

copper carbonate and iron oxide

copper carbonate and iron oxide

cobalt oxide (it's really blue in person)

cobalt oxide (it's really blue in person)

copper carbonate and red iron oxide premixed 

copper carbonate and red iron oxide premixed 

my favorite so far, copper carbonate 

my favorite so far, copper carbonate 

Floating blue

Loads of things to write about but thought I'd just do a quick post about an oil burner I recently made on commission (only made one before last year..!). 

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This mesmerising glaze is 'Floating blue' which gets its name from the way it looks like two glazes, a brown one under a blue one, which appears to float across the surface. The glaze can also be called hare's fur.

I love this glaze and the way it really picks out the iron oxide in the clay body and I think it is suited to ridges and ripples so it can gather and flow to create highlights.

#inlove

Glastonbury! (And raku!)

Ive been off for the last week and a half for Glastonbury festival, which is world famous as a gigantic music festival but there is so much more to it than just music.

While at Glastonbury, I visited the 'Craft fields' which is where ancient craft techniques such as willow fence making, copper jewelry making and whittling are demonstrated and you can have a go yourself. I'm obviously mostly interested in the pottery related craft and I saw one demo of locally dug Glastonbury clay being coiled into large vessels which was pretty cool considering my experiments with local clay. 

I was also lucky enough to have a go at Raku, a Japanese method of glazing and firing clay which creates amazing metallic lustres, crackes (known in pottery speak as crazing) and smoky effects. The glazes I used on my white bisque pot were identical to each other except one had about 3% copper oxide in it. 

I tried to glaze the pot in a way that would show both the body of the clay once fired, as well as the two glazes. 

I won't go into the details of raku as there is plenty of info out there about it, but here is the result:

You can see the copper oxide glaze on the rim has been 'reduced' meaning the oxygen in it has been ripped out, turning it into shiny copper metal.

You can see the copper oxide glaze on the rim has been 'reduced' meaning the oxygen in it has been ripped out, turning it into shiny copper metal.

You can also see the white glaze which has crazed in places as well as the nos black and smoky clay body.

You can also see the white glaze which has crazed in places as well as the nos black and smoky clay body.

I really love the unpredictable nature of raku and I'm actually attending a raku workshop in a few weeks to learn a bit more about it before I have  go on my own.

Back in business..!

After several desperate months of 'kerfufflery', I finally have a usable workshop again! It's about four times bigger than my previous space and a lot closer to where I live! Only downside is that I have to pay rent, boo!

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amazing 90's 'Glow in the dark' green and matt black paint to use as a blackboard!

amazing 90's 'Glow in the dark' green and matt black paint to use as a blackboard!

The landlord is super friendly and hoping to rent out a few of her units, so I'm looking forward to getting neighbours eventually..

I've started up some more experiments with Terra sigillata as I really want to have  ago at making Roman esk pots with modern twists, but I'm mainly just trying o get all my stuff in order and process ask the dried clay that's built up over the last few months.

Alcohol!

For various reasons I haven't been able to do any pottery recently :(

As before, I am having massive withdrawal symptoms for the lack of creativity and the knitting just isn't cutting it. Mainly because I keep getting aggravating my repetitive strain injury in my wrist when I do it...! Its so annoying and hurts sooo much.

I have therefore been looking at other things I can do to keep myself busy and so I have started making my own booze! Its actually ridiculously easy and I don't know why I haven't done it before.. well.. I do.. its because I'm lazy.

Anyway, the picture below is of some Pineapple cider and Blueberry cider I am currently making. I tried making cider last week and it was actually pretty good, especially the ginger beer I made. I've got a specific gravity measurer (hydrometer) which I can use to calculate the %age alcohol in each batch, which is pretty cool. The hydrometer can also be used with pottery to work out if a glaze as thick as it needs to be.

Terra Sigillata

During my research into what else I can do with local clay, I found out about an ancient method called Terra sigillata. This is the process of using suspended fine particles of clay, applying them to unfired greenware clay and then buffing it and polishing it until shiny. 

In Roman times this was a really popular way of 'waterproofing' fired pottery and it doesn't need to be fired twice.  

To make Terra sigillata I mixed a watery slurry of my local clay slip up and poured it into an empty plastic bottle (it was plastic even though it's a Bacardi bottle..). I then added half a tablet of Calgon which crucially contains something that weakens the electrical attraction between particles of clay and allows the individual particles to float freely. I've read that the water from washed ashes will do the same job.

I then drained off the suspended clay water, leaving the heavier slop at the bottom. It's very watery, but that's fine. I then brushed it on a greenware vase and built up a few layers before polishing it with a cloth. It's in the kiln firing at the moment, but I am excited to see what happens..!

The left is normal grey clay but the right one has had the Terra sig applied and then been polished.

The left is normal grey clay but the right one has had the Terra sig applied and then been polished.

This is both vases after firing. You can see the terra sig has turned a random orange colour and kept some of the shine. I am pleased with the result, but I would like to make a piece from scratch, knowing that I will terra sig it later. That way I can make it as shiny as possible.

This is both vases after firing. You can see the terra sig has turned a random orange colour and kept some of the shine. I am pleased with the result, but I would like to make a piece from scratch, knowing that I will terra sig it later. That way I can make it as shiny as possible.

Testing Results..!

This is my favourite and most positive result... The local clay at the bottom has melted! I should be able to use it to glaze my pieces and begin more testing with it..

This is my favourite and most positive result... The local clay at the bottom has melted! I should be able to use it to glaze my pieces and begin more testing with it..

My red beach rock didn't do anything and my roasted sea shells melted in places much like the chalk unsurprisingly (calcium carbonate)

My red beach rock didn't do anything and my roasted sea shells melted in places much like the chalk unsurprisingly (calcium carbonate)

The local chalk melted in places. The ash didn't melt but something in it, probably the sodium / potassium? volatized and turned the surrounding clay into glass. On the left, this was originally orange rust.. But it's turned metallic looking... After checking with a magnet, I can confirm its turned back into in pure iron!

The local chalk melted in places. The ash didn't melt but something in it, probably the sodium / potassium? volatized and turned the surrounding clay into glass. On the left, this was originally orange rust.. But it's turned metallic looking... After checking with a magnet, I can confirm its turned back into in pure iron!

This is a piece from a week later. I applied the local clay slip cover this lid and added a bit of rust (iron oxide) on the top.. for fun.

This is a piece from a week later. I applied the local clay slip cover this lid and added a bit of rust (iron oxide) on the top.. for fun.

This was salt.. I don't know what I expected to happen and I don't know what this means.. But it's interesting! I think salt works better in a reduction (gas) kiln.    

This was salt.. I don't know what I expected to happen and I don't know what this means.. But it's interesting! I think salt works better in a reduction (gas) kiln.

 

 

This is the result of the 1300'C firing. The slip has melted to form a greenish glass, which is thick in places and the iron oxide turned dark black with a metallic sheen. 

This is the result of the 1300'C firing. The slip has melted to form a greenish glass, which is thick in places and the iron oxide turned dark black with a metallic sheen. 

Testing materials

I am currently waiting anxiously for a test batch of my raw materials to finish firing at 1300'C.. I did put the kiln on last night but the wall socket stopped working part way through the cycle, causing a 'PF' message on the kiln controller. (PF indicating a power failure). So I put it back on today and monitored it until it reached 300'C... So hopefully it'll be OK tonight. 

Left to right (salt crystals, iron ore, local clay, local chalk, wood ash, Beach iron ore, roasted seashells and rust)

Left to right (salt crystals, iron ore, local clay, local chalk, wood ash, Beach iron ore, roasted seashells and rust)

Knitting

Unfortunately and frustratingly the electrics to my pottery shed aren't working :( so I can't do anything at the moment..

I've bagged up all my greenware to stop it from drying, so I can trim it easily.. But I'm pissed off.

I spend all week looking forward to doing pottery and it's a little soul destroying when you can't do it for reasons outside of your control.

I therefore needed some sort of creative fix to keep my mind busy and to feel that sense of achievement that I get from pottery... So I've started to learn to knit. It's something I've always said I wanted to learn, so what better time than now? I've bought a big ball of yarn and some knitting needles and started to make a really thin scarf.. 

It does make sense to learn something like this though, because you can whip it out wherever you are and crack on.. It's minimum effort and actually pretty fun and easy to learn on YouTube.

Current progress..

Current progress..

Leith Hill

In my attempts to source local ores and minerals to use in my pottery, I did a little research on my local area to see what my options are.

I came across a few references to Leith Hill, which is in Surrey at the northern tip of the South Downs. It apparently has an iron rich mineral called 'glauconite' in abundance that's also known as greensands.

My partner Adam and I went walking there last weekend to get some fresh air and investigate further. 

We found quite a lot of red/ orange rock that I collected, thinking it was glauconite', however since then I have been looking it up and I think it's either hematite or magnetite... Either way, it's an iron rich mineral so I'm happy.

I roasted my samples in my kiln at 900'C to clean them up (bio matter burns away) and to perhaps weaken them a bit. 

The ore broke up pretty easily with the pestle and mortar... And then I put the powder in my nutribullet... Which obliterated it to a fine powder! I was very impressed. 

Now I need to research glazes that will let me test my sourced materials so I can begin experimenting...! 

Before roasting - look at the colours..

Before roasting - look at the colours..

After roasting - shells bleached white and the ore is now blood red.

After roasting - shells bleached white and the ore is now blood red.

The top of Leith Hill.

The top of Leith Hill.